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Blown relay

dan1004dan1004 Member Posts: 2
edited April 2015 in Pontiac
I have a 2003 grand am se1. Relay 19 (under hood) keeps blowing. When this relay blows... parking, fog, dash lights all go out. I've checked all fuses, replaced bulbs, and put in a new relay twice. It works fine for a while then randomly goes out again while driving. The relay failing doesn't coincide with turning on or off the lights. I'm at a loss on what/where to check. A bad wire shorting out somewhere? etc.. Any ideas?

Comments

  • thecardoc3thecardoc3 Member Posts: 5,745
    When you say that the relay is blowing, exactly what is happening? Is it simply going open and no longer turning the circuit on in the controlled side of the circuit? Or is this a problem with the control side that the body computer provides a ground connection for? Has anyone pulled codes from the body computer and/or attempted bi-directional control functions?

    Fuse #15 provides power for the lamp circuit through the relay, one would expect that the fuse should fail first if the circuit is getting grounded and drawing too much current. There have been some cheap fuses that hit the market a few years back that didn't open the circuit when it shorted and that caused all kinds of problems so with that in mind here is how to proceed.

    With a low amps current probe all you need to do is connect around a wire and you can measure the current flowing through it. We would pull the fuse for the relay (#15) and install a fuse buddy with a 15amp circuit breaker in it. Then drive the car and monitor the current in the circuit looking for spikes which would indicate that an excessive circuit load is occurring. From there if spikes are detected with the scope and current probe, additional current probes could be used to assist in dividing the circuit into sections so that the portion of the circuit responsible for the excess current flow could be identified. Then we only have to be labor intensive with accessing a small portion of the circuit.
  • dan1004dan1004 Member Posts: 2
    Thank you for the info. I don't know what was causing what first, etc.. But I have replaced the relay and the dimmer control module (under dash). Now everything has been working fine.
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