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classictech
classictech, Auto Service Technician
Category: Car
Satisfied Customers: 220
Experience:  20 years On-Job experience in troubleshooting drivetrain driveability issues
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I have a 1996 GMC Jimmy. The ABS light and the Brake light ...

Customer Question

I have a 1996 GMC Jimmy. The ABS light and the Brake light both came on at the same time. While those lights are on the windows, radio, heating and airconditioning systems all will not work. When those lights go out those units work again. I have 189,000 miles and I''m guessing the computer maybe going bad. Will have diagnosis done on Monday but, give me your opinions.
Submitted: 8 years ago.
Category: Car
Expert:  classictech replied 8 years ago.

Hi from JustAnswer!

It's likely that a circuit breaker servicing all these systems is tripping due to a short circuit. Since the ABS system uses a different circuit for warnings, the lamps light because it also detects a loss of voltage.

Unfortunately, so many circuits are attached to this particular power feed that tracing them one by one for an intermittent short circuit to the body or a wire-to-wire short is the only procedure to do from this point. A shorted power window switch, wiring shorts inside the door pillar passthru, a faulty blower moter and several other things will cause the same result, a power failure to many high-current applications. All of them will have to be checked to determine which is causing the outage. The good news is it's rarely more than a single part that is causing all the trouble.

 

Customer: replied 8 years ago.
Reply to classictech's Post: I did the troubleshooting over the weekend and ended up replacing the ignition switch (try to figure sometimes) which eliminated the problem. Thanks for your response and if the ignition wasn't the answer I would have accepted your response. (a co-worker of mine told me had a problem similar and the replacement of the switch fixed the problem).
Expert:  classictech replied 8 years ago.
Good job! Thanks for checking back,