Trailer Brake lights not working?!?

Iv got an 06 Taco SR5, Bought the truck last year used. Never towed anything behind it till last month. The brake lights wouldn't work but everything else does. The trailer is a 4 pin.

Everything works like usual except the brake lights don't work. I can't figure out the problem. The running lights come on, and all the signals work, but when I push the brakes, the trailer lights don't light up. My dad has wired F18's and he has no clue wtf is going on?!? LoL. He's convinced I need to buy this wiring harness from etrailer in order for it to work.

http://www.etrailer.com/Custom-Fit-Vehicle-Wiring/Toyota/Tacoma/2006/118496.html?vehicleid=20066955

**Note** The trailer lights work fine on his 2010 F150.

HELP?!?

 

im having the ssame problem.. just bought my 2012 sr5 with the tow package... hooked up my trailer 5 min. ago, and nothing but running lights. need to tow in an hour... gotta figure it out.

 

Trailer wires, bad lights, something wrong with your plug or wiring...is there another truck you can hook it up to check if the problem is the trailer or the truck??

 

If the trailer turn signals work and the brake lights do not, the problem is most likely in the converter box that is part of the harness you linked. The turn signals and the brake lights use the same bulbs and wires in the trailer harness.

 

i checked voltage at the plug , and the adapter .. all is good. i lost voltage on my left turn/ brake, and replaced the light its self (had a spare) so i'm guessing i have a bad wire somewhere in the trailer its self.

 

This ^^^

I had my hoppy converter harness go bad last year. After checking the voltage coming in to the converter and out, it turns out the converter was bad.

 

That happened to me on my old Mazda B2200 - the converter crapped out.

 

My running lights didn't work on the trailer because of a blown fuse up front.... Not sure if the brakes have one too...

 

The factory brake relay is a much better choice than aftermarket trailer wiring. The critical components are kept protected inside the cab with just a wire running to the bumper, it also feeds the trailer off a separate circuit so it doesn't interfere with the truck tail lights.

If all the lights on the trailer work except for the brake lights, i.e. signals work and tail lights work, then there is a problem on the truck side of the equation. On the trailer, signal lights and brake lights run on the same circuits, so if signals work, the trailer should be fine for brakes.

Have a look at what the truck side trailer wiring runs into. I would guess a bad aftermarket converter box, or previous owner wired straight into the tail/signal lights and didn't even wire up the brakes. Some people do really stupid things when the situation gets slightly more complicated than their brains are capable of processing. The truck uses separate tail, signal, and brake bulbs. The signal and brakes need to be joined together in order to feed the trailer, but in a way where they can't cross power the opposing circuit on the truck.

Now the existing wiring on the truck is one of three possibilities;
1) trailer plug is wired straight in to signal/tail on the truck (very bad).
2) truck has aftermarket "T" connector plugged in behind the bumper and/or tail lights (better).
3) trailer light wire runs along the frame and into the cab under the driver's seat, and up into the driver's kick panel to a converter box (best).

I believe that it is unlikely to be (3) in this case. If it is (2), the converter box is shot and it would be a great time to head over to the dealer and upgrade to (3).

If the existing wiring is (3), then its probably just a bad fuse or relay in the fuse block under the hood behind the battery.