paalw

I have done a lot of maintenance this winter, including replacing all 4 shocks, TB/WP MM/OPG/steering rack bushings etc. The problem was not present when I put the car on the lift late 2017, so this is most probably something I have managed to f"#¤ up myself.

Now, when I start the car up (still on lift, without wheels), it takes about 5-10 seconds after engine starts running, then the ABS error lights up red in the LCD display, followed instantly by the PSD error. The car is always in neutral and hubs are not spinning.

My bet is that the PSD is relying on the ABS sensors to function, and that one(or more) of the ABS signals are not getting through to the brain. Would that be a descent assumption?

What I have checked so far:

Inspected all wheel wells for visible damage to ABS sensors and lines. Nothing worrying found, all looks good. Removed each connector to all ABS sensors and reseated them tightly. No difference after this.
Removed ABS fuse and ABS relay, reseated. No difference after this.
Replaced each rear ABS sensor one at a time with a (probably) good spare one. No difference while doing this.

Any suggestions what the next move should be?

Thanks.

Kevin in Atlanta

This is normal when the car is in the air.

Bertrand Daoust

I had this problem - PSD error lights up red in the LCD display, followed instantly by the ABS error - at start up and it was a bad ABS relay.
Relay in the main panel.

buccicone

worf928

Bertrand is on the right track:

With no wheels moving, the only thing that can trigger both ABS and PDS warnings immediately at start-up is a dead-as-a-door nail problem: Control Unit is 'missing' (remember that PSD and ABS are run from the same box.) Furthermore once ABS goes t*t$-up PSD follows by design. So, diagnosis must start with ABS.

Relay, fuse, unplugged, etc.

That written, the Bosch Hammer or Theo Tool is the next step if the CU is plugged-in and is getting power.

Now, if you are on a lift and in gear, or on a dyno and the rear wheels are moving, then having ABS and PSD pick up their marbles and go home is normal.

paalw

Ok? Explain please. Contradictory to the other replies.

Where is the ABS/PSD unit located?

Mrmerlin

before you do anything else put the wheels on the car ,
disconnect the battery,
then connect and drive it.
Please report your results

Kevin in Atlanta

ABS and PSD walk hand in hand in hand. PSD and ABS use the same sensors. So, I figure it's always a good idea to have the car on the ground before awsuming there is a problem.

Kevin

Ducman82

Up in the air or on the ground, abs sensor fault only happen when the car moves, sees a sensor issues then trips the light. If the abs light is on without the car moving, it's a brain or power problem.

worf928

paalw

Ok - still not solved this issue, but I have some updates.

I have driven the car, that did not help, as I expected. Still the same thing, ABS warning light on from I start the engine, ABS and PSD failure msg in LCD before I start to drive. So - I have tested with a working ABS relay, no change. Tested with a working ABS/PSD brain, no change. So - I suspect there is some kind of trouble with the check signal from one of the sensors. Some ground issue so one of the sensors don't report a signal at startup. This could make sense, because I have replaced the shocks on all corners, and with that came a lot of hammering and **** to get the rear suspesion pins of etc etc. Before I started working on the car, the problem was not present. Can this be the case? If so, Is there any test procedure to check ground/signal on each sensor?

If not, what should be the next move?

Mrmerlin

look carefully at the front ground wires if things moved around as much as you said then the ground wire might have broken.
also test each sensor at the junction block at the wheel well and in the trunk hatch area to see if the signal is present.
I have found this a few times the wire will shear off its plastic connector junction

paalw

Yes that's what I thought might be a good idea. But how do I check the signal? Is there a dummy guide?

Kevin in Atlanta

If the two pin connector that runs to the solenoid switch is disconnected you will immediately get an ABS followed by a PSD error. I know this from my personal experience.

But, assuming that you did no mess around the PSD area then Stan is right in that there must be a short in the wiring.

Ducman82

Check the accelerometer under the seat. I have seen the wiring under the hand brake cover get knicked or cut by the trim screws.