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My name is Andy White i am only 20 years old Now heres whats going on I have a 1995 Chevy Silverado 1500 5.7 Z71 Truck With around 163,000 miles on it and i have been having problems with my ABS system or so i think it is im not really sure whats going on with this, but heres whats going on. After i (lets say) go to the store park my truck go in the store get what i need and come back i get back in my tuck and back outta my parking spot and then put it in Drive I start going a Bam my rear passenger wheel locks up, but not the rear driver side so i tap on my brakes and it Releases the tire i keep going and it does it again, and again i press the brake just a bit and it again releases this only happens when im driving real slow, or the truck has been sitting for some time (like a Month) now here is what i did to Diagnose on whats going on. My ABS light is on in my truck and this has always been on for as long as i had this truck. i did get the codes for why the light is on just by jumping the two termanls under the dash on the Diagnostic Port. i got a bunch on codes. now i was thinking that mabe my ABS Computer was bad or something im not sure so i just took the 60amp fuse for the ABS Unit out of the control box under the hood thinking that mabe some how the computer was making the ABS to come on when i would be driving slow (kind of like in our 2000 chevy truck the ABS would kick on when coming to a stop and the problem was bad wheel sensors so i just unpluged the driver side to disable the system and it worked) but this just dont make and sence i took a test light to my truck to see if the ABS unit was getting any power and NO its not Because i have that 60amp fuse out. i have NO IDEA whats going on at the moment.all of this started happening when i had to replace the brake-interlock solenoid under the dash on the steering column. but i disabled that too becase you could just pull the shifter outta park anyway, (it’s not adjusted properly but its just a stupid safty feture that i DONT need) all it does is locks the shifter so you HAVE to press the brake to unlock it before you shift outta park thats it. but that still makes no sence why would my rear wheel lock up. ive checked the rear brake shoes and they are Fine i still have 75-50% of them left on both sides. i even adjusted them correctly too. (Not too tight but not too loose either) plus i dont think the E-brake is on the passenger side either. I also know its not the transmission or transfercase either i just had the transfercase out in april of this year, plus if it was the tranny or transfercase it would lock both rear wheels up and make some god awful noise. so would you have any idea whats going on? this is VERY annoying to have happen. Thanks for any help
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First can you post all the codes that you read.
This is the first piece of the puzzle. second
if the problem started after the interlock switch
was replaced. then that maybe the beginning of
the problem.Okay i Got 10 codes that came up i DID put the fuse back in for this too here are the codes in order
About the Brake Inter-lock It doesnt matter if its hooked up or not it does the same thing
Code 68 Locked motor or shorted motor circuit
Code 73 4 Wheel Anti-Lock (4WAL) control unit fault
Code 86 Shorted anti-lock warning lamp
Code 12 System Normal
Code 25 Left front speed sensor fault
Code 21 Right front wheel sensor fault
Code 27 Erratic left front speed sensor
Code 37 Erratic left rear speed signal or erratic VSS signal (1993)
Code 65 4 Wheel Anti-Lock (4WAL) control unit fault
Code 66 4 Wheel Anti-Lock (4WAL) control unit faultQuoted From college man:
First can you post all the codes that you read.
This is the first piece of the puzzle. second
if the problem started after the interlock switch
was replaced. then that maybe the beginning of
the problem.Okay i Got 10 codes that came up i DID put the fuse back in for this too here are the codes in order
About the Brake Inter-lock It doesnt matter if its hooked up or not it does the same thing
Code 68 Locked motor or shorted motor circuit
Code 73 4 Wheel Anti-Lock (4WAL) control unit fault
Code 86 Shorted anti-lock warning lamp
Code 12 System Normal
Code 25 Left front speed sensor fault
Code 21 Right front wheel sensor fault
Code 27 Erratic left front speed sensor
Code 37 Erratic left rear speed signal or erratic VSS signal (1993)
Code 65 4 Wheel Anti-Lock (4WAL) control unit fault
Code 66 4 Wheel Anti-Lock (4WAL) control unit faultYou know if it were me I would clear the codes and check the rear brake adjustment and the operation of the rear shoes, the problem could be mechanical in nature and the ABS codes are just a symptom as ABS’s purpose is to PREVENT wheel lock up not cause it. It may be that the rear shoes are getting hung up on the backing plate, here’s a video that might help better explain what I’m talking about.
Quoted From EricTheCarGuy:
You know if it were me I would clear the codes and check the rear brake adjustment and the operation of the rear shoes, the problem could be mechanical in nature and the ABS codes are just a symptom as ABS’s purpose is to PREVENT wheel lock up not cause it. It may be that the rear shoes are getting hung up on the backing plate, here’s a video that might help better explain what I’m talking about.
I took a look at both Sets of rear brake shoes and i cant find anything wrong with them i mean both sets of shoes have cracks down the middle of the pads. i had someone press the brake peddle to make sure they are Releasing all the way and they are. I cant find anything wrong with the mechanical part of the rear drum brake assembly
If you have cracks on your shoe lining, that indicates a over heating issue of the shoes due to excessive contact between the shoes and the drum service.
Did you lubricate the backing plate where the shoes ride as well as making sure there is no groves that the shoe may be binding up in?
I would also be checking for any restrictions in your brake hose that may stop the return of the brake fluid once the pedal is released.
Did you check your brake pedal free play?
Quoted From dreamer2355:
If you have cracks on your shoe lining, that indicates a over heating issue of the shoes due to excessive contact between the shoes and the drum service.
Did you lubricate the backing plate where the shoes ride as well as making sure there is no groves that the shoe may be binding up in?
I would also be checking for any restrictions in your brake hose that may stop the return of the brake fluid once the pedal is released.
Did you check your brake pedal free play?
In fact this condition is covered in these videos.
I’m suspecting that you have a bad ground to your ABS control unit making it act nutty. Physically check the wiring to this unit and see if it any of it passes by where you did your previous work. You can also check for voltage to your control unit and verify that the ground terminal is in fact grounded or at 0V.
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