Headlight very dim

[Detroit Style]

I recently picked up an 87 GT. The headlights are very dim, and the blinkers blink very slow. The guy before me put aftermarket fog lights in, wired them to the headlights. Also, the switch has been messed with. There is no parking light position. The head lights come on with the parking lights on the first click.

Before I rip out the whole harness, is there any areas I should look at?

Are all the grounds for the lights tied in together, or are they separate?

 

[HISSIN50]

You're going to want to redo that wiring anyhow. I dont even know if the parking light position has a thermal overload breaker on it (or if that's just on the headlight position).

Be prepared to find a burned red/yellow wire from the hdlt switch to the MF switch. Add a relay to the fog light circuit (and any others you desire). This will unburden the switchgear.

Check the grounds at the front clip. Use your meter to test the voltage reaching the bulbs (leads biased across the low and ground, or high and ground). Then do the same test to check voltage drop with a load.

Good luck.

 

[Detroit Style]

Well, I pulled out all the extra wire that was there. Axed the wires running from the headlights to the fog lights. Re ran a length of wire from the switch. They are back to being bright. The headlights still come on in the parking light position though.

I also took a close look at the harness, it has been opened up before. Im thinking Ill either re wrap in it the corrugated tube, or just buy a new harness. At some point, Ill wire tuck the whole engine bay anyhow.