Tail lights, 3rd Brake Light stay on when everything is switched off

[xxcanuckxx]

2007 3 door Yaris Hatchback RS Manual Transmission
Braking still makes the lights significantly brighter, so I am safe driving.
Played with the brake pedal switch, disconnected it, doesn't solve problem.
Removing blue "15" fuse (in engine bay fuse box), turns the lights off and also makes the remote lock stop working. I am pulling the fuse out when I park, but not an ideal long term solution!
Please Help! I am not ready for a new car yet!

[TiedBassDrummer]

I'm no where near an expert when it comes to electrical problems, but that sounds like the brake light has a short to ground? From lurking in plenty of automotive repair forums, that seem like a go-to first check in this kind of situation.

[xxcanuckxx]

That's what I am thinking... I seem to remember some water collecting in the spare tire well in years past. I haven't opened my trunk in ages, I am wondering if there is a puddle in there somewhere...
I might be fooling myself, but I think it only happens on wet days, and warmer weather. This cold snap seems to have eliminated the problem... I probably have a less conductive block of ice in there right now...

[myfirstyota]

The only thing that comes to mind is that there's no wires down there for a puddle of water to affect. The only wires that go that low into the trunk pan is for the licence plate light. The rest of the wires for the tail lights, defroster and whatnot are routed over the wheel well and up the C pillar. I'd maybe check under the drivers door sill. 2 of the yaris I've had have had rust there. Maybe some corrosion? Or possible pinch point? For the 10 seconds it takes to remove it, worth taking a poke around.

There's also a ground location above both wheel wells. 10mm bolt. Possible loose ground? I'd pull the back panels off and take a look at everything. But be careful. Don't pull off the panels in the cold. You will break clips.

[tmontague]

for a proper diagnosis grab a repair manual and take a look at the electrical wiring diagram (EWD) for that circuit. It is likely a short to ground as stated above, probably a pinched wire. The colder it gets the stiffer the wires become and less plyable they are to bend and make contact with the frame.

The other cheaper option is to just remove the 3rd brake light completely. It is not illegal (in Ontario at least) to only have 2 working brake lights, nor is it unsafe as long as your others work properly. It is however a requirement for cars rolled off the assembly line to have 3 brake lights.

[Jwburgess]

My problem is the opposite of this. My brake lights stay on only when the engine is running. I have checked the wiring and the brake switch.2007 Yaris Hatchback