2004 Oldsmobile Alero Blows 40 amp ignition Fuse

Question: I have a 2004 Oldsmobile Alero, 4 cylinder, and a few nights ago I went to start it, but it wouldn't start. The ignition made no noise at all, no clicking to indicate a dead battery, no cranking noise, or anything like that. I could hear the fuel system starting up, but that was all. None of the dashboard lights car on either. I called AAA, and they sent out the vehicle. The person who showed up immediately found it was not the battery, and proceeded to check if it was the starter or something else. He found that it was a shortage, which had caused the 40A fuse for the Ignition Switch Battery to blow. He didn't tell me that specifically at the time, though, and merely said there was a shortage in the ignition somewhere. I had the car towed to Pepboys, and the next morning they said it was the Ignition lock Cylinder, which sounded a bit off to me since I was having no problems turning the key.

Before they did any work on it, we had it towed home and checked it ourselves, and found the problem with the fuse that had been found my the AAA guy. After a ton of research, we figured the problem must be the ignition coil, which we then had tested. The coil was blown and we replaced it. The car didn't start, but the fuse didn't blow and the battery was dead, so we charge the battery. The car was able to start after that, but when we turned the car off again the 40A fuse had blown once more. I've done more research, and found that the problem could either be a wire grounding out somewhere, or the alarm remote could be interferring with the car somehow. The problem with the second theory, though, is that when I bought my car used it did not come with a car alarm remote. Is there anything else that could be causing the problem?

oldsmobile alero

ANSWER:

That is correct. If the car does not have an alarm, that would not be the problem. The ignition coil cannot blow a fuse. An ignition switch or key cylinder cannot blow it either. The ignition switch sends power to most of the car systems. If there was a problem with that, there would be a low voltage problem, not a blown fuse. You have a short circuit somewhere. You are going to need to get a repair manual at least get a wiring diagram, test light and digital multimeter and trace the wiring for all of the components that is powered up by that fuse. It most likely will not be a bad part, but rather a shorted wire.

This can be a very difficult thing to find, so I would suggest taking it to a mechanic and not trying to diagnose this yourself.In order to blow a 40 amp fuse, this would indicate a large wire, probably orange or red is shorted. Checking under the dash for shorted wires coming off the ignition switch would be the first thing to check.

Many times non-factory alarms are installed. Many wires need to be cut and spliced. Then when the system fails, people will have the wires cut and put back to the factory original. This causes a lot of unnecessary wire cutting, re-routing and repairing and is a common place for shorted wires.


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