Help! 951 ABS Fault
11-22-2004, 08:07 PM
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Help! 951 ABS Fault
Hi,
The ABS on my recently purchased 1990 951 doesn't work, I have searched the archives but not found anyone with quite the same problem as this:
With the ignition on the antilock lamp lights up and goes off as soon as the engine fires up - proving at least that the light is connected!
When I hit the brakes hard on a wet road I get locked wheels with no ABS action at all. The warning lamp does NOT illuminate before or during or after braking nor at any other time whilst driving.
I have a factory manual which so I know where all the ABS components are located. As a test I pulled the ABS relay from the main fuse box and this causes the warning lamp to light up as you might expect.
My next Idea is to check the two relays on the pump hidden under the front wing(fender)
Incidentally I do have 17" wheels but I understand if this was the problem I should get a warning lamp?
What should I do next???
Thanks,
KC
The ABS on my recently purchased 1990 951 doesn't work, I have searched the archives but not found anyone with quite the same problem as this:
With the ignition on the antilock lamp lights up and goes off as soon as the engine fires up - proving at least that the light is connected!
When I hit the brakes hard on a wet road I get locked wheels with no ABS action at all. The warning lamp does NOT illuminate before or during or after braking nor at any other time whilst driving.
I have a factory manual which so I know where all the ABS components are located. As a test I pulled the ABS relay from the main fuse box and this causes the warning lamp to light up as you might expect.
My next Idea is to check the two relays on the pump hidden under the front wing(fender)
Incidentally I do have 17" wheels but I understand if this was the problem I should get a warning lamp?
What should I do next???
Thanks,
KC
11-30-2004, 06:03 PM
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How hard are you hitting the brakes? I've thought my ABS was inoperative before and it turned out that I wasn't pushing down on the pedal hard enough.
Other possibilities are a loose connector, but then again your ABS warning light turns on and off at startup, right? To access the connectors, you need to raise each corner of the car and remove the respective wheel. It's possible that they may just be dirty or loose.
Definitely a good idea to test the relay and it appears you've already checked the fuse. Worst case scenarios are a bad ABS sensor inside the hub, or the Siemens ABS pump itself, which I seriously doubt is at fault.
Good luck, and let us know how it goes.
Other possibilities are a loose connector, but then again your ABS warning light turns on and off at startup, right? To access the connectors, you need to raise each corner of the car and remove the respective wheel. It's possible that they may just be dirty or loose.
Definitely a good idea to test the relay and it appears you've already checked the fuse. Worst case scenarios are a bad ABS sensor inside the hub, or the Siemens ABS pump itself, which I seriously doubt is at fault.
Good luck, and let us know how it goes.
12-04-2004, 06:09 PM
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Thanks for that Luis.
I have done some further investigation.
Today I pulled the fuse box relay and the two relays fitted to the ABS pump unit which is a Bosch unit incidentally.
I Tested all three relays by operating them with a 12V power supply and checking the contacts actually switched using a continuity tester.
All three relays work fine.
I refitted them to the car and went for a test drive hoping it was maybe a bad connection and that removing and refitting the relays might have cured it but no. Sharp application of the brakes results in the front wheels locking up until you take your foot off the brakes. As I said previously there is no ABS judder on brake pedal and no ABS warning lamp at any point.
To verify the operation of the lamp I disconnected a wheel sensor and went for a drive, the ABS warning lamp lit up and stayed lit almost instantly, so the lamp works OK.
Well I have checked just about all I can, I think the next stage is probably an expensive trip to the auto electricians!
Thanks KC.
I have done some further investigation.
Today I pulled the fuse box relay and the two relays fitted to the ABS pump unit which is a Bosch unit incidentally.
I Tested all three relays by operating them with a 12V power supply and checking the contacts actually switched using a continuity tester.
All three relays work fine.
I refitted them to the car and went for a test drive hoping it was maybe a bad connection and that removing and refitting the relays might have cured it but no. Sharp application of the brakes results in the front wheels locking up until you take your foot off the brakes. As I said previously there is no ABS judder on brake pedal and no ABS warning lamp at any point.
To verify the operation of the lamp I disconnected a wheel sensor and went for a drive, the ABS warning lamp lit up and stayed lit almost instantly, so the lamp works OK.
Well I have checked just about all I can, I think the next stage is probably an expensive trip to the auto electricians!
Thanks KC.
10-30-2011, 10:18 AM
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Hi; I have a 89 951 with exactly the same problem; I have done all the same tests as you and come up with the same results. I am wondering about the control module? I will update as well thanks Steve Turbofxnitro
07-16-2012, 08:22 AM
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Any news on this?
I have the same problem on my 944 Turbo S - 88
Ignition on - ABS light on and stays on (lamp test?) until I ->
Start motor - ABS light off imediatelly (after 10ths of seconds)
Start driving - ABS light off
Brake hard (wheels lock up) - ABS light off
It took me some time to find this post so it seems like a very odd problem (sensors or relay usually seems to be the culprit, but obviously it is not in this case)
I really hope someone has found the culprit.
The only good thin is that the isse can not be seen when doing the MOT
I have the same problem on my 944 Turbo S - 88
Ignition on - ABS light on and stays on (lamp test?) until I ->
Start motor - ABS light off imediatelly (after 10ths of seconds)
Start driving - ABS light off
Brake hard (wheels lock up) - ABS light off
It took me some time to find this post so it seems like a very odd problem (sensors or relay usually seems to be the culprit, but obviously it is not in this case)
I really hope someone has found the culprit.
The only good thin is that the isse can not be seen when doing the MOT
