drewmurray1

Hi to all,

New to this site and wondering if anyone can help.

Got a problem with my 928 GTS 1994, When i fire it up everything is okay but when i go in drive the PSD light comes on and the speedo fluctuates on its own.

Ive gone today to test the rear wheel speed sensors and got the following readings;

Between the 2 connectors going to the wheel speed sensor

Back left - 1012 ohms

Back right - 1010 ohms

Now i measured the resistance between each pin and earth and got the following;

Back left pin 1 92 ohms, pin 2 - 1029 ohms

Back right pin 1 9 ohms, pin 2 - 1013 ohms

Am i right in saying that measuring between each pin and earth the resistance should be infinite? does this mean i may have a build up in the wheel speed sensors causing it to earth out?


Any help would be greatly appreciated!!

davek9

the easiest way is to test at the ABS controller's connection under the left side parcel shelf to see if the signal is getting to the computer.

We have done this twice on two of Andrews cars (Coke 86.5 and the SC Euro), the Coke car turned out to be the ABS Relay, the Euro was a broken connection inside the Engine compartment.

You need to use a O Scope, and look for a wave as you spin the corresponding wheel, pin-outs are marked in the Service Manual.

If you don't own a Scope maybe you can borrow one or just make one out of a PC/notebook (free software called PC Scope) that's what we do here in the D

Edit: we also noticed the wave Peek to Peek varies on some sensors, didn't affect the ABS working, could be the diff in resistance you noted, we did take them apart and cleaned them and it didn't change the wave form.

Dave K