Electrical frustration..., This is starting to piss me off. Options

[BMartin914]

So I have a recurring electrical problem in which my front marker lights, rear marker lights and rear tail light do not work.

I have traced down the wiring, see no problems. Cut open the harness and inspected as much as I can see (which is most of it) and still see NO problems (melting, arcing, etc.). Tonight I cleaned ALL the grounds (under relay tray, trans strap, fuse box, etc.). I then pulled all of the affected bulbs and planned to put them back in 1 by 1 until the fuse blew. Didn't get that far. As soon as I pulled the switch out the fuse blew.

This leads me to believe that wires are arcing somewhere, but as indicated, I see no visible melting or arcing. Does anyone have any ideas? I am at the point where I am willing to re-wire the circuit to fix the problem.

Anyone have any ideas before I re-wire this b**ch?

Thanks.

[Spoke]

Does the left side front parking lamp (the other filament with the turn signal) come on? It should be on the same circuit as the side marker lamps. On the 5th fuse, there should be 2 wires on one side of the fuse. One goes to the front markers and one goes to the back markers. The wire on the other side of the fuse goes to the light switch. With the light switch on, measure the voltage of this fuse to ground. You should see 12V on both sides of the fuse.

If you don't see 12V at the fuse, then check the wiring and voltage back at the light switch.

If you do see 12V at the fuse, check the condition of the lugs and push-on connectors for rusting or oxidation.

Since both front and rear don't work, the problem is the common wiring from the fuse box to the switch.

If you pull the switch out, disconnect the battery first. The schematics in my shop manual show a direct connection from the battery to the light switch without any fusing or fusable links. It could get ugly if this wire were shorted to ground.

Do you have a schematic for the vehicle? I've found this to be extremely useful when chasing electrical gremlins.

Good luck,
Spoke


BTW, the problem you're having is an open circuit. A short circuit would cause fuses to blow or lamps to stay on all the time. With an open circuit, stuff doesn't turn on although an open circuit may have been caused by a short circuit which fried wires but this is usually very obvious by the burned wires and smell.