Does anyone know how to tell for sure if an A.B.S. pump is bad?? My 95' STS is running "motor pump circuit" and "low brake fluid" codes. Before I replace the pump and look like an idiot, I want to be sure it's bad!! Is there a way to test it?
Also. The brake fluid sensor is the plastic thing with the wire plug on the master cylinder, RIGHT??? If so, I replaced it with another USED one and it was no good either. Could that be my problem????
Please help?
Alex

 

If you are going to keep car get factory manuals.It contains the answers. Is the 12v to pump? It could be relay.Used parts are always iffy.