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I have a 1990 Corvette with ABS Service light permanently on. I have a Tech 1 and have scanned the ABS and get a Code 63 which indicates a faulty module relay which seems to be the most common fault with these. If only it was that simple. The car only has 20k miles on it and relay seems to work perfectly when testing with a multimeter - 12V is switching nicely.
Ive also pulled the pump motor relay and shorted that out and the pump fires up. Seems like the computer is not triggering the ABS.
If I clear the code it comes up again straight away after starting the car.
do you have a FSM? if not, get one. 1990 FSM, section 5E1-36 covers anti-lock brake system (code 63) diagnosis in step-by-step detail. there also seems to be a TSB - 90-430-5, ABS diagnosis revised code 63. google "C4 corvette code 63" for more info. in a nutshell, there seems to be two relays in parallel - pump motor, and solenoid valve relays with signals coming off the EBCM - code 61 and 63. my printer (with scan function) is down, so here's a few snapshots of code 63. hope this helps....
Many thanks, I was confused over the relay and was testing the module relay and not the solenoid relay. Ive just pulled the solenoid relay and I think it is faulty after putting voltage across it ( no clicking heard) - will pop down to the wreckers and get another one to try. Here in New Zealand there are no Corvettes being wrecked but looks like this relay is used in both BMW and Volvos so hopefully a cheap fix!
Many thanks, I was confused over the relay and was testing the module relay and not the solenoid relay. Ive just pulled the solenoid relay and I think it is faulty after putting voltage across it ( no clicking heard) - will pop down to the wreckers and get another one to try. Here in New Zealand there are no Corvettes being wrecked but looks like this relay is used in both BMW and Volvos so hopefully a cheap fix!
I don't think the 90's have the same abs pump as an 86 does, but it appears the same Bosch 2 unit used in 86's was also used in Mercedes, BMW's and Porsche's in that era, I don't know about Volvo's.
It opens up some more parts options if it's correct and your unit was used in other vehicles also. Big thing, go by the number on the respective relays when looking for replacements, not what they came off of.
Here's some info I tracked down while diagnosing my ABS issue and possible alternate sources of parts based on online info.
Bosch Pump Motor Relay 0332002171: BMW E30 ABS Anti Lock Brake Pump Relay 318is 318ic 325i 325is 325ic 325ix
Mercedes W126 W123 W107 W124 W201 relay 0332002171
0 332 002 171 | PORSCHE / AUDI / VW OEM ABS PUMP RELAY
Bosch Solenoid Relay 0332205003; BMW E30 Mercedes Corvette ABS Pump Breaking System Relay Bosch 0332205003
NEW Bosch Relay (ABS) 0332205003 BMW 34511154919
ABS SYSTEM RELAIS VOLVO 740 - 760 - 780 - 940 - 960 / BOSCH 0332205003
Possible alternative for Bosch Module Relay 0332512006: 0332512007. That one has a skirt that would have to be trimmed, but first look appears it may be the same relay in a different housing.
Even found some sensor cables that look very close:
BMW E30 325i Rear ABS Sensor 320i 318i 318is Convertible Touring Saloon M3
Here I think is a new copy of that part from Autozone:
Duralast Brake Sensor - ABS
Image of Duralast Brake Sensor - ABS : Part number SU11958
Part Number: SU11958
Alternate Part Number: SU11958
In case someone else is looking for parts. Hope it helps.
09-10-2017, 04:54 AM
Any ABS brake guru's out there?
