JamesDINAN

Hi, haven’t found any help on this so reaching-out for help with steps to solve my one brake light not working, frustrating situation.

Both taillights work. New bulbs.
3rd brake light works, left brake light works…right brake light does not.
Other day, I cleaned both sockets with spray in case of connection issue and see no corrosion on any of either. Attempted using 12 volt tester on sockets to look for power to sockets. Turns-out, I did not have a good ground and when I probed left-side brake light I accidentally touched 2 different contact same-time and, the right brake light actually illuminated for a second before blowing 10amp stop-light fuse.Today, revisited probing with good ground. No power to right-side socket (brake only, tail-light yes…same bulb). Not blowing any fuses with the good ground.
I bypassed (disconnected) factory tow package wiring (in case was a short/grounding issue there), and no change in bulb function.

I do not know how long this has been going on (doubt long). Last week I did do timing-belt job myself (thanks to Timmy the Toolman!) but that did not involve anything with wiring. I did reinforce the wire assembly on top of engine cuz flimsy plastic casing broke (as it does)…and I did unbolt the starter wire harness underneath to gain access to a bolt (and reinstalled afterwards)…but I “think” none of the rear light wiring is a part of any of that? So…I’m stumped.

Any thoughts?

2ToyGuy

Have you tried removing the tail light's entire bucket, the whole thing, and check the grounds behind it? They are known for developing corrosion, causing lots of problems. Pull the entire bucket containing the tail lights, and examine the grounds. Make sure they're clean and shiney. No corrosion, dirt build up, etc. Check the tail light socket to the ground points, too.

Also, measure the ground point the tail lights use all the way to the battery negative. No matter what, the ground points the tail lights use should read close to zero ohms all the way down to the battery negative. Any more than that can cause troubles.

Just a couple thoughts. I get so few any more...
Pat☺

JamesDINAN

Hi Pat…today I was finally able to get brake light working (and got insp passed). Not saying I fixed the prob but…I have the 3rd party “Factory” installed Gulf States alarm system. What temporarily fixed the problem is, all I had to do is toggle the On/Off switch underneath the dash. When it’s flipped one way, I get one brake light…when it’s flipped the other way, I get both brake lights. Feels like a ground issue. Think couple months ago I starting peeking underneath there cuz I bought a basic keyless entry system and was going to attempt install but, ran into probs anytime I started playing with Gulf States system. Want to remove the whole thing (and found what seems to be good post for doing-so) and just haven’t gotten around to it (was scared of f’ing sometihng up in the winter and having truck not start, etc). Anyway…small victory. Just wanted to give update.

2ToyGuy

OK, you think it's a ground problem. So far, so good!

Time to break out the trusty multimeter, set it to OHMs, and start checking grounds like I said. With the magic switch one way, and then the other. From the brake light bucket's ground, all the way to the battery negative.

A little trick us electronics techs use is when you find a problem, start splitting the system in half. Go halfway from where the problem is to the battery negative. Still have the problem? If so, go halfway the rest of the way. If not, go halfway back towards where the problem was. Every time you split the system, you're eliminating a lot of the system, thus making it speedier, and easier to find the trouble, you see? Make sure the battery terminals are both removed from the battery. Even a slight voltage into a multimeter measuring ohms can blow a fuse in the meter. It's a very sensitive part of the meter.

Good luck!
Pat☺