Shawnliew88

Hi guys, was driving today with the club member and when I got it to 190kmh the light for the differential control and antilocks show as off on the display panel and it went away immediately instead of staying on. Is it a indication of low fluid level in the differential ? And brake fluid? Thanks

Arnoud

One possibility is a semi-loose connection to the PSD-unit pump motor: if loose or the PSD-unit pump motor actually being permanently damaged (= typically meaning 'fried' short circuits in the electric motor coils) then a warning is shown for both the PSD and ABS being off.

PSD pump motor should measure around 2.7 ohm in static resistance, when being OK.

27th May 2013 edit: I remembered WRONG, the correct information is:

It is the PSD-unit solonoid valve connector that might cause the problems with also the ABS fault light coming on, and has a typical nominal resistance of 2.7 ohm.
The PSD-unit pump measures around 3.5 ohm when the coil wires are still OK, however: even with the PSD-unit pump coil wires measuring OK for resistance the pump itself might still be seized.

spock04

Your PSD pump motor is tucked in behind your left rear wheel well. had the same problem= new pump actuator solved it, spendy for a new one. many used to be found.

Shawnliew88

Thanks guys for the feedback! I took it for a drive ltr on but no problem came back on but gonna check everything out back at work !

Tails

Car Model Year, series and whether it auto or manual will allow allow us to give you assistance.

Shawnliew88

1990 928 S4 auto , drove around today and the light nvr came on again, yesterday when it came on it stayed for few seconds then it went back to normal

Tails

There is a full description of the PSD unit in the Technical Service Manual for the MY 1990. I would recommend that you obtain a copy of Jim Moorehouse Technical CDs available from Roger at 928sRus and you will have all that you need on your 928. In addition I would suggest that you undertake a service on your PSD unit. There is a procedure in the Technical CD mention above and there is another procedure written up on the Porsche OC web site. If you cannot obtain these tech manuals or write ups I would suggest that you have you PSD service by a technical competent Porsche Specalist.

Note the PSD is interlinked with the ABS system.

Shawnliew88

Thanks , yea I notice that the anti lock light come on as well. But I assume it will still be safe for town drive?

Arnoud

Lots more PSD-unit information in this thread:

https://rennlist.com/forums/928-foru...procedure.html

Arnoud

By the way: re-reading my old thread makes me realize that in my above initial answer I provide WRONG information.

It is the PSD-unit solonoid valve connector that might cause the problems with also the ABS fault light coming on, and has a typical nominal resistance of 2.7 ohm.
The PSD-unit pump measures around 3.5 ohm when the coil wires are still OK, however: even with the PSD-unit pump coil wires measuring OK for resistance the pump itself might still be seized.

Randy V

wrong thread