Need Some ABS Help
Thread Starter
Racer
Joined: Feb 2005
Posts: 338
Likes: 49
From: Quincy,Illinois
Need Some ABS Help
Having an issue with the ABS on my 86. While autocrossing last week, the abs randomly failed to work a few times resulting in wheel lock up. When I would shut the car off, restart, and move at 4mph, the pump would go thru it's self test cycle. Would work fine for a little while, then get random wheel lock up. Sometimes when I just come to a stop, the pump will cycle while sitting still. The ABS light isn't on.
I have a Kent Moore ABS tester and ran it thru all of the tests with no faults found. I tried a different ABS control module and it still does it. I cleaned the rear wheel sensors as they had some brake dust debris stuck to them. When I have had issues in the past, the abs either works or it stops completely. Never had a random issue. I would think that a solenoid would either work all the time or not at all.
Any ideas?
I have a Kent Moore ABS tester and ran it thru all of the tests with no faults found. I tried a different ABS control module and it still does it. I cleaned the rear wheel sensors as they had some brake dust debris stuck to them. When I have had issues in the past, the abs either works or it stops completely. Never had a random issue. I would think that a solenoid would either work all the time or not at all.
Any ideas?
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
I would flush brake fluid and since you are autocrossing use synthetic DOT4. There's not a lot you can do short of swapping parts if a code won't set. Is it the same wheel or random. You might change out brake hoses if they are older also.
Thread Starter
Racer
Joined: Feb 2005
Posts: 338
Likes: 49
From: Quincy,Illinois
Haven't had the system open this year to let any air in.
The hoses are braided SS . The wheels that lock are random.
I Have always read that synthetic brake fluid won't work well in an older abs system.
The hoses are braided SS . The wheels that lock are random.
I Have always read that synthetic brake fluid won't work well in an older abs system.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
Make sure your brake fluid level is topped off. The later systems will do this as well if they even get below the maximum mark.
Also you could be getting false abs activation an erroneous wheel speed sensor. No sure if the tester will read those or not. The early ABS systems are a PITA to work on, IMHO.
Also you could be getting false abs activation an erroneous wheel speed sensor. No sure if the tester will read those or not. The early ABS systems are a PITA to work on, IMHO.
Racer
Joined: Sep 2008
Posts: 403
Likes: 7
From: Space Coast Florida
How are the other parts of the electrical abs system? How old are your relays (should be 2 located near the pump), random pulses could also mean an issue with abs control module, unless you're smashing the brake when you brake each time, shouldn't pulsate randomly.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
I wonder if you're losing power to the ABS system intermittently -causing it to fail in operation, and the re-cycle of the pump at a stop (?)
If it were my car? I'd go find a slippery surface and spend some time deliberately skidding the car to understand the symptoms/behavior/conditions better. In the auto x, you're totally focused on driving/speed/line. The wheel lock up is a distraction and you're not focused on it, or on being a diagnostician at that point. So I'd go try to learn more about the behavior in an time/place where you can focus mainly on that, while also reducing beatage on your tires.
.
If it were my car? I'd go find a slippery surface and spend some time deliberately skidding the car to understand the symptoms/behavior/conditions better. In the auto x, you're totally focused on driving/speed/line. The wheel lock up is a distraction and you're not focused on it, or on being a diagnostician at that point. So I'd go try to learn more about the behavior in an time/place where you can focus mainly on that, while also reducing beatage on your tires.
.
Last edited by Tom400CFI; Oct 24, 2016 at 10:13 AM.
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Racer
Joined: Jul 2015
Posts: 313
Likes: 15
From: Modesto Ca
I removed a complete system out of a 87 and tied the brake lines together.I have the parts removed and would like to find a way to get them to a member that wants them.I locked up the brakes on my car and the abs system never attempted to work.A suggestion-try working on wet pavement?Pm if interested.There are a bunch of fuseable links under the battery.I found some that had been attacked by battery acid/corrosion on my car.1 of the fuseable links/wire runs thru the left rocker panel and powers the abs system.
Last edited by odxr; Oct 24, 2016 at 03:23 PM.