Headlamp Switch Harness Replacement - Help Please

[gofast00]

So I have the dash/running lights not working (intermittent, actually) issue on my 89 GM. I reached up into the dash behind the switch and basically wiggled shit around while doing same from front of swich, and was able to get running lights back on. Then they were off - then I did the same and got them back on.

I'm assuming from threads I've read (and a suggestion made to me when they were just intermittent) that the harness needs replacing.

Can someone point me in the direction of where to get one, and what's involved with replacing it? Is it done from under the dash (ouch, my back) or through the dash after trim removal?

Brad

[nfldfordltd]

Have you tried replacing the switch itself? I would do that and check each wire on the switch plugins. It's pretty rare an entire harness needs to be replaced unless it burned or something severe like that.

[1987cp]

Agreed, seems odd that the whole harness would be bad. IIRC, the plug/switch ought to get toasted before the wiring does. It's a bad setup, sending all current for all exterior lights through the switch in the dash instead of relaying them like a sensible system would (hence headlight relays as a common upgrade). Worse, all current for low and high beams also goes through the multifunction switch on the steering column!

Headlight switch removes from the rear. There's a funny button on the side you push in to release the plunger, then take the collar off, and after removing the dash trim there are 2 (IIRC) screws going through the dash shell into the switch body. Remove those and the switch can be carefully snaked out from behind.

Once you get the switch out, it's an easy matter to poke at the harness to make sure it still works right.

[gofast00]

Well, it looks like pulling the switch is in the future to find out. I have seen that the headlight connector (the big white multi-wire jamski) can fry, and suspect that may be it due to the intermittent nature: it's intermittent when I screw with the wires in the dash, but not when I screw with the switch itself. Total drag, as it's extra crowded under there due to the original owner installing trailer brakes and THAT wiring is jammed up there too.

[1987cp]

It's crowded under there no matter what - FAIL to Ford for running every wire in the car through the dash area left of the steering wheel.

[GM_Guy]

Have you tried replacing the switch itself? I would do that and check each wire on the switch plugins. It's pretty rare an entire harness needs to be replaced unless it burned or something severe like that.

I'm sure he means the headlight connector pigtail. That goes far more often than the switch. The switch is a red-herring repair as far as I'm concerned.

Can someone point me in the direction of where to get one, and what's involved with replacing it? Is it done from under the dash (ouch, my back) or through the dash after trim removal?

Any parts store. Napa, Autozone, Rockauto, etc. One size fits practically all.
Yes, basically it is done from under the dash. Ford does not give you any extra wire, you get just enough to see the ends of the wire barely poke out from below the dash. Nothing impossible, just a pita (I soldered & heatshrunk each one, so it took a little longer than butt crimps).

Alex.

[sly]

I had the joy of replacing a 92 vic headlight switch. The circuit breaker went bad. That has to be the worst design for a switch I have ever seen. so glad my 93 has the relay mod done to it.

[sxcpotatoes]

I've still got that '91 that the parks/running lights will not work on, I've got a total of 3 headlight switches that can't all be bad and I had a local shop replace the plug (didn't fix it). Any relay wiring instructions/thread around on here so I can finally drive it at night?

I bought the Electrical/Vaccuum Troubleshooting manual for it but have been too lazy to tackle it.

[Piece-it pete]

Are all your parking lights out, or just the front? I gave up and ran a relay off teh headlights, it turns the front parking lights on with the headlights

Pete

[89gm]

maybe this help
http://www.grandmarq.net/vb/showthread.php?5806

[sxcpotatoes]

Are all your parking lights out, or just the front? I gave up and ran a relay off teh headlights, it turns the front parking lights on with the headlights

Pete

Front and rear running lights are both MIA. Automatic lamps work fine too for just the headlights.

Thanks 89Gm, I should've actually tried searching for the relay thread instead of being lazy.