Please help, running lights, fuses

Duffinatur · #1 (**permalink**) 06-06-2009, 09:50 PM

Hi all,
I have been having problems with my dash lights and running lights popping fuses. I've disconnected each light, and the dash is completely out of the car (no dash lights hooked up) Without any lights hooked up, the second I pull the parking light switch, pop goes the fuse. I've inspected the wiring that runs behind the dash all the way to the fuse box and don't see any frayed/cut/loose wires. I lent my multi meter to a friend and won't get it back for a while so I can't test that way, but I do have a 12v test light. Any suggestions?
Could I have a bad relay? Maybe a bad headlight switch? A short in the harness? A grounded wire somewhere?
Thanks in advance.
Duff

strictlypersonl · #2 (**permalink**) 06-07-2009, 03:49 AM

Disconnect the parking-light and headlight wires from the head/park switch. Does the fuse still blow when you turn the switch on? If yes, bad switch.

Reconnect the headlight wire. Does the fuse blow now (if it ddin't before)? If yes, bad switch.

Otherwise, you'll have to trace the parking light wires to find a dead short.

Duffinatur · #3 (**permalink**) 06-07-2009, 04:38 AM

tried it a few times and it blows the fuse, thanx for the tip

Blas · #4 (**permalink**) 06-07-2009, 07:08 AM

"...I've inspected the wiring that runs behind the dash all the way to the fuse box and don't see any frayed/cut/loose wires."

it's just a ground at the switch right? The indicator bulb is powered, and the switch only breaks the ground to the bulb?

Another thought....
Is you switch a "grounding" design? If you hook power to it and then activate it - it's a dead short...
Maybe post a photo of the install.

EDIT: Think I posted this to the wrong thread - sorry...

Michael C Henry · #5 (**permalink**) 06-07-2009, 10:00 AM

I used a trick I came up with I used a 12V test light in place of the fuse. It acts like a capaciter in your power supply, not letting anymore current through than the test lights bulbs filament would let through.. With this limited power off, disconnect all the wires from the light switch except for the power supply Turn on the electric power (I'd just dissconnect and reconnect the test light). With all the load wires removed from the switch the test light should be off, if its on either the switch has an internal short or there is a short between the power supply and the switch. basically power is going to ground without doing any work(resistance)With everything connected and workingcorrectly the test light would be really bright but the actuall car lights would be dimm as the 12V test light wouldn't let enough current through to operate as usual. happy testing.

Duffinatur · #6 (**permalink**) 06-09-2009, 06:03 PM

Thanks, I ended up re-connecting everything one wire at a time to see if I could find a short. Everything behind the dash has male/female terminal connections so I could remove it easily without crimping or soldering. It turned out to be a bad headlight switch. I'm not EXACtly sure why the switch went bad but a new one fixed the problem. (and I'm more comfortable double checking the wiring to boot) Shell Valley supplies a common GM headlight switch that you can get anywhere, but this is the second one I've had go bad, so I bought a spare and threw it in the glove box until I can test if I have a surge or something else.

Thanks for the tips folks.

See you in London.