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

[tinkering]

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.

[tinkering]

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.

[j cAT]

Originally Posted by tinkering

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.

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.

[777stickman]

Originally Posted by j cAT

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.

[tinkering]

Originally Posted by 777stickman

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

[rhandwor]

Originally Posted by tinkering

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.

[j cAT]

Originally Posted by tinkering

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

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.

[tinkering]

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 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?

- 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.

[j cAT]

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.

[rhandwor]

Originally Posted by tinkering

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 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?

- 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.

[rhandwor]

Originally Posted by tinkering

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 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?

- 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.

[tinkering]

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.

[rhandwor]

Originally Posted by tinkering

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.

[tinkering]

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?

[j cAT]

Originally Posted by tinkering

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.