Scamper

Hi all,

I have been systematically working through Adrians book to fault find my ABS/PDAS light problem on my 90 C4 Coupe.

Whilst checking the resistance of the ABS solenoid valves i got the following readings
Front left (pins 1&2) 0
Front Right (pins 3&4) 1.19
Rear (pins 4&5) 1.19

So it all points to a problem with the front left.

Does anyone know what I should do next?
Can this be fixed?
Do I need a whole new ABS valve control unit (mega££££££'s)?
Can these units be refurbished?

I realise this is a specialist job and dont really think I can tackle this myself unless someone has experience of fixing this....

porsche356sc

Hello,

I´v got the same resistance result on my abs, and i also dont know what to do next.

Sten

Are you reading the wiring diagram correctly? Mine shows pin 4 as the common, so 1-4 Front Left, 3-4 Front Right and 5-4 Rear. Check for corrosion on the pins and wiring from the connector field, and internal corrosion on the Valve Relay (the larger of the two).

Sten

Valve Relay is part no. 928 618 931 02, Bosch part 0 332 002 173

Pump Relay is part no. 928 618 930 01 Bosch part 0 332 002 171

Both are (briefly) energised as part of the ABS self check at start up.

Scamper

Thanks Sten,

the pins to check are straight out of Adrian Streathers book so I think it should be right..

I will look into replacing the relays, but dont want to go down the road of replacing of parts without any guarantee that thats the problem.

Are the relays for a C2 the same?? I know where I can get hold of someones to check!!

Ade

Sten

Looking at the wiring diagram for a 90 C2, the ABS hydraulic unit is identical so the relays should be the same. Also check the condition of the earth point, and condition of the pins on the ABS Control Unit (carefully - it's about £3000 for a new one!)