ABS Light Always ON 1996 Chevrolet Cheyenne 4x4

[tinkering]

The ABS light is ALWAYS ON. The front brakes grab really bad when the truck has been sitting for a few days, or when it is rainy driving conditions. Where do I start?

[gremlin96]

you need to go to a auto parts store and see if they have a scanner that can read the abs. get the codes then start trouble shooting from there. you can clean up the sensors and see if that fixes it. but you will need to reset the codes. check for broken wires and crud in the connectors.

[tinkering]

Originally Posted by gremlin96

you need to go to a auto parts store and see if they have a scanner that can read the abs. get the codes then start trouble shooting from there. you can clean up the sensors and see if that fixes it. but you will need to reset the codes. check for broken wires and crud in the connectors.

Where are the sensors, and how do you clean them? Do you need the scanner to reset the codes? Broken wires and crud in the connectors at the wheels?

[autojoe]

most auto parts stores cant read these codes with their generic scan tools.these codes are stored in the body control module.check your wheel speed sensors that are attached to each wheel on the inside.check electrical connectors and wiring to connectors.make sure no broken teeth on hub and no builup of dirt.lots of people dont have money to fix or dont like abs so they disconnect fuse or abs module connector.I would check above items and if that is ok you would have to take to a shop one that specializes in electrical diagnostics and they would read codes and also on their scan tool check the wheel sensors if operating.you need enhanced scan tool for working on abs and bi-directional controls.you are very limited on what you can do or check without proper testing equipment.

[autojoe]

also the sensors have 2 wires going to them.the only wires at wheels.

[j cAT]

Originally Posted by tinkering

Where are the sensors, and how do you clean them? Do you need the scanner to reset the codes? Broken wires and crud in the connectors at the wheels?

the sensors need be checked with an ohm meter. I forget what amount but 1000-2000 ohms or so. If open this is what I had with the 94 s10 pu. this is expensive stuff. I just put the black tape over the dash amber light.

brakes you should remove the rear drums and see if the shoes are worn/wearing only at the top if so the drums are too worn. also with a big ridge on the drum edge this is indicating its worn.

GM had many problems when they started out trying to get ABS working correctly in vehicles. I have had many years experience with the ABS back in the 1970's with larger vehicles that had abs systems[not GM]. GM did a very poor cheapo job with this 90's abs experiment.

[autojoe]

resistance doesn't always work.best way to test is with a dso.

[j cAT]

Originally Posted by autojoe

resistance doesn't always work.best way to test is with a dso.

well on the 1994 S10 the manual stated the resistance check. with the pickup coil open no need to go further . what I also found was the plastic enclosure had a small crack, this is why the coil corroded open . with the coil open no way any output is possible.

[autojoe]

what manual?haynes?dynamic testing is always better.resistance can vary with temperature.best way is to retrieve abs codes from the body control module and use an enhanced scan tool to pinpoint problem area.

[j cAT]

Originally Posted by autojoe

what manual?haynes?dynamic testing is always better.resistance can vary with temperature.best way is to retrieve abs codes from the body control module and use an enhanced scan tool to pinpoint problem area.

when the abs sensor is open / no resistance as in a open circuit this device can not work no how no way. straping on a scanner /scope /voltmeter etc is not going to get any output.

with code retrival this helps narrow down where the problem is . DIY backyard mechanics most times lack this abs expensive test equipment. especially the ABS capabile scanner which requires GM diagnostic abilities. this why testing with an ohmmeter/voltmeter and disassembly of these very failure prone sensors usually works out, with the issues he has posted here.

taking a 1996 vehicle to the dealership with this repair could cost more to repair than the actual vehicle value.

finding a repair shop with the ability to read the ABS code could be a problem .

110% of these vehicles of this vintage have these issues if still on the road today.

[autojoe]

that is why most of the time backyard mechanics cant fix their vehicles beacause you cant guess and proper test equipment is required to diagnose.you are right you can check minor things but most of the time it is something more.sometimes you have to bite the bullet and take to someone that has the knowledge and proper testing equipment.the days of shoemakering and backyard mechanics fixing their own vehicles are becoming obsolete.I used to be one long time ago and no own thousands of dollars in testing equipment which have to upgrade annually and also go to training classes on a regular basis to keep abreast of changes in field.

[j cAT]

Originally Posted by autojoe

that is why most of the time backyard mechanics cant fix their vehicles beacause you cant guess and proper test equipment is required to diagnose.you are right you can check minor things but most of the time it is something more.sometimes you have to bite the bullet and take to someone that has the knowledge and proper testing equipment.the days of shoemakering and backyard mechanics fixing their own vehicles are becoming obsolete.I used to be one long time ago and no own thousands of dollars in testing equipment which have to upgrade annually and also go to training classes on a regular basis to keep abreast of changes in field.

these forums and many others out there provide much of the secret info that GM and the other vehicle manufactures deny to persons/small repair shops, looking to repair these vehicles.

It helps to have a good knowledge of electronics and electrical systems.
with no training in this area your at a great disadvantage. understanding the repair manual and acting on the tests to determine component defect/condition.

one thing I learned many years ago ....the computer/scanner /diagnosing machines can't fix the problem ! just gets you going in the correct direction ..

knowing what to look for is what these forums provide , rather than changing parts to determine defective component.

even dealerships do this ! perhaps its just to jackup the repair bill so manager gets bigger $$$$... or techs lack the basic electrical/electronic knowledge .

with these vehicles this issue has much internet info for DIY repair..

[jdmccright]

I have also seen where either the wheel bearings or the brakes are heated up enough to soften the plastic that the ABS sensors are embedded in. This can make them become misaligned or move to make contact with the reluctor ring and damage it. I don't know which is the cause, I've only seen the aftermath from a purchased vehicle.

[777stickman]

Lots of good info & speculation in this tread. But until this guy takes the initiative to spend $40-50 for a shop to access the ABS system for codes and then post the code numbers here, it still remains speculation.

[tinkering]

Originally Posted by autojoe

most auto parts stores cant read these codes with their generic scan tools.these codes are stored in the body control module.check your wheel speed sensors that are attached to each wheel on the inside.check electrical connectors and wiring to connectors.make sure no broken teeth on hub and no builup of dirt.lots of people dont have money to fix or dont like abs so they disconnect fuse or abs module connector.I would check above items and if that is ok you would have to take to a shop one that specializes in electrical diagnostics and they would read codes and also on their scan tool check the wheel sensors if operating.you need enhanced scan tool for working on abs and bi-directional controls.you are very limited on what you can do or check without proper testing equipment.

I don't see any wires or sensors in there. Do you have to take the rotor off pr something, to see it sensor? If I just undo all the connectors on the ABS control body, will the brakes work the old way? I know there are ways to spend money to get the ABS working but if they will work without ABS, that is fine with me. Brakes always worked fine for me before ABS came along...