My car is blowing fuses. It only blows a fuse when I turn on the ignition. The fuse can blow today and not again for a week. A few days ago I changed 3 different fuses one after the other. I change the fuse at the same spot each time, never a different one. Any thoughts?
Then you have a short, can you supply more information of the fuse number
February, 8, 2013 AT 12:07 AM
Look at the wiring to the oxygen sensors to see if a harness fell down onto hot exhaust parts and is grounding out.
When it continually blows new fuses you should not try to stop that from happening because then there's no defect to find. If you can keep it in the defect stage, here's a trick that will let you avoid watching new fuses blow one after the other. We both know that isn't going to help you diagnose anything: Replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a 12 volt light bulb. A brake light bulb works well. If you need the circuit to pass more current, as in when the test bulb is real bright even when there's no defect at that time, use a head light bulb instead. That will limit current in the circuit to a safe 5 amps. A brake light bulb will only pass about 1 amp. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it's not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.
To add to this, it is most likely the fuse is related to the automatic shutdown (ASD) relay and circuit. That relay only turns on for one second, not giving you enough time to do anything, and again during engine cranking, making troubleshooting impossible. The best approach is to remove the ASD relay from the socket, then use a stretched-out paper clip to jump terminals 30 and 87 in the socket. The ignition switch doesn't even have to be on.
If the test bulb is full brightness, the short is present and you can disconnect things to see which circuit makes the current go down and the bulb get dimmer. Unplug the coil, distributor, or coil pack, depending on which engine you have. Disconnect the two or four oxygen sensors. Disconnect the injector harness. You don't have to unplug individual injectors because a shorted one is extremely rare and won't cause the fuse to blow. The common wire feeding them, however, could be grounded. One of the small wires on the back of the alternator is on the same circuit but I've never heard of an alternator problem causing the ASD fuse to blow. If you do not have a separate fuel pump relay in the under-hood fuse box, the pump will be on this circuit too. They too rarely short but the wire going to it could be rubbed through and grounded.
This all assumes it is the ASD fuse that's blowing. Look at the label under the fuse box cover to identify which circuit that fuse is for.