Porsche Enthusiasts Club Forum

Hi everyone I have been chasing a kind of impossible ABS system fault. It's an immediate fail on self test with the car stopped.

Current situation:
I have excluded any problems in the hydraulic unit as I have checked both relays activation by grounding pins 27 and 28, and therefore the pump operations as well (all good). Power on pin 14 will bypass relay and prime pump well.
Pin 15 (alternator) is OK, and powers only on running engine.
All grounds OK. (pins 10, 20, 34)


Weird situation is: I have power on pin 1 all the time that the key is in position 2 (ignition). Shouldn't this pin only be powered on brake pedal press??

Can someone please tell me if I should be getting power on pin 15 of the ABS relay without pressing the pedal (both with the key on ignition but car not running, and with car running), or only with brake pedal press.

Hello,

Im having exactly the same problem. When I last used the car in Dec. it was fine. Now its abs light permanently. Ive got good resistance readings from the sensors, Ive got no problem with the abs relay. Im going to check power to the ecu tomorrow and my feeling is overall that the ecu is no good.