ABS Wheel Sensor Replacement 1996 Chevy 3/4 Ton 4X4

1996 Chevy 3/4 Ton K2500 4x4.
The wheel sensor/s need to be replaced. I was glad to hear that he sensors are not sealed in the wheel bearing assemblies on these units. Are there usually ABS sensors on back wheels too? What is the procedure for changing these sensors? Is it worthwhile trying used sensors from Pick a Part or just buy them new from the local auto parts store?

These vehicles are notorious for ABS wheel sensor failure especially in salty areas. The metal under the sensor corrodes and bulges which increases the 'air gap' between the sensor electrode and the reluctor in the hub. A lot of the time, service is restored by removing the sensor, scraping the rusted metal away, and reinstalling the original sensor. There are a number of demonstrations on UTube. Be careful to plug the hole before scraping; to keep crud from interfering with the proper function of the sensor/reluctor inside the hub.

The hub nut measures up at 1 3/8 in. The parts store doesn't have a socket that size. The conversion comes close to 35 mm but a 36 mm socket did the job well; only 32 mm and 36mm are available at my parts store.

Turns out I can access the drivers side ABS wheel speed sensor without removing the rotor; it is located behind/ under the brake caliper. It looks like the passenger side might require the rotor to come off; here's hoping that sensor is OK. The rotor on this heavy duty wheel is held to the hub flange by the press fit of the eight wheel studs. I don't have a decent exploded view diagram here but it looks like maybe those 3 or 4 bolts 'on the backside', have to come out and then the rotor can be separated (if desired) from the rotor/hub unit by pressing the wheel studs out (or maybe by threading a lug nut on the studs a ways and driving them off). It looks like there are a few different 'Series' of configurations. Mine looks like it might be a 'K Series' configuration; 8 bolt, 8600 lb GVW.

According to my parts store, this particular truck (K2500) does not have wheel sensors at the rear wheels, nor could they find a VSS (Vehicle Speed Sensor) listed for the tranny. It seems logical though, that there would be some kind of VSS in the ABS system for the control module or unit to monitor the speed of the rear wheels. The use of a VSS on the tranny has often been discontinued in favor of individual speed sensors located at each wheel.

I will have to buy a new sensor for the driver's side wheel ($70) because it has a longer electrical lead than the passenger side ones I got from the wreckers. The wreckers are worth a try though, if they are easy ones to get off.

I will submit the ABS system results when I get the sensor in, put the fuse back in, and plug the ABS control unit back in. :eek7:

The hub nut measures up at 1 3/8 in. The parts store doesn't have a socket that size. The conversion comes close to 35 mm but a 36 mm socket did the job well; only 32 mm and 36mm are available at my parts store.

Turns out I can access the drivers side ABS wheel speed sensor without removing the rotor; it is located behind/ under the brake caliper. It looks like the passenger side might require the rotor to come off; here's hoping that sensor is OK. The rotor on this heavy duty wheel is held to the hub flange by the press fit of the eight wheel studs. I don't have a decent exploded view diagram here but it looks like maybe those 3 or 4 bolts 'on the backside', have to come out and then the rotor can be separated (if desired) from the bearing/hub unit by pressing the wheel studs out (or maybe by threading a lug nut on the studs a ways and driving them off). It looks like there are a few different 'Series' of configurations. Mine looks like it might be a 'K Series' configuration; 8 bolt, 8600 lb GVW.

This particular truck does not have wheel sensors on the rear wheels nor does it have one on the tranny.

I will have to buy a new sensor for the driver's side wheel ($70) because it has a longer electrical lead than the passenger side ones I got from the wreckers. The wreckers are worth a try though, if they are easy ones to get off.

I will submit the ABS system results when I get the sensor in, put the fuse back in, and plug the ABS control unit back in. :eek7:

I would be very surprised if this gm TRUCK HAS NO TRANSMISSION SENSOR.

the front to rear axles are monitored by the computer. speedo is usually the tranny. abs would compare all sensors other wise how would it work properly with the rear wheels sliding and the front wheels rolling.

I would be very surprised if this gm TRUCK HAS NO TRANSMISSION SENSOR.

the front to rear axles are monitored by the computer. speedo is usually the tranny. abs would compare all sensors other wise how would it work properly with the rear wheels sliding and the front wheels rolling.

Actually, with this K model (4wd) the VSS is located in the T-Case, not the tranny.

Actually, with this K model (4wd) the VSS is located in the T-Case, not the tranny.

Ah ha! I should be more careful wording things. The parts store said there was no rear wheel sensor/s or tranny sensor listed in any of the manufacturers catalogs they have. I did find reference in my Chilton manual to a VSS on the tranny; I didn't see any reference to one on the T-Case but I take your word that this is the case (no pun intended).

j Cat, you make big sense, "...abs would compare all sensors other wise how would it work properly with the rear wheels sliding and the front wheels rolling."
That is very true, "Preventing rear wheel lock up often makes the difference in controlling the vehicle during hard or sudden stops."
There are a number of components that can fail in the ABS system but hopefully this rear VSS is not a dealer item otherwise the wreckers would look appealing again:uhoh:

1996 Chevy 3/4 Ton K2500 4x4.
The wheel sensor/s need to be replaced. I was glad to hear that he sensors are not sealed in the wheel bearing assemblies on these units. Are there usually ABS sensors on back wheels too? What is the procedure for changing these sensors? Is it worthwhile trying used sensors from Pick a Part or just buy them new from the local auto parts store?

These vehicles are notorious for ABS wheel sensor failure especially in salty areas. The metal under the sensor corrodes and bulges which increases the 'air gap' between the sensor electrode and the reluctor in the hub. A lot of the time, service is restored by removing the sensor, scraping the rusted metal away, and reinstalling the original sensor. There are a number of demonstrations on UTube. Be careful to plug the hole before scraping; to keep crud from interfering with the proper function of the sensor/reluctor inside the hub.
I doubt all of your sensors are bad. Use your DVOM set on ohm setting. Rotate each wheel by hand. The meter should go from zero to one as the tire is rotated.
One end of the meter on each terminal. If it doesn't change its bad.

Ah ha! I should be more careful wording things. The parts store said there was no rear wheel sensor/s or tranny sensor listed in any of the manufacturers catalogs they have. I did find reference in my Chilton manual to a VSS on the tranny; I didn't see any reference to one on the T-Case but I take your word that this is the case (no pun intended).

j Cat, you make big sense, "...abs would compare all sensors other wise how would it work properly with the rear wheels sliding and the front wheels rolling."
That is very true, "Preventing rear wheel lock up often makes the difference in controlling the vehicle during hard or sudden stops."
There are a number of components that can fail in the ABS system but hopefully this rear VSS is not a dealer item otherwise the wreckers would look appealing again:uhoh:

I do not have a manual for your vehicle but the sensor for the rear wheels being in the transfer case as was pointed out buy another member has been known to fail or the wiring. so check the wiring and the connector. wires usually have loom protection . when this old it breaks up then the wires chafe on the casing metal .

4wd this would be transfer case 2wd would be transmission.
if the speedometer works properly then this sensor should be good. 1994-96 are not good years with this GM ABS system. many known ABS valve body failures.

also the external sensors get corroded so that the sensor internal coils corrode and open then no signal.

OK. Anti climax.
I put a used sensor in the drivers side where there was no sensor at all. There was a dummy plug in the housing where the sensor goes. It seems like someone maybe changed out the hub and gave up on the whole ABS irritation (I have the rash now:)
It seems like the hub on the drivers side might be different than the passenger side. The hole that accepts the sensor on the drivers side is located aft of the center of the wheel. It looks like the sensor hole on the passenger side is at the top center of the wheel... almost like two different applications?? I am going to call the dealer tomorrow to see if they can tell me some details using their blowup parts diagrams. If I have two different configurations on there, are the reluctors the same inside the hub??
I was very encouraged when I plugged in all of the electrical connectors to the control unit etc.(atop the ABS pump body) and I turned the key on; the ABS light stays on for a couple few seconds; when I start the engine the ABS light comes back on for a couple few seconds. It stays out until I reach 20 or 25 mph, and then voila there it is, ON:eek7: The good news is the front brakes now seem to function properly at low speeds with the light out. Before I did this work they nearly put us through the windshield at slow speeds.
I heard that the system is no longer ABS when the ABS light comes on; the brakes become fully manual. If this is true, why did the ABS system with the light on, try to put us through the windshield at slow speeds?:confused:

- Would resetting the main computer help? I reset the main computer; the ABS light still comes on at 20 to 25 mph.
- The speedometer works fine so the VSS sensor on the transfer case should be OK?
- Should I do the DVOM test (while spinning the wheel) for the front sensors?
- What is the best first step; should I get it scanned when I take it in for the wheel alignment?
Apparently you can read the DTCs without a hand scanner on 1992 - 1995 models using the jumper wire and dash light but 1996 - 1998 trucks require a scan tool but some of the model specific info in the manual seems convoluted. Will it hurt anything if I try the jumper wire code reading procedure, and this turns out to be one of the models that didn't allow that??
Tomorrow I will check the ABS fuse in the dash; I doubt it but worth a look.

What exactly is OBD-I and OBD-II? How do I know which scanner I should buy? The Chilton manual mentions the Tech-I scan tool.

I would guess that the rear sensor is working . the front sensors I would use a volt meter ac volts crank hub by hand at a good rate and you need more than .25 VOLTS AC . a good new sensor will put out .5 volts ac or more.

place a deep socket on the lug stud and use that to crank the hub around .

sounds like they used a different hub assy . look up the correct hub assy part and see whats different. which one is wrong . the front sensor outputs should be close or you will get these issues.

until you fix this remove the big ABS fuse. this will prevent any ABS activation to avoid brake failure.

OK. Anti climax.
I put a used sensor in the drivers side where there was no sensor at all. There was a dummy plug in the housing where the sensor goes. It seems like someone maybe changed out the hub and gave up on the whole ABS irritation (I have the rash now:)
It seems like the hub on the drivers side might be different than the passenger side. The hole that accepts the sensor on the drivers side is located aft of the center of the wheel. It looks like the sensor hole on the passenger side is at the top center of the wheel... almost like two different applications?? I am going to call the dealer tomorrow to see if they can tell me some details using their blowup parts diagrams. If I have two different configurations on there, are the reluctors the same inside the hub??
I was very encouraged when I plugged in all of the electrical connectors to the control unit etc.(atop the ABS pump body) and I turned the key on; the ABS light stays on for a couple few seconds; when I start the engine the ABS light comes back on for a couple few seconds. It stays out until I reach 20 or 25 mph, and then voila there it is, ON:eek7: The good news is the front brakes now seem to function properly at low speeds with the light out. Before I did this work they nearly put us through the windshield at slow speeds.
I heard that the system is no longer ABS when the ABS light comes on; the brakes become fully manual. If this is true, why did the ABS system with the light on, try to put us through the windshield at slow speeds?:confused:

- Would resetting the main computer help? I reset the main computer; the ABS light still comes on at 20 to 25 mph.
- The speedometer works fine so the VSS sensor on the transfer case should be OK?
- Should I do the DVOM test (while spinning the wheel) for the front sensors?
- What is the best first step; should I get it scanned when I take it in for the wheel alignment?
Apparently you can read the DTCs without a hand scanner on 1992 - 1995 models using the jumper wire and dash light but 1996 - 1998 trucks require a scan tool but some of the model specific info in the manual seems convoluted. Will it hurt anything if I try the jumper wire code reading procedure, and this turns out to be one of the models that didn't allow that??
Tomorrow I will check the ABS fuse in the dash; I doubt it but worth a look.

What exactly is OBD-I and OBD-II? How do I know which scanner I should buy? The Chilton manual mentions the Tech-I scan tool.
Sometimes the ring breaks off and may have been removed. It looks like a sprocket on a bike. Anyway the distance from the tooth to your sensor should be close to the same. They should have the same number of teeth. I think the hub assembly has the ring pressed on the new units. You can also get a junk yard part. Look at a new one for your truck at the parts store. Before going to the scrap yard.

OK. Anti climax.
I put a used sensor in the drivers side where there was no sensor at all. There was a dummy plug in the housing where the sensor goes. It seems like someone maybe changed out the hub and gave up on the whole ABS irritation (I have the rash now:)
It seems like the hub on the drivers side might be different than the passenger side. The hole that accepts the sensor on the drivers side is located aft of the center of the wheel. It looks like the sensor hole on the passenger side is at the top center of the wheel... almost like two different applications?? I am going to call the dealer tomorrow to see if they can tell me some details using their blowup parts diagrams. If I have two different configurations on there, are the reluctors the same inside the hub??
I was very encouraged when I plugged in all of the electrical connectors to the control unit etc.(atop the ABS pump body) and I turned the key on; the ABS light stays on for a couple few seconds; when I start the engine the ABS light comes back on for a couple few seconds. It stays out until I reach 20 or 25 mph, and then voila there it is, ON:eek7: The good news is the front brakes now seem to function properly at low speeds with the light out. Before I did this work they nearly put us through the windshield at slow speeds.
I heard that the system is no longer ABS when the ABS light comes on; the brakes become fully manual. If this is true, why did the ABS system with the light on, try to put us through the windshield at slow speeds?:confused:

- Would resetting the main computer help? I reset the main computer; the ABS light still comes on at 20 to 25 mph.
- The speedometer works fine so the VSS sensor on the transfer case should be OK?
- Should I do the DVOM test (while spinning the wheel) for the front sensors?
- What is the best first step; should I get it scanned when I take it in for the wheel alignment?
Apparently you can read the DTCs without a hand scanner on 1992 - 1995 models using the jumper wire and dash light but 1996 - 1998 trucks require a scan tool but some of the model specific info in the manual seems convoluted. Will it hurt anything if I try the jumper wire code reading procedure, and this turns out to be one of the models that didn't allow that??
Tomorrow I will check the ABS fuse in the dash; I doubt it but worth a look.

What exactly is OBD-I and OBD-II? How do I know which scanner I should buy? The Chilton manual mentions the Tech-I scan tool.
For a scan tool look at Innova 3140 http://www.ebay.com. item 400436247897
I have one of these and it is handy as you need more than codes. You have a lot of older vehicles and if you upgrade models you will need both.
I had to upgrade and I purchased a Autel EBS301 It will open and close brake pads.
Auto Zone and Advanced will pull codes free but freeze frame and other items they won't give you. If you do a lot of work the Innova will pay for itself.

Where in the heck is the Data link connector or the ALDL terminal, and what does it look like? If the location is given in the manual, I sure can't find it.

Where in the heck is the Data link connector or the ALDL terminal, and what does it look like? If the location is given in the manual, I sure can't find it.
Use Google
1996 chevy 3/4 ton truck data link connector
Has pictures.

I can't find my multi meter; we just made a major move. I can't do the AC Volts crank test right now. All I can do presently is check the resistance of the sensors. The brand new one is 1100 ohms +/-, one of the old ones is exactly the same resistance. I will check the ones on the truck right now. Should they be the same resistance installed, when affected by the reluctor ring?

I can't find my multi meter; we just made a major move. I can't do the AC Volts crank test right now. All I can do presently is check the resistance of the sensors. The brand new one is 1100 ohms +/-, one of the old ones is exactly the same resistance. I will check the ones on the truck right now. Should they be the same resistance installed, when affected by the reluctor ring?

resistance is not really a good test. the sensor output voltage test is needed.

sensor may read good resistance and I think the 1100 ohms is a good reading as the 1994 sensors read that amount but what is required is the proper voltage output which checks the sensor and what they call the sensor gear ring.

resistance is not really a good test. the sensor output voltage test is needed.

sensor may read good resistance and I think the 1100 ohms is a good reading as the 1994 sensors read that amount but what is required is the proper voltage output which checks the sensor and what they call the sensor gear ring.
Hi j cAT,
Both the installed sensors have the same 1100 ohms as well.
I will do the cranking output voltage test as soon as I can get my hands on a multimeter that does AC volts.

I would guess that the rear sensor is working . the front sensors I would use a volt meter ac volts crank hub by hand at a good rate and you need more than .25 VOLTS AC . a good new sensor will put out .5 volts ac or more.

place a deep socket on the lug stud and use that to crank the hub around .

sounds like they used a different hub assy . look up the correct hub assy part and see whats different. which one is wrong . the front sensor outputs should be close or you will get these issues.

until you fix this remove the big ABS fuse. this will prevent any ABS activation to avoid brake failure.

I will do the cranking AC voltage output as soon as possible. I am interested to see if the 2 outputs are close to each other.

My parts guy said there is only one hub assembly listed for that vehicle from 1996 to 2000. That may be true but maybe the previous owner installed a hub assembly from 1995 or from a 1 ton or something? I am going to order the drivers side hub assembly and see if it matches the one that is raising our eyebrows. If there is a slight difference in the the air gap because of a slightly different reluctor ring gear, or slightly different reach of the center electrode of the required sensor application, it could cause an imbalanced signal to the control unit; bringing the light on? Sound plausible to you?:cool:
It's too late to order the hub assembly; the parts store is closed for New Years Eve. I will see if there is anyone around there tomorrow; maybe I can have it by Thursday AM.

Happy New Year:runaround: Merry Christmas still.
tinkering
I will take the big ABS fuse out for now. Thanks

... 1994-96 are not good years with this GM ABS system. many known ABS valve body failures...

If this suspicious hub assembly isn't the culprit (I am very suspicious of it) then I will have stay encouraged, and be prepared to check out and change out whatever is necessary including connectors, grounds, conductors, the valve body pump control unit :uhoh:(definitely wrecker$ material). Maybe the ring gears just need a good cleaning. Here's hoping:)

...Use your DVOM set on ohm setting. Rotate each wheel by hand. The meter should go from zero to one as the tire is rotated.
One end of the meter on each terminal. If it doesn't change its bad.

Is it OK to run a current through the ohmmeter; we were always told not to?

Is it OK to run a current through the ohmmeter; we were always told not to?
Mine has a fuse that will blow if hooked up wrong. Mine has a dial on the front which when turned to go from volts to amps.
My test was just a basic test to check if its working. The manuals use different tests
sensors pulse as the wheel turns. Like the old points open and close as the cam rotated. These sensors must have a spring and magnet that opens and closes as the wheel turns. I have a good logic probe that you can watch the current pulse as the signal changes. The computer sends a low voltage and the sensors pulse the voltage.

Is it OK to run a current through the ohmmeter; we were always told not to?

the ohm meter is for NO voltage use. only on measuring for resistance with no power applied.

Now on the speed sensors. these operate by a rotating ring with teeth on it . the sensor is a magnet with a coil. when the steel teeth pass the sensor pick up end the magnetic field is disturbed and a voltage is generated.

there is no switching and it is not like a points distributor set up.

the crank sensor works the same principle. as the engine rotates a voltage is created . the PCM count the pulses to determine the RPM . abs sensor the PCM counts the pulses to determine the vehicle speed.

working on much larger transportation vehicles with these sensors exposed to debris they being magnetic pick up iron dust and then the sensor output falls. also the gap can get out of calibration.

Ideas for you to look for.
http://www.popularmechanics.com/cars/how-to/maintenance/2265091

Ideas for you to look for.
http://www.popularmechanics.com/cars/how-to/maintenance/2265091

Thanks for that :)

If this suspicious hub assembly isn't the culprit (I am very suspicious of it) then I will have stay encouraged, and be prepared to check out and change out whatever is necessary including connectors, grounds, conductors, the valve body pump control unit :uhoh:(definitely wrecker$ material). Maybe the ring gears just need a good cleaning. Here's hoping:)

Bleeding the pump body sounds like a nightmare. Has anybody done one of those!? I really don't relish the thoughts of 'THE BLEED'; the popular mechanics link http://www.popularmechanics.com/cars...enance/2265091 mentions the need of a certain scanner that is needed to bleed the valve body! :( Here is a great demonstration http://www.youtube.com/watch?v=jdiOlEKTqrE
This YouTube shows how to pull the electronic box off of the top of the valve body, and change it out safely http://www.youtube.com/watch?v=lUotkKXG9dY
This YouTube shows how to repair the electronic box http://www.youtube.com/watch?v=Jo76ylqgUR8

This YouTube search has most of the info needed I think (except for the invaluable knowledge base of Automotive Forums) bleeding abs pump chevy - YouTube (http://www.youtube.com/results?search_query=bleeding+abs+pump+chevy&sm=12)

I like this neat demonstration of how to free a seized bleeder with a torch and a rag (should you use heat on the brakes?:) http://www.youtube.com/watch?v=KnJ4IQVritU

Is anyone ever going to give me my first 'Thanks' ? :rofl: I guess I need to join in on other folk's threads to get those)

The video of the bleeder removal with a cutting torch is not how to remove a difficult bleeder fitting. also you do not use a box wrench.

If I find that the bleeder is stuck I use a socket with 6 points then try to remove. this lessens the possible breaking of the fitting.if it still does not loosen I get a small tipped propane torch and just heat up the fitting. then when the fitting is looking a little red place the cold socket on the fitting and gradually rotate/increase force to loosen. as the fitting shrinks it will break loose. doing it this way the fluid should not get damaged. also replace these fittings. since the fluid is now heated before pushing the piston back open the bleed screw and push back the piston. you will see debris in the fluid. if the pistons are pushed back with not dumping this piston fluid this is why many ABS valve units fail. this is my procedure when doing the brake jobs . the piston fluid is always dirty and damaged.

The video of the bleeder removal with a cutting torch is not how to remove a difficult bleeder fitting. also you do not use a box wrench.

If I find that the bleeder is stuck I use a socket with 6 points then try to remove. this lessens the possible breaking of the fitting.if it still does not loosen I get a small tipped propane torch and just heat up the fitting. then when the fitting is looking a little red place the cold socket on the fitting and gradually rotate/increase force to loosen. as the fitting shrinks it will break loose. doing it this way the fluid should not get damaged. also replace these fittings. since the fluid is now heated before pushing the piston back open the bleed screw and push back the piston. you will see debris in the fluid. if the pistons are pushed back with not dumping this piston fluid this is why many ABS valve units fail. this is my procedure when doing the brake jobs . the piston fluid is always dirty and damaged.

6 point always. I thought the video shows pretty extreme heating of the fitting and area (and the fluid); I like your prescribed touch. Whats wrong with cooling it with a rag? That is real good thinking j cAT; dump the affected fluid out via the bleeder before squeezing the piston back. How would the damaged/dirty fluid find it's way from the caliper piston back into the ABS valve; would there be enough fluid pushed back from the piston to reach the master cylinder (and work it's way from there to the ABS valve)? Regardless, it is very wise thinking to expel that damaged fluid, and debris from the system.

This is a perfect example of why I say Automotive Forums' knowledge base it invaluable. THANKS

Push the brake pedal slowly and refill the master cylinder after each bleed. I replaced the valve body unit on my sons 1997 two wheel drive. I had to use a scan tool to bleed it properly.
When I lived in Ohio I had to use a torch to free up bleed screws.
His truck had bad wiring as I went to a scrap yard and got used harness and a spindle.
I got rebuilt calipers and a used rotor. The wiring to the speed sensor on the transmission was also bad. The valve body was also from a scrap yard. I had an OTC 4000E and I had to get another module and connector. It was last updated to a 2002 duece and a 1998 module for brakes. At this point they required you to buy a new scanner around $2000 as I was retired I didn't buy a new scanner until I got some cheaper scanners.

6 point always. I thought the video shows pretty extreme heating of the fitting and area (and the fluid); I like your prescribed touch. Whats wrong with cooling it with a rag? That is real good thinking j cAT; dump the affected fluid out via the bleeder before squeezing the piston back. How would the damaged/dirty fluid find it's way from the caliper piston back into the ABS valve; would there be enough fluid pushed back from the piston to reach the master cylinder (and work it's way from there to the ABS valve)? Regardless, it is very wise thinking to expel that damaged fluid, and debris from the system.

This is a perfect example of why I say Automotive Forums' knowledge base it invaluable. THANKS

when you drain the cal pistons with my method into a container using a clear plastic tubing routing higher than screw port then lower into your container. as you push back slowly using a C clamp the debris amount will surprise you. those particles will screw up the ABS valves from seating properly. I have found even in new calipers a lot of dirt / material. then with the piston fully back close the bleed screw . load calipers then do your normal bleed procedure to remove any air ..usually none.

only work one brake unit at a time.

IF (big IF) the vehicle has stock-type rubber brake hoses, it's useful to lightly pinch the hose to absolutely prevent contaminated fluid from being forced backward through the system.

In the early years, I used a needle-nose vice-grip to lightly pinch the hose. Now I use dedicated hose-pinching tools. Either way, the hose doesn't have to be clamped tightly. Just enough to prevent fluid flow.

DO NOT do this on aftermarket steel braid/Teflon liner brake hoses. They are RUINED when pinched.

I will do the cranking AC voltage output as soon as possible. I am interested to see if the 2 outputs are close to each other.
My parts guy said there is only one hub assembly listed for that vehicle from 1996 to 2000. That may be true but maybe the previous owner installed a hub assembly from 1995 or from a 1 ton or something? I am going to order the drivers side hub assembly and see if it matches the one that is raising our eyebrows. If there is a slight difference in the the air gap because of a slightly different reluctor ring gear, or slightly different reach of the center electrode of the required sensor application, it could cause an imbalanced signal to the control unit; bringing the light on? Sound plausible to you?:cool:

I did the cranking AC voltage output test. The passenger side sensor put out 0.4 VAC while cranking the hub with a socket on a lug stud; as fast as I could. Guess what? The drivers side produced zero VAC! That is very encouraging to me.Now I have thicker suspicions that the wrong hub is on the drivers side. Both of the wheel sensors measured 1100 ohms so I was expecting to see some kind of out put there. I am going to order the correct hub and do a visual comparison; I will also check the ring gear for fouling, wear and/or breakage on the next above freezing day we get here.

I did the cranking AC voltage output test. The passenger side sensor put out 0.4 VAC while cranking the hub with a socket on a lug stud; as fast as I could. Guess what? The drivers side produced zero VAC! That is very encouraging to me.Now I have thicker suspicions that the wrong hub is on the drivers side. Both of the wheel sensors measured 1100 ohms so I was expecting to see some kind of out put there. I am going to order the correct hub and do a visual comparison; I will also check the ring gear for fouling, wear and/or breakage on the next above freezing day we get here.

good work you will be an expert with these type failures.

I did the cranking AC voltage output test. The passenger side sensor put out 0.4 VAC while cranking the hub with a socket on a lug stud; as fast as I could. Guess what? The drivers side produced zero VAC! That is very encouraging to me.Now I have thicker suspicions that the wrong hub is on the drivers side. Both of the wheel sensors measured 1100 ohms so I was expecting to see some kind of out put there. I am going to order the correct hub and do a visual comparison; I will also check the ring gear for fouling, wear and/or breakage on the next above freezing day we get here.
The temperatures I observed on the internet for your area you need a wood burner for your garage. The radiant heaters for small propane tanks will take out the chill in a garage.

The temperatures I observed on the internet for your area you need a wood burner for your garage. The radiant heaters for small propane tanks will take out the chill in a garage.

I've got a wood stove and a radiant heater for the bottle but my garage isn't built yet; sooon:rofl:
The weather is going to be above zero for a couple of days; maybe I can get some things done.

good work you will be an expert with these type failures.
Thanks, it feels more hopeful now. I'll let you know when I get the hub changed out. Maybe this thread will be of some use to someone else too.

I did the cranking AC voltage output test. The passenger side sensor put out 0.4 VAC while cranking the hub with a socket on a lug stud; as fast as I could. Guess what? The drivers side produced zero VAC! That is very encouraging to me.Now I have thicker suspicions that the wrong hub is on the drivers side. Both of the wheel sensors measured 1100 ohms so I was expecting to see some kind of out put there. I am going to order the correct hub and do a visual comparison; I will also check the ring gear for fouling, wear and/or breakage on the next above freezing day we get here.

The parts guy says it's the same hub for both sides. That would explain why the driver's sensor would have to be mounted upside down compared to the passenger sensor. I took the driver's hub off. I could now see a second sensor mounting screw hole; there is one on either side of the sensor hole on the hub. The second hole was hiding under a bunch of crud. Now I am able to mount the sensor with the cable pointing inboard. That is good in itself but when I got the hub off and had a better look, I saw that the sensor was not in fact all the way flush with the hub. I was working by feel when the hub was still on; when I thought the screw felt tight, the sensor was actually bound in the hole; it was a good 1/16 inch shy of flush. I got it all cleaned up and properly installed. The prevailing trouble may have been the driver's sensor was not mounted flush which would mean an enormous air gap.

When I redid the driver's side cranking AC voltage output test I achieved 1.2 VAC. That is more than j cAT said to expect. j cAT is that OK? On the previous day I achieved only .4 VAC on the passenger side but that was with the brake caliper drag limiting top RPM. I have that caliper off now, so tomorrow I will redo the passenger side cranking AC voltage output test. I hope to achieve an output similar to the driver's side. How close does it have to be to satisfy computer parameters?

I also looked through the sensor hole to inspect the reluctor gear. There was a ton of blue grease in there. Using a screwdriver, I stuffed a rag down through the hole, to make contact with the reluctor teeth. I turned the hub around by hand, intending to swab out a bunch of that grease; I did that a few times. All of the grease appeared to be very clean (no grit grime or metallic filings). There is a bit of grease still between the teeth; I can't get it perfectly wiped without pulling the hub apart. I think it is good enough.

I will let you know my results tomorrow.

The parts guy says it's the same hub for both sides. That would explain why the driver's sensor would have to be mounted upside down compared to the passenger sensor. I took the driver's hub off. I could now see a second sensor mounting screw hole; there is one on either side of the sensor hole on the hub. The second hole was hiding under a bunch of crud. Now I am able to mount the sensor with the cable pointing inboard. That is good in itself but when I got the hub off and had a better look, I saw that the sensor was not in fact all the way flush with the hub. I was working by feel when the hub was still on; when I thought the screw felt tight, the sensor was actually bound in the hole; it was a good 1/16 inch shy of flush. I got it all cleaned up and properly installed. The prevailing trouble may have been the driver's sensor was not mounted flush which would mean an enormous air gap.

When I redid the driver's side cranking AC voltage output test I achieved 1.2 VAC. That is more than j cAT said to expect. j cAT is that OK? On the previous day I achieved only .4 VAC on the passenger side but that was with the brake caliper drag limiting top RPM. I have that caliper off now, so tomorrow I will redo the passenger side cranking AC voltage output test. I hope to achieve an output similar to the driver's side. How close does it have to be to satisfy computer parameters?

I also looked through the sensor hole to inspect the reluctor gear. There was a ton of blue grease in there. Using a screwdriver, I stuffed a rag down through the hole, to make contact with the reluctor teeth. I turned the hub around by hand, intending to swab out a bunch of that grease; I did that a few times. All of the grease appeared to be very clean (no grit grime or metallic filings). There is a bit of grease still between the teeth; I can't get it perfectly wiped without pulling the hub apart. I think it is good enough.

I will let you know my results tomorrow.

do not worry about the grease if it is clean. it is OK to have grease on the sensor encoder wheel. on the volts ac being more than the .4 volts this can happen if the sensor is too close. the hub manufacturers add a small shim to correct for this. you want the voltage to be about the same , does not have to be exactly the same. 1.2 is a little high if you did crank at the same speed on each side.

do not worry about the grease if it is clean. it is OK to have grease on the sensor encoder wheel. on the volts ac being more than the .4 volts this can happen if the sensor is too close. the hub manufacturers add a small shim to correct for this. you want the voltage to be about the same , does not have to be exactly the same. 1.2 is a little high if you did crank at the same speed on each side.

I cranked both sides as fast as I could (maybe 3 or 4 RPS. Is this too fast?). This AM, the passenger side now produces .6 VAC after taking the caliper (drag) off. That is still .6 VAC difference between the two sides.
Should I try to shim the 1.2 VAC side out a bit to lower the VAC, or take the hub off the .6 side and see if I can clean it up to get the voltage up closer to the 1.2 VAC side? I am going to take the .6 VAC hub off and clean up the sensor mounting surface to see if the I can get the VAC to go up.
If I go the shim route, where do you get shims? I didn't see any at the wreckers; I was watching for them. Can I make one out of shim stock, or a tin can or something; how thick should I go?

Here is another question idea? Would it work for me to file a wee bit off of the end of the sensor, to increase the air gap; maybe .010" - .020"? I have an old sensor I could experiment with, or better yet maybe I should just get busy and make a couple of shims?

I cranked both sides as fast as I could (maybe 3 or 4 RPS. Is this too fast?). This AM, the passenger side now produces .6 VAC after taking the caliper (drag) off. That is still .6 VAC difference between the two sides.
Should I try to shim the 1.2 VAC side out a bit to lower the VAC, or take the hub off the .6 side and see if I can clean it up to get the voltage up closer to the 1.2 VAC side? I am going to take the .6 VAC hub off and clean up the sensor mounting surface to see if the I can get the VAC to go up.
If I go the shim route, where do you get shims? I didn't see any at the wreckers; I was watching for them. Can I make one out of shim stock, or a tin can or something; how thick should I go?

Here is another question idea? Would it work for me to file a wee bit off of the end of the sensor, to increase the air gap; maybe .010" - .020"? I have an old sensor I could experiment with, or better yet maybe I should just get busy and make a couple of shims?

starter shim kit has the various thickness you need. just stick an edge in under the sensor with it locked in place and see what you get . these are stamped or use you shim tool to determine what size shim needed.

I cranked both sides as fast as I could (maybe 3 or 4 RPS. Is this too fast?). This AM, the passenger side now produces .6 VAC after taking the caliper (drag) off. That is still .6 VAC difference between the two sides.
Should I try to shim the 1.2 VAC side out a bit to lower the VAC, or take the hub off the .6 side and see if I can clean it up to get the voltage up closer to the 1.2 VAC side? I am going to take the .6 VAC hub off and clean up the sensor mounting surface to see if the I can get the VAC to go up...

OK, I elected to pull the sensor out of the passenger side hub (the one that was delivering .6 VAC) to see if I could get the output to increase by cleaning up rust and corrosion that might be present at the mounting surface; it paid off. Although the sensor coil WOULD NOT come out of the hole, despite all of my patient coaxing, the plastic coil sheath stayed in the hole (I managed to retrieve it using a hooked tool; keeping the hub inverted so nothing would fall inside). I elected to replace both sides with brand new sensor units (I do not want to have to take the thing apart again, so I sprung for the $125.00). I applied white lithium wheel bearing grease to the new sensors before installing them in the holes.

Someone described turning the hub at approximately 1 RPS for the 'AC voltage cranking output test'; so for this last test I used 1 RPS; both side's outputs were balanced at around 0.5 VAC. If I crank like a madman I am able to reach about 1.2 VAC. I think the 0.5 VAC at 1 RPS looks right to me.

I also elected at this time to change the routing of the sensor cables. The manufacturer ran it between the backing plate and the steering knuckle, where there is not enough room for the sensor coil to pass through; this made it necessary to remove the hub to change the sensor. I ran the cable along the inboard side of the steering knuckle, and then up to the 'cable guide bracket' fastened to one of the upper ball joint mounting bolts. I made sure I gave the cable the slack required when the wheel is turned to the limit. In my opinion, this is a nice improvement.

After all these ABS repairs and test results on the front wheels, I will be surprised if I have to move on to the ABS computer or the ABS valve body.
I should be finished the rest of the repairs on the truck tomorrow, so I will post the ABS road test results then :cool:

That's it! The road test proved a success. The ABS trouble is gone, and a few improvements have been made too. I am happy too, that I don't have to go into the computer or the valve body.

Thank you j cAT and everybody for your fantastic help!!:runaround:

That's it! The road test proved a success. The ABS trouble is gone, and a few improvements have been made too. I am happy too, that I don't have to go into the computer or the valve body.

Thank you j cAT and everybody for your fantastic help!!:runaround:

it did take some time but the cost was very much cheaper than a repair shop. I do not have the knowledge of your emergency brake cables. I did not have help on that issue you had.

with the info on your abs repair I believe that this will be working properly for a good amount of time. good luck..

it did take some time but the cost was very much cheaper than a repair shop. I do not have the knowledge of your emergency brake cables. I did not have help on that issue you had.

with the info on your abs repair I believe that this will be working properly for a good amount of time. good luck..
Thanks a bunch again j cAT. It is such a joy not to see the ABS light. The repair shop bill for the ABS, and the other repairs I did would have flattened my wallet.

We did a bunch of pictures of the E brake issues. You might find it a bit interesting; I am going to post them and the results at http://www.automotiveforums.com/vbulletin/showthread.php?p=7107491&posted=1
So far, I got the E Brake working but the pedal could be higher. That is all I am going to do to it for now; it is 30 below today.