Cascade Crew

Xophertony

so i am driving my GF to work this morning, and as we are in line at starbucks SMOKE starts to spill out from under my dash, by the time i pull the lower panel the smoke has stopped. my LT BLUE wire on my brake switch has burned in half. i now have no brake lights.

after dropping her off at work the diagnosis starts. using an extra harness connector i rebuild the brake light switch wires. the problem continues.

if i plug everything in as it is supposed to be, and close the brake light circuit (pedal depressed, brake lights on) the wire starts to heat up. if i unplug the bulbs, this will not happen. this seems to point to it NOT being a short to ground. but i went ahead and pulled out the interior and looked at the wires anyway. no shorts.

i have tried using a different brake pedal switch. problem persists.
i have tried using a different steering column turn/hazard switch (part of brake light circuit in GTA/TA). problem persists.
i have replaced all the bulbs. problem persists.
i have tried bypassing the pedal switch, and wire path between it and the column switch with a length of wire. problem persists.

i have disconnected the ground wire to the rear lights, problem solved, but no brake lights.
i have removed the bulbs, problem solved, but no brake lights.
i have removed the column switch, problem solved, but no brake lights.
i have removed the pedal switch, problem solved but no brake lights.

synopsis:
i have tested each individual component in the system, by swapping it with a spare. i have tested all wire paths for shorts to ground with a DVOM.
nothing appears to be wrong. yet whenever i allow the circuit to complete, and the lights to illuminate, the wire starts to heat up.

Help me. Sad

Twilightoptics · Posted: Mon May 11, 2009 2:50 pm Post subject:

Turn signal switch.

Power short to ground somewhere.

Xophertony · Posted: Mon May 11, 2009 3:00 pm Post subject:

turn signal switch = column switch. tried it already.

short to ground? i'll keep looking, but i will swear that i have checked every wire. after i have checked them ALL again perhaps i will find my short.

Twilightoptics · Posted: Mon May 11, 2009 4:50 pm Post subject:

Something is drawing more amps than that wire is made to handle. Could be a bulb even. I'd be taking all the wires apart in the looms and looking for some that have melted together.

Al Hasse · Posted: Mon May 11, 2009 6:31 pm Post subject:

I agree with Paul. Something is drawing power to ground and frying that wire. As he stated before, could even be a bulb, if not a bad socket. Since you've replaced the bulbs, that's where I might look. I had a bad side marker socket that kept the dash indicator on for the directional and it took for ever for me to find it.

chevymad · Posted: Mon May 11, 2009 7:41 pm Post subject:

Probably a socket since you replaced the bulbs. Kill one socket at a time. Disconnect or cut the wire somehow til you find it.

No Liggets!

Quasi-Traction · Posted: Mon May 11, 2009 7:44 pm Post subject:

Where's that "brake light switch" you have on the roof console spliced in at dude?

blue89 · Posted: Tue May 12, 2009 6:07 am Post subject:

I'm voting socket. You've verified it was not at the dash.

Xophertony · Posted: Wed May 13, 2009 6:35 am Post subject:

blue89 · Posted: Wed May 13, 2009 6:46 am Post subject:

You said it's fine with the bulbs removed? I'd get a new bulb from the store and put it in a socket one in at a time until you find the problem socket. What a weird problem!

Twilightoptics · Posted: Wed May 13, 2009 9:56 am Post subject:

chevymad · Posted: Wed May 13, 2009 4:52 pm Post subject:

He also said new bulbs and same problem. Thats why i'm thinking the socket shorts out when the bulb is installed.

Twilightoptics · Posted: Wed May 13, 2009 5:30 pm Post subject:

Think Travis was saying to get a new bulb for certain when trying each socket till one shorts.

Xophertony · Posted: Wed May 13, 2009 8:23 pm Post subject:

a bit busy with work, but me next test is to put all bulbs in thier sockets, and remove one at a time until i find the problem socket. then i will replace said socket.

Xophertony · Posted: Tue Jul 21, 2009 1:21 pm Post subject:

update.
i spent several hours since my last post diagnosing. no one socket causes a problem. all bulbs are new. it seems to be a bulb quantaty thing. any more then 3 bulbs casues the issue, regardless of where those bulbs are.

i put a "work around" in place. which was driving around with only 1 bulb on each side. that was working, but this sat i decided to fix the damn thing. i looked at the ground wires first, because come on, it's always the ground. turns out all 8 bulbs (4 per side) have thier own 16AWG wire coming from the bulb socket going to ground. and they ALL meat up and connect to ONE 16AWG wire that runs into tha cabin and grounds near the hatch PPD. well, F that. i cut that sucker out, and soldered all the 16AWG wires to a much bigger ground wire (10-12 AWG) and ran THAT to a ring terminal to one of the PPD unit bolts. i now have six bulbs functioning with only slight warming of the power wire. i will test it with eight once i replace the two bulbs i broke. the ground was probably not the issue, but it has helped.