2001 Tacoma 3rd brake light not working.

2001 Tacoma, 2.7 liter, extended cab, 4X4
3rd, (upper) brake light has been intermittent since I bought the truck a few years ago. Today it won't come on at all. Bulbs are good. Tail brake lights are good.
I suspect a short somewhere because I'm getting battery voltage at both terminals at each lamp socket. I also read low resistance to ground on both terminals. The 10A Stop fuse is not blowing. Any ideas on where to look for the short? Seems odd that the fuse isn't blowing if there's a short somewhere.

Just realized I'm probably reading through the other bulbs, I'm going to go back out and check voltage and ground again with all three bulbs out.

 

Just something to help you out in case you fix it and it goes out again. This is what I did. It saves you from having to remove the headliner and all the panels. Done it on both my trucks.

 

Thanks for the tip.

I checked for ground and power at the light sockets with the bulbs removed. I get battery voltage at the top contacts with the brake pedal depressed. With brake pedal released, I get low resistance to ground at the top contacts and no continuity to ground at the bottom contacts.

So, I think there's a bad ground somewhere. Does anyone know where the grounds for the upper brake light are located?

 

PM’ed you with some relevant info. I would consider grounding the 3rd brake light near the light itself rather than chasing the ground all the way back through the back of dash fuse panel.

 

Thanks for the info. I've looked at the wiring diagrams and legends and can see the general locations of the wiring, connectors and grounds but the illustrations aren't detailed enough to be able to identify the exact location. There's a ground right above the driver's side kick panel but the wires are brown, not W-B like indicated on the wiring diagram.

I like the idea of grounding the 3rd brake light near the light but I don't like the idea of pulling the headliner to get at the wiring. I've considered drilling out the bolt heads that secure the light to the body but I don't know if the connector for the light will be accessible. I don't want to destroy the light trying to get it out.

There's two grounds indicated on the wiring diagram. I'm going to take another look today and see if I can find them.

 

I think you’re on the right track. The ground wire goes down the A pillar, you kinda have to stand on your head but you should be able to see it where it comes out of the plastic sleeve up under the dash.

 

I found the ground point on the left side above the kick panel. I also found the connector IG1 coming from the A pillar. There were some non-factory connections at IG1 but the wires checked good from the power side of the connector. Black wire is for the dome light.

I was able to get the headliner down enough to get at the 3rd brake light wires. The headliner got creased a little but it's not bad. I could probably have removed the light assembly but I was worried I'd have trouble getting the nuts back on and that I'd have to mess with whatever sealant might be under it. I could get on the nuts with a deep 10mm socket, there's a long post on the bolt.

I verified the ground wire between 1A (connects to back of fuse panel) and the 3rd brake light was open. I spliced in a ground wire, drilled a hole for a screw, removed paint and screwed down the new wire. Light is working now!

 

Outstanding!