Most common ABS problems.
Thread Starter
Race Director
Joined: Dec 2003
Posts: 14,055
Likes: 909
From: Fremont Ca
2022 C4 of the Year Finalist - Modified
Most common ABS problems.
The ABS is dead in my 91 and NOBODY has a clue as to what it might be.With as my of these cars there are out there I know Im not the only one that has had the ABS die.The system is the same from 86-91 I believe.I want to hear about all the problems people have had.I can fix it if I find the problem.Im not going to go through all the stuff Ive done but I will say it wont pull any TCs and wont communicate with any scanner Ive used,all I get is SERVICE ABS on the panel.Let hear what ya got.
Racer
Joined: Feb 2009
Posts: 486
Likes: 3
From: el cajon ca
The ABS is dead in my 91 and NOBODY has a clue as to what it might be.With as my of these cars there are out there I know Im not the only one that has had the ABS die.The system is the same from 86-91 I believe.I want to hear about all the problems people have had.I can fix it if I find the problem.Im not going to go through all the stuff Ive done but I will say it wont pull any TCs and wont communicate with any scanner Ive used,all I get is SERVICE ABS on the panel.Let hear what ya got.
Thread Starter
Race Director
Joined: Dec 2003
Posts: 14,055
Likes: 909
From: Fremont Ca
2022 C4 of the Year Finalist - Modified
How do you reset it,disconnect the battery?At first it would act up,fine one day next day dead then finally,poof its dead.Ive tried everything,different controllers,different relays,different accelerometers.
Safety Car
Joined: Jan 2004
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Race Director
Joined: Jun 2004
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From: WI
Have you followed the FSM troubleshooting charts? There are things like tipping the accelerometer on it's side to make sure it works, etc etc. I removed the ABS system from my track car, the parts aren't terribly expensive.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Good dealers have a tester for determining what needs repairing on ABS units. A time ago my 87 had a bad rear star wheel pickup (mechanic mangled it pretty good). Recently my 87's ABS started coming on just starting from a stop and coming to a stop. The tester said it was the lateral acceleration switch which I verified with an ohmeter check with it level (its supposed to be zero ohms). I recommend you find a repair place with your year ABS tester.
Thread Starter
Race Director
Joined: Dec 2003
Posts: 14,055
Likes: 909
From: Fremont Ca
2022 C4 of the Year Finalist - Modified
Good dealers have a tester for determining what needs repairing on ABS units. A time ago my 87 had a bad rear star wheel pickup (mechanic mangled it pretty good). Recently my 87's ABS started coming on just starting from a stop and coming to a stop. The tester said it was the lateral acceleration switch which I verified with an ohmeter check with it level (its supposed to be zero ohms). I recommend you find a repair place with your year ABS tester.
Safety Car
Joined: Jun 2006
Posts: 3,629
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From: FL
From my 93 FSM, I can't swear it is the same for a 91.
The CCM on board diagnostics can be used to clear ABS/ASR system DTC's. Follow the procedure below.
1. Ignition OFF
2. Connect jumper from DLC terminal A to terminal G.
3. Ignition ON
4. Press Trip Reset button on DIC repeatedly to display 9.0 in trip monitor area of the instrument cluster.
5. Press Trip ODO twice to change the display to 9.7
6. Hold ENG/MET until "---" appears in the the speedometer area of the cluster.
7. Ignition OFF
8. Remove jumper from DLC
Here is a link to some good ABS information, courtesy of Hib Halverson
http://www.corvetteactioncenter.com/...abs/index.html
The CCM on board diagnostics can be used to clear ABS/ASR system DTC's. Follow the procedure below.
1. Ignition OFF
2. Connect jumper from DLC terminal A to terminal G.
3. Ignition ON
4. Press Trip Reset button on DIC repeatedly to display 9.0 in trip monitor area of the instrument cluster.
5. Press Trip ODO twice to change the display to 9.7
6. Hold ENG/MET until "---" appears in the the speedometer area of the cluster.
7. Ignition OFF
8. Remove jumper from DLC
Here is a link to some good ABS information, courtesy of Hib Halverson
http://www.corvetteactioncenter.com/...abs/index.html
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
But you could just pay for the diagnosis and do your own repair. Without the diagnosis you have no means to find the fault. The first time my ABS malfunctioned I put the car on jackstands and used my oscilloscope to look at the waveform of each wheel sensor while I spun them and could'nt see any difference on any wheel, but later a tester found a defective wheel sensor.
Team Owner
Joined: Dec 1999
Posts: 34,873
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
From my 93 FSM, I can't swear it is the same for a 91.
The CCM on board diagnostics can be used to clear ABS/ASR system DTC's. Follow the procedure below.
1. Ignition OFF
2. Connect jumper from DLC terminal A to terminal G.
3. Ignition ON
4. Press Trip Reset button on DIC repeatedly to display 9.0 in trip monitor area of the instrument cluster.
5. Press Trip ODO twice to change the display to 9.7
6. Hold ENG/MET until "---" appears in the the speedometer area of the cluster.
7. Ignition OFF
8. Remove jumper from DLC
Here is a link to some good ABS information, courtesy of Hib Halverson
http://www.corvetteactioncenter.com/...abs/index.html
The CCM on board diagnostics can be used to clear ABS/ASR system DTC's. Follow the procedure below.
1. Ignition OFF
2. Connect jumper from DLC terminal A to terminal G.
3. Ignition ON
4. Press Trip Reset button on DIC repeatedly to display 9.0 in trip monitor area of the instrument cluster.
5. Press Trip ODO twice to change the display to 9.7
6. Hold ENG/MET until "---" appears in the the speedometer area of the cluster.
7. Ignition OFF
8. Remove jumper from DLC
Here is a link to some good ABS information, courtesy of Hib Halverson
http://www.corvetteactioncenter.com/...abs/index.html
I know that my 87 ABS system can't be diagnosed with a scan tool. That system does not communicate with the ECM so a specific ABS tester must be used.
Have you tried cleaning the wheel speed sensors? Are the connectors tight and have no corrosion or dirt that could result in a bad contact? Are the sensors at the correct wheel? They are left and right specific.
Try pulling both front hubs to see if the reluctor rings are where they belong or have no broken teeth.
It's also possible that the ABS controller is having intermittent issues. Are the wire harness connectors at the controller tight? The ABS unit has three relays, a pump motor relay, a solenoid relay, and a module relay; maybe one is going south. Also check the ground connectors to make sure nothing is loose or corroded.
Thread Starter
Race Director
Joined: Dec 2003
Posts: 14,055
Likes: 909
From: Fremont Ca
2022 C4 of the Year Finalist - Modified
Don't think the early ABS cars had the same diagnostic procedures. A GM Tech I with the brake module can be used to display ABS related codes but the paper clip method works too but only for the 92 and later cars.
I know that my 87 ABS system can't be diagnosed with a scan tool. That system does not communicate with the ECM so a specific ABS tester must be used.
Have you tried cleaning the wheel speed sensors? Are the connectors tight and have no corrosion or dirt that could result in a bad contact? Are the sensors at the correct wheel? They are left and right specific.
Try pulling both front hubs to see if the reluctor rings are where they belong or have no broken teeth.
It's also possible that the ABS controller is having intermittent issues. Are the wire harness connectors at the controller tight? The ABS unit has three relays, a pump motor relay, a solenoid relay, and a module relay; maybe one is going south. Also check the ground connectors to make sure nothing is loose or corroded.
I know that my 87 ABS system can't be diagnosed with a scan tool. That system does not communicate with the ECM so a specific ABS tester must be used.
Have you tried cleaning the wheel speed sensors? Are the connectors tight and have no corrosion or dirt that could result in a bad contact? Are the sensors at the correct wheel? They are left and right specific.
Try pulling both front hubs to see if the reluctor rings are where they belong or have no broken teeth.
It's also possible that the ABS controller is having intermittent issues. Are the wire harness connectors at the controller tight? The ABS unit has three relays, a pump motor relay, a solenoid relay, and a module relay; maybe one is going south. Also check the ground connectors to make sure nothing is loose or corroded.
Thread Starter
Race Director
Joined: Dec 2003
Posts: 14,055
Likes: 909
From: Fremont Ca
2022 C4 of the Year Finalist - Modified
But you could just pay for the diagnosis and do your own repair. Without the diagnosis you have no means to find the fault. The first time my ABS malfunctioned I put the car on jackstands and used my oscilloscope to look at the waveform of each wheel sensor while I spun them and could'nt see any difference on any wheel, but later a tester found a defective wheel sensor.
Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Find a shop that will let you watch what they do or buy your own Tech 1 for about 1800 if you can find one. I have never heard my ABS self test the light blinks and that is it and it has never gone off no matter how hard I try. If the ABS needs bleeding it is going to be messy and hard to avoid send a letter to GM about the poor design like they actually care.