Seeking advice on loss of tail/brake lights (1 Viewer)

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Aug 30, 2015
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Pensacola FL
I recently had a local audio shop trouble shoot a few minor issues with a back door speaker and 3rd row subwoofer wiring issue. Plan was speaker replaced and new wire run back to the sub- easy stuff.
When I picked it up, the Viper security fob didn't work so the tech realized it and solved it quickly with some "wiring" fix.
All seemed fine but I was made aware by someone driving behind me that I had no brake or tail lights. I also noticed when I pushed the Viper button to lock the doors, all normal lights blinked except the rear taillights. So I figured it has to be related to the work done at the shop. I took it back yesterday, they checked all of their work to make sure nothing was unusual and they checked voltage to the rear lights and found no reading. The top of tailgate brake/running light works normally and both blinkers work fine.
Shop wants to keep it until their more "experienced tech" can trouble shoot it tomorrow so maybe he will discover the gremlin, but so far they think its unrelated to any work they performed and maybe they are right...
Question is what are the typical reasons both tail and brakes lights might go out at the same time when fuses are all checked as good? A previous owner has converted most all bulbs to LED and I hear those can create weird problems but all bulbs work when I tested them in working sockets (rear blinkers worked so plugged all bulbs into that and worked fine).
Any advice is appreciated.
PS- I'm new to the site so forgive me if I'm not fully versed in how this all works but really love having some experts to advise me (at least way more expert than me!)
 
My guess is they used an existing ground for their wiring and didn’t get it tight or the wire broke. What year is your 80? Look in the resource section here and download the manual and the ewd. You can find the wiring diagram for the brake lights and look for the ground locations. That would be my first check. Good luck it sucks when you pay someone to work on your truck and it gets messed Up.
 
I second what Voodu3 said.
Sound like a ground issue.
 
Check for damaged wiring harness, under the rig, left side rear corner. I have seen tail pipes crunched on the trail result in exhaust gasses diverted and melting wiring harness in this area. Loss of brake/tail lights can happen then. Just a possible that is easy to check.
Edit: @Greg Woodfin RIGHT side rear corner. Doh
Mark...
 
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Voodu3
1996.
I will do some digging to find that resource. I’m no electrical engineer but sounds logical that some step they did changed the ground / voltage supplying the rear lights so maybe they can figure it out. Surely too coincidental, has to be related
Didn’t make sense that blinkers and the center light and even tag light works tho. Maybe they are on a different wiring track.
I’ll have them check the wiring harness Mark.
Thanks for the guidance.
 
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It does make sense to me brake light are on a separate circuit, unlike American cars which turn signals and brake light work together.
L.E.D. Need the correct polarity were standard bulbs will work wired either way, another thing to consider is Toyota uses the ground to switch things instead of the hot or powerline.

Another thing to consider is where the trailer wiring harness connects underneath the car it’s a known trouble spot worth checking out.

My money is still on a ground issue
 
Your hopper is disconnected, it is the little box in the right rear it probably has your trailer wires in it too
 
Toyota uses the ground to switch things instead of the hot or powerline.
The only lights that are a true switched ground on an 80 Series are the high beam bulbs.
While the tail lamp relay logic is fired from a switched ground, the bulb sockets themselves have a fixed ground and are fed a switched +12 from the relay.
 

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