ABS PSD Warnings after bump on '90 GT

malcolm;7247 wrote: no worries Stan.......beyond the relay Id look at the controller and the ABS sensors.

We are a captured audience for ~4 mths......damn winter:eek:

I swapped the relay with a spare I had, no change.
I guess I will review the sensors more thoroughly now.

I also found my special positive battery cable bolt (that has a fixture for 3 wires to attach) is a bit stripped). I wonder if it could be causing an issue. I will replace it as well, but the car starts fine and I would suspect other electrical issues is this was causing the problem.

Stan,
I am awaiting your further diagnosis on this issue. My '94 does the exact same thing. I also have been wondering what the two systems have in common that would be causing this.

Stan.Shaw@Excell.Net;7243 wrote: Since getting my '90 GT back from service, the ABS & PSD warnings are displayed apparently after the first significant bump. Often they display at the same time, but sometimes the PSD followed by the ABS.

I am presuming it is a loose connection, and more likely rear of the car related since I don't think the PSD would care what happens at a front wheel. Any thoughts on what connections and where to check? Perhaps removing the two grounds at each rear wheel to start? They seem solidly connected when tugged at a bit.

Stan you say when you got it back from the service this started. Was the light on before? If not, is it possible the bat went dead in the shop on them, or that they boosted the bat.

but

Lets think now, if they had it on a lift to change oil, what could have changed?

If the wheels and suspension hung down? what could have been pulled loose?
What kind of connections are around the diff for the PSD.

Look closely at the ABS cables/sensors following along every mm for a tell tail sign where it may have snagged when the car was lifted. I would not rule out the fronts, look close with a light.

I dont know our ABS system but they are all similar. The ABS and PSD would have to work together as well as the ABS work separate.
What worries me is if they somehow fried the module by boosting the Bat.

Unbolted and clean both rear speed sensors, and also unbolted and cleaned both ground connections. result: no change in symptom.

with a good dvm check resistance between sensor termails then each terminal to ground.

dont have specifics in front of me but readings should be ~20k ohms (infinite) to ground

found it:

Acceleration sensor under you seat is gummed up. Do not replace it, do not screw it up when you take it apart. It's a $1500.00 item they developed for the 959 and it made it's way to the C4 and our cars.