FJ80 evil tail light

[56gambit]

Yup. Pure evil. Well, maybe not quite... maybe just reallly annoying. 91 cruiser has a driver side tail brake light that intermittently stops working which is basically constantly asking for a "courtesy stop" from a police officer. Here's the deal : brake light on driver side is found to be non-functioning when it should be. Pull over, have driver stand on brake, open tailgate and panel by light, wiggle wires - no help. Give body a medium (or even light) smack right next to lens cover and it's back on. 10 minutes or 3 days later it's off again. Got new bulbs, no change. Ordered up a replacement harness and installed that thing - thought it was all good, but soon enough have the same problem !!??. I've spent plenty of time searching online for schematics that might show me something I'm missing. What am I missing here? I've pulled the harness along with its associated bulbs from the lens to wiggle the mess around trying to make the problem happen in my hands, but no luck. Is there a ground separate from the harness? If there is, I can't find it. Is the 12" tail harness and the bundle it connects to all that there is to work with here? There's no tow kit, so that's out... what is the deal? BTW the pic is from when (via the police) we found our stolen rig up an impossibly steep hill out in the woods.

 

[56gambit]

Reading this quote from elsewhere... "Power goes from the brake fuse to the brake switch to the brake bulbs (which are wired in parallel) to ground." This is the ground I'm looking for. Can't find that ground..

 

[artech]

Aren't these lights switched on the ground side? Maybe you're looking at it backwards. I have the 96 wiring diagram and my 95 has ground side switching for most of the lights, but I'm not sure how the 91 was set up. Ground would be one of the body ground straps up in the engine compartment.

A smack next to the fixture sure does sound like a connection issue though, maybe one of the mounting screws for the assembly is electrically connected? Hard to see what else would result in that smack-fix working. Or can you smack the body anywhere on that side and get the same result?

 

[jeffro109]

Mine does this, on both sides no less.

My latest "fix" was to take the bulbs out, and sand the connection points down in the socket and sand the little nubs on the bulbs.

 

[itbrokeagain]

The grounds go to a 10mm bolt right about in the center on the rear of the body. I can take a picture tonight when I get home if you need me to. I had wiring issues and was tired of breaking lenses so I moved my tail lights into the tailgate and made my own harness. I have not had any issues since

 

[56gambit]

Thank you all for the input so far. So, here's what troubleshooting has been done over time so far: Upon first noticing brake light was out we gave the lens (or right next to it) a slap - light was back on. Sometime later it happened again so we pulled the cover and, while standing on the brake, found we couldn't wiggle the bulb into turning off again. Pulled the bulb, did some light sanding to the connections on it as well as on the ones in the socket. Next day, bulb was out. Removed tail harness from lens and just started playing around with it while brake pedal was engaged. Couldn't get the bulb to turn off. Also, should be noted here that the harness wires go straight toward the front of the rig without any diverting to the lens area as ground (?) so maybe there goes my loose ground connection idea. Next step was to go nuclear and disassemble the socket and re-solder the guts of it. Went back to driving, again went back to slapping the lens. Ordered up a replacement harness... had to mickey-mouse the mismatched connectors together ... thought that solved it. Nope. I think I need to build a build a contraption that allows the driver to yank a cord that has a hinged slapper by the tail light!? I'll be taking the whole mess apart again this weekend to look around for the grounding point that ibrokeitagain is talking about.. Thanks!

 

[gothodgie]

take a look at this plug in the DS quater panel area... it had a couple nasty pins in it that was causing my problems... i actually had to jump one wire around the plug...

 

[itbrokeagain]

This is the ground I was talking about. You can see the trailer hitch for reference.

This is my entire rear lighting harness. The ground is in the upper left corner

 

[ChiTown]

Do you have trailer wiring? If so check the adapter in the rh rear quarter panel and the wiring under the truck.

 

[56gambit]

So I did like itbrokeagain said and took a look at the ground near the trailer hitch:

pic doesn't show it so well, but it was plenty rusty. hit everything with the wire brush treatment and, well, so far so good! went from having to smack the tail light a few times a day to no problems in 5 days so far.
Hey - thank you all for the input - and to itbrokeagain, thank you big time for crawling underneath to get me that picture. It was an enormous help.
I will post again about this subject if it goes out again.
Thank you!

 

[56gambit]

Well, as promised I am posting again as the DS brake light is going out again. Planning to use mirrors today to try and see what the heck we are missing behind that panel. The connector that gothodgie shows in his picture above will get another good look, but I recall that thing looked plenty clean. Plus, I seem to remember wiggling that thing around once while the light was out without success, yet the smack on the outside did the job. Sigh. Will update as I go. Thanks.

 

[blkprj80]

Check the crimps on that ring terminal real close too. You should be able to pull on the wire a bit and not have it pull out (or stretch the insulation). If it does, you may have found the problem.

Have you checked the 3 wire connector at the taillight? Maybe some grunge hiding inside there if you unplug it.

 

[Hoosier Daddy]

Wait, I'm missing something. Have you narrowed down whether the problem is lack of ground versus lack of +12V at the socket?

 

[itbrokeagain]

Maybe replace the bulb and put some dielectric grease in the socket? I would also try to find a new socket and splice it in. I will look tomorrow but I think I tossed mine when I moved my tail lights

 

[superjuice]

I have the passenger brake/running light out on my 97 and have tracked it down to a bad ground at the socket. The ground wire was good but the connection was bad. I stripped back the ground, bent and soldered it to the socket, then slathered it with dialetric grease. All is well again, HTH

 

[Harry]

I had exactly the same problem as superjuice with my RH reverse light. Re-soldered ground wire connection to the socket and all fixed.

 

[Str8Razor]

I have the passenger brake/running light out on my 97 and have tracked it down to a bad ground at the socket. The ground wire was good but the connection was bad. I stripped back the ground, bent and soldered it to the socket, then slathered it with dialetric grease. All is well again, HTH

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@tmxmotorsports I guess this is the fix for mine, damn thing went out again today..

 

[RonSwanson2020]

I have the passenger brake/running light out on my 97 and have tracked it down to a bad ground at the socket. The ground wire was good but the connection was bad. I stripped back the ground, bent and soldered it to the socket, then slathered it with dialetric grease. All is well again, HTH

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Yes! This
That’s exactly what fixed mine as well (though my soldering looks nowhere near as clean as yours!)
The white wire holding ground had rubbed itself shy after 300K or so, this was a cheap, simple and lasting fix.
Try wiggling the wire with a weight on the brake pedal to see if this works for you as well. Mine lit up when wiggling, indicating the bad ground.
To be clear, the signs were:
-Driving lights working normal.
-PS brake light/ driving light turned off when pedal engaged, while DS normal.

 

[Speedwyre]

Thank you to all that have ventured into this one before me on this thread! Had the same problem (FZJ80). Five minutes on the internet, twenty mins working on it, and another twenty mins pussy footing around, and it's fixed! No way I'm figuring this one out in less than a day otherwise.