mikehill964

Hi
I have a 91 C4 ABS and 4WD lights and sounder, speedo and rear spoiler not working, I have checked the wheel sensor resistance and the supply fuse all appear OK. The ABS ECU was sent away and returned with no fault found. I have checked the wiring wire by wire and can find no faults. I bought the Durametric tester. It reports ABS ECU failed to initialise, I have checked the connections from the test socket through to the ABS ECU and they are OK.
I'm now at a loss to what the fault could be, anybody have any ideas what I can try next.
Thanks
Mike.

Sten

Check for corrosion on the pins of the ABS and Interlock relays which live on top of the ABS pump. Is the boost pump running when you turn the ignition on?

mikehill964

Hi Sten, the ABS pump runs OK and clears the brake pressure lamp after a few seconds, I have disconnected all the connectors,relays and checked and they all look OK.
Mike.

Dan Jacobs

Mike,
Is the abs/ecu receiving the 12v pos signal from the alternator 61 circuit ? This is what tells the ABS that the motor is running. If it doesn't get this signal it thinks that you merely have the key in the on position
Good Luck,
Dan J

mikehill964

Hi Dan, thanks for the reply, I've checked that circuit and the voltage is fine at the pin to the ECU.