OlberJ

Hit my 1st issue with the 928 last night.

Have noticed the ABS light come on when driving previously. Switching engine off and back on has cleared it the couple of times it happened.

Last night it came on, switched off engine, switched back on and still light on. Tried again, same thing so drove it the half mile to missus' house and switched it off and left it for a few hours. Went out to try it few hours later and the battery was dead.

Could hear a motor running constantly even with ignition off and found the ABS unit to be buzzing.

Have read up on the sensors etc but i'm thinking it's probably the relay stuck on due to the constant current draw, even with ignition off.

Couple of questions :

1) Would a 944 2.5 have the same ABS relay? My mate has one in his garage i could borrow the relay to test.

2) Can see 2 different kinds on ebay and the like for replacement, black and grey. Is the grey the later version and the one i would need on a 90 S4 digi dash?


Cheers,
Olie

Bertrand Daoust

Olie,

I changed mine few weeks ago and the part # was 928 615 124 01.
This one should work for you too. Don't remember what color it was.

OlberJ

Ok, i've pulled the relay and the ABS unit is still buzzing away with the ignition off.

Should the relay hold the circuit open or shut in normal operation? I.e if the relay is actually broken will this mean the unit runs constantly or never?

Can i short the points to make the ABS unit stop running?

dr bob

Besides the ABS relay in the central electrics panel, there are two relays mounted directly to the ABS unit in the front wheel house. On LHD cars it's in the left front wheel house. The brake lines and a bias valve connect to the main body of the pump unit in the engine bay. The rest of it is accesses by pulling the main plastic liner, then the forward shield. That shield has foam seals that keep wheel-thrown junk away from the otherwise exposed relays on the unit.

Power to the unit is direct from the battery and alternator with no fuse. There's a terminal block below the unit in the engine bay. On the LHD cars, the cable routes through the gap in the can belt covers above the alternator, passes under the steering fluid reservoir, to the little terminal block. Plastic cover on it IIRC. Disconnect the battery before fiddling with that connection.

OlberJ

Thanks for that. I had the same advice from John (JDSPorsche) on the 928 mailing list.

Just waiting for the rain to go off and i'll remove the 2 relays at the unit for testing. They are in the same place for RHD cars for reference.

Will update the thread when i have replacement relay sorted.