Any 964 ABS/AWD Experts Here?

[1990C4S]

I have an ongoing 'fault' that occurs after a couple of minutes of driving, red brake light, red AWD light, and the dreaded bell.

I have some aftermarket software (Bergvill) that properly diagnosed my failed wheel speed sensor, and a faulty accelerometer, but I still have a persistent fault after several minutes of driving.

My Bergvill software does not seem to communicate with the ECU when the car is running, and when the car is OFF there is no fault stores.

The ABS pump seems to work properly when the key is ON, but after sitting it does seem to take a long time to shut off.

I have bled the brakes and added fresh fluid, I have not bled the AWD. It seems a bit tedious without a Hammer, but I think I should do it soon.

Anyone know enough about the 'ABS/AWD monitor procedure' to point me in the right direction? (I tried the 964/993 forum with zero success/suggestions.)

[Planter91C2]

If your speedometer is working, I would remove each wheel and clean the abs sensors from brake dust accumulation. There is 1 bolt on the top of each sensor, remove and clean. It could be your problem

[group911@aol.co]

Anybody near you that you could swap computers with? Your computer should be an "00" used until mid 91

[1990C4S]

Originally Posted by Planter91C2

If your speedometer is working, I would remove each wheel and clean the abs sensors from brake dust accumulation. There is 1 bolt on the top of each sensor, remove and clean. It could be your problem

Although my software tells me everything is good, I think this is a good starting point. I was also thinking of checking the sensor signal at the ECU end with a scope.

Originally Posted by group911@aol.co

Anybody near you that you could swap computers with? Your computer should be an "00" used until mid 91

Seems unlikely that this is the problem, I didn't have any trouble when I daily drove it years ago, but I will check.

[Planter91C2]

Any update? Now I’m having the same problem 1991 c2

[1990C4S]

Originally Posted by Planter91C2

Any update? Now I’m having the same problem 1991 c2

No, this is my 'spare' car, and I'm kind of busy right now getting my yard ready for a wedding. I might dig into it Monday.

[1990C4S]

I am going to start here, checking resistance of each wheel speed sensor at the ABS controller connector.

They should be about 1,000 Ohms.

[Planter91C2]

I removed all my wheel sensors and cleaned them, they are like brand new 50k original miles. Let me know what you find out.
Thanks

[unclebilly]

I had this exact situation. I took it to an Indy shop and the problem was… very slightly low brake fluid. It makes sense, every time I went over a bump, the lights would come on.

Top up your brake fluid and report back.

[1990C4S]

Originally Posted by unclebilly

I had this exact situation. I took it to an Indy shop and the problem was… very slightly low brake fluid. It makes sense, every time I went over a bump, the lights would come on.

Top up your brake fluid and report back.

Thank you for the suggestion.

Never hurts to try, but I'm pretty sure I bypassed that sensor last year as one of my tests. But I'm willing to try anything that's easy...

[1990C4S]

Jumpering the brake fluid level sensor did not change the result for me, unfortuately.

I found three ABS sensors that read between 1,050 Ohms and 1,080 Ohms, but the front right was 1,700 Ohms.

I am looking online for a new sensor now, although my software does not tell me this is the problem, it certainly appears to be out of spec.

While I wait for it to ship I can drill out the bolt that held it in....