Airflite40

I guess the car doesn't want to be sold since the day I officially put it for sale it starts acting up

I have an ABS issue.

When you start the car after 15-20 seconds the light comes on. If you start the car and drive off and drive normally the light DOES NOT come on, but will turn on once the car stops moving.

From what I know about ABS this rules out the sensors right?

the brakes work perfectly fine stop great

Airflite40

any ideas? i'm gonna try to pull the fender liner and check the ground to the ABS unit tomorrow, maybe some water got in there.

SirLapsalot

I'm new to 944 ownership but from your description it does sound like you have a problem with the controller or ground as you thought. But just to be sure you should test the wss's with a multimeter to be sure its not one of them. So the light will only come on if the car is not moving or if you stop? The light is not on every time you turn the car on only after 15-20 seconds? Sounds very strange to me but I don't know if I understand what your saying about when the light comes on or off. Does it come off immediately after you stop? Also when the light is on the dash ABS should not operate, does it?

SirLapsalot

I remember now that I once had a strange ABS operation complaint on a 964 and ended up finding that the ABS relay was bad. But I can't remember what the symtoms were, I just remember that it was a strange problem and after testing the wss's and pulling the ABS code it indicated something about the ABS relay and after removing it and shaking it it sounded bad and a new relay fixed the problem. I don't even know if our cars have a similar ABS relay but I thought I'd let you know of this experience since no body else has chimed in yet.

Oddjob

They do have an ABS relay in the fuse box, which has been known to fail. Same as what you state - can hear something loose rattling around when you shake it. Symptoms of a bad relay could be anything from complete failure, to intermittent faults when hitting bumps.

I have not had the fault problem that Airflite does - fault light comes on if the car is not moved, but does not come on when moving. I agree that it is probably not a wheel sensor. And I assume you dont have access to any spare ABS parts (from another car) to swap for trouble shooting? Could try a different relay, but the control unit is a probability.

There is a porsche ABS test plan for the 944, but you need bosch diagnostic equipment to run the tests on the control unit. And most shops do not have this equipment.

SirLapsalot

Yeah I looked at the Porsche testing procedure for the ABS on a 944 and the control unit really can't be tested without the bosch equipment: Bosch K7-ETT 016.00/VAG 1516 So looks like you are going to have to just do a simple test on the WSS's, check all grounds, try to find another known good ABS relay to swap yours with and if none of that solves anything then worst case find a replacement control unit and unfortunately I bet those are not cheap.

Airflite40

thanks for the advice guys...

after I did some poking and prodding the problem has gone away... but I will still keep an eye on it. maybe I should do some "tests" to see it the ABS is functioning. maybe not.