The ASC and the ABS are run by the same computer which is located under the glove box, closest to the speaker panel. They both use the speed sensors on each wheel to detect slippage from acceleration or braking. The ASC tests itself on each startup by actuating the cable that is supposed to be attached to the secondary throttle body to see if that TPS gives signal that it is moving. If the actuator motor / resistance is not plugged in as well, it will trigger both the ASC and the ABS lights.
The ABS system also checks to see if all sensors are there and with the proper resistance, as well as pump solenoid readiness too. If ABS light is on at startup then you have a bad sensor, fuse, or possibly pump. If the light goes out after startup but comes on when moving then you have a bad sensor.
If I were you I would test all sensors to see if they are good. If all test good then you need to verify that the wiring is good to the computer by testing each set of pins in the harness for the same resistance the sensors are showing. You will need a wiring diagram to know which pins to test for each sensor. If all that tests well, then you either have a bad pump, relay, or computer. You have to systematically eliminate each potential source of a problem to get to the bad part. Electrical issues can be a huge pita and time consuming, but they are all traceable. Start with the easiest stuff first like fuses and sensors and know not guess they are good.
Also just wanted to verify that you shimmed the rear sensors if you used e30 axels, otherwise both rear sensors are junk due to rubbing against the ring. |