No brake lights

My son's 2006 Tundra is having a brake light problem. The high mount brake light works but the other 2 don't. The tail lights work so I'm assuming it can't be a ground issue since they are combo bulbs. The brake light switch must be good or else the high mount would not work. Anyone have a suggestion? Thank you.

 

IIRC, the high mount 3rd brake light is on a separate harness via the roof harness. So this is why it'd be OK. Weird the tail lights work, but the brake doesn't, unless...

Stupid question, but are dual-filament bulbs installed? If there's only one filament, then you're only going to get the tail lights with no brake lights.

Also, are the housings original? Or aftermarket?

Lastly, has anyone spliced into the wiring with garbage t-taps or scotchloks to add a trailer harness or anything?

 

All good questions. I will have to ask my son for the answers. Thank you for replying.

 

Aren't these on two separate circuits? I'd have to look but I feel that there is a "brake" fuse and also a "tail" fuse.

EDIT: Not my pic but the stop in the bottom right is the brake lamp fuse, correct?

 

It's also probably worth asking if he switch out the bulbs for LEDs. Most LEDs are polarized, i.e. there is a positive and negative side (unmarked), and they only work installed one way. If they're LEDs, he might try taking out the bulb, rotating 180°, and reinstalling. Or replace them with dual-filament halogens.

 

I'm not entirely sure how they come out of the integration relay (aka fusebox) in the dash. Maybe it's two wires outbound, one takes the chassis harness down the driver's side, the other goes up to the roof. But I'm fairly certain the TPMS, HMSL, dome light, sunroof, etc. are all on the roof harness coming up the A-pillar. I'm open to being wrong on this one, I've never directly had to dig into the wiring, but that's also the only logical way that makes sense to me, they're definitely not going to run the brake lights in series from the integration relay, up to the roof, down off the roof then back to the tail lights would be silly.

I'd be more inclined to believe we have a hardware situation. Either the brake light wire somehow got tapped into where it reaches the driver rear corner, or they used the wrong bulb (single filament), or they switched to LED.

 

The bulbs were changed during inspection so I don't know it the proper bulbs were used. I will have to check them out tomorrow. No wire splices or after market housings or led bulbs.

 

Check to confirm a dual-filament bulb was used. You should be able to see both filaments, two pairs of arms with suspended filament, it should be blatantly obvious. Dual-filament is traditionally required for any bulb that has a dim/high mode, on filament for basic light, the other for brighter light. I think all single fil bulbs have a single conductor on the bottom and dual have two conductors on the bottom but I may be wrong.

Top bulb here is dual filament. Bottom pair of bulbs here is single filament. It would be a simple "1d10t" mistake to use a single filament, but also a good lesson to learn. I'd be lying to you if I told you I didn't make the same mistake when I was a wee lad.

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Just to make sure it's not a ground problem, have him turn on the headlight and have someone watch when he applies the brakes. Look for a change in brilliance.

 

Ok I will try these suggestions tomorrow if it doesn't snow too hard. I appreciate the help.

 

I had one side out. Turns out the short harness from under the bed into the taillight well went bad.

 

Welcome to the forum..

Ultimate TUNDRA Wiring Diagrams Collection | Toyota Tundra Forum (tundras.com)

Just for reference..
Not sure if he has a standard, access, or double cab...
Good luck..

 

When mine stopped working it was the brake light switch. It would also cause my cruise light to randomly blink. I'm unsure if the 3rd brake light was still working or not.

 

Good call, forgot about the brake light switch, but if it was that, the HSML/3rd light wouldn't light up, and OP said that was lighting up.

 

Snowing today so I won't be working on it. Tomorrow it doesn't get out of the teens so that's a no go also. I'll report back when I figure it out. I'm guessing a bad connector or partial ground. Hopefully just the wrong bulbs but that would be too easy.

 

We all love "Too easy"!

 

In the access cab wiring diagram above(post #12), is the rectangular grey box shown located in the cab's kick panel?

 

Found the fault. It was corroded wires before the brake/tail light socket. This truck came with a factory trailer package. A crimp connector/heat shrink combo was used to tap the brake light wire on the passenger side. This is where the wire corroded. The driver side was out because of a burnt out bulb only. Thanks for the help guys.

 

Thanks for looping back! This is ultimately why I asked if anyone had spliced in the first reply. We usually hear about scotchlocks/t-taps causing stuff like this, I'm surprised to hear a butt splice or similar crimp did it. Too bad they didn't use a Posi-tap...

 

I assume it was a factory job, mostly because the heat shrink was heavy duty. Very thick. Not being the original owner I can't say for sure except to say it came through originally with the trailer package.