Headlight problem? I'm stumped! (1 Viewer)

[KDM]

I’ve read thru the posts regarding the headlights and combo switch, etc. I ended up replacing the combo switch, relay and repaired a broken wire to the license plate lights in the tailgate. There is power to the headlights.

The problem persists, whereas, when I just turn on the headlights all dash and indicator lights come on, as well as the fan motor, auto transmission temp indicator light, and when put into gear the horn also sounds! (relay makes noise when doing this)

The only thing that seems to work is the parking lights only. When I replaced the relay the lights and hi-beams came on for a minute, then again started symptoms above.

I’ve read that the relay can be reset by detaching the battery for 10 mins. The only thing I can think of to isolate the circuit is to pull all accessory fuses then see if condition is same or returns when I put each one back in. I’ve looked at the wiring diagram and checked every bulb and wire that I could find to no avail.

Has anyone ever seen this kind of thing? I’m stumped and about ready to take it to my mechanic. Thanks, and this is an awesome forum and I’ve been a proud FJ62 owner for about 8 months! Any clues will be greatly appreciated..

 

[orangefj45]

Start by isolating the circuits.

How long has it been doing this? Is the harness "molested" or all original?

Georg @ Valley Hybrids

 

[Heartworm]

Under the dash there is a "collector" junction fitting where a whole lot of small ground wires are combined into one larger wire that goes to the body and completes the ground. When that plastic junction fitting gets fried, all sorts of weird dashboard light symptoms occur, not always the same in every vehicle, but all caused by the same basic problem.

 

[orangefj45]

You probably already know this, but the ground wires are white with a black stripe ......

 

[KDM]

Thanks for the advice! It's been going on for a couple months now. I'll check the collector of ground wires under the dash, when I locate them. So far I've only checked the one under the steering column.

 

[KDM]

Oh yeah, and as far as I know the wiring harness is all original.

 

[slcfj62]

See if this helps.

https://forum.ih8mud.com/threads/headlight-troubleshooting-thread.423985/

 

[sfd60]

Mine does the same thing and yes they are correct there is a collector in the dash behind the Speedo and mine caught fire. Have been trying to get it fixed

 

[KDM]

Sorry for the delay on posting an update, however, the head gasket decided to blow on this FJ62! Now that I got that done, I'll try and narrow down the problem. Thanks for the tip sfd60, I'll look behind the Speedo! That's one place I haven't looked, even tho the dash is halfway out.

Looks like a headlight wire harness upgrade is in the near future...

 

[KDM]

I took the dash panel completely off, and still haven't found the elusive "collector" junction of ground wires yet. But I did find some fried wires behind the Speedo in what looks like the main wiring harness. I'll be working on this more tonight.

 

[KDM]

It looks like there's 8 ground wires in this fried connector. How would one re-wire this? Here's what I found:

 

[Output Shaft]

Wow.
I suspect I have the same issue going on with my ground junction (everything is kinda haywire in my dash too).
Thanks for sharing the pic.
I'm curious what others have done about this too.

 

[sfd60]

Yup that's what mine is to

 

[sfd60]

Question though, did you recently just put a new radio in or New headlights

 

[Output Shaft]

Now I've got one of those burnt plug pictures for posterity too!

Thanks @Heartworm and @KDM VERY MUCH for posting your suggestions and picture above, It helped me find my culprit. That ground junction was the problem on my car too. All works perfectly now once that ground junction was disassembled and cleaned up.

Yup, when I was a younger moron, higher wattage H4 headlights (100/80) were installed using the stock wiring harness instead of remote relays (who knew about remote relays 25 years ago?) and a decade or so later, they burned up this ground junction. It seems like everything in the dash grounds through this junction.

Lesson?
Gotta upgrade the headlight wiring harness with remote relays if installing higher wattage headlamps.... and should be done anyway even if using the dim stock sealed beam bulbs.




Thanks guys....

 

[KDM]

I ended up splicing, solder, and heat shrink. Now everything works again. Err, yes I did recently install a new radio. BTW, the new radio/cd/DVD player is the new Pioneer App Radio and it fits perfectly in the console where the stock radio/cassette player was.

 

[Output Shaft]

Yes, good to fix that joint. But you didn't fix the cause of the problem:
There is too much current from the new radio (or something else) flowing through those dinky wires. The old burnt ground junction was the messenger.

Unless the radio (or something else) is wired independently of the wiring harness with larger gauge wire with a proper fuse, something like this may likely happen again at the next weakest (inaccessible) link... and next time it might start a fire.

 

[KDM]

Thanks for the advice! That's the plan, to isolate the radio on it's own circuit and upgrade the headlight wiring harness. The wiring/lights were fine for a good 6 months after the new radio was installed. Then right before the wiring fried I put in new headlamps (sealed type), then soon after that hooked up an RV trailer and trailer lights. It didn't take long, just moving the RV trailer around for about 5-10 mins, and then it was lights out!

 

[sfd60]

KDM what was your verdict