Trailer Wiring Harness Issue - SOLVED!

Need help from any wiring gurus out there!

I replaced the trailer plug receptacle on my 2007 SR5 4x4 DCLB with the factory Honda one, which is an identical part, but with a different connector on the harness end.

I bashed mine on a rock within 6 months of getting my truck and it's been zip-tied to the bumper ever since.

Everything works good. But my R Turn/Stop on my trailer is always on.

I'm using a 7pin to 4 pin converter, that works good on my dad's factory F-150.

Tested the wires and I'm getting solid power from the Brown Wire (R Turn/Stop) when it should be flashing when the Right Blinker in turned on like the Red Wire (L Turn/Stop) is when the Left Blinker is turned on.

Also tested back at the connector and I'm getting solid power from the R Turn/Stop wire.

Which tells me its not the new plug receptacle or any part of the wire from it.

Any suggestions? Separate flasher relay for the blinker on the trailer but not on the regular lights? Replace the whole harness?

Any insight would be appreciated!

 

This can get interesting . Toyota`s are not wired like Fords

On our Toyota`s the brake and turn signal are separate I am guessing your Truck has a converter box if it does not you need one or it is giving you problems like so many do.

Your hardwired to the 7 pin plug on the truck then going to a 4 pin plug to the trailer or going the other way 4 pin to 7 pin for the trailer ?

Electrical issues are so much easier in person .

 

The wire in question originates from the towing converter relay, bottom right for the right turn signal. Perhaps that relay has an issue, it's up on the drivers side kick panel. I'd check there and see if you're getting a constant input from the turn signal flasher from the right turn

 

Brown is running lights.

Green is right/stop

Yellow is left/ stop.

Are you sure you have not " mirrored" the schematic? I've done it lots of times...and I build trailers so I should know better.

 

On the trailer that is the standard convention, the colors OP is speaking of are at the Toyota portion of the 7 pin harness, brown is right turn/stop, red is left turn/stop, yellow is backup, blue is brakes, green is running lights, black is charging, white is ground.

 

This.

 

Make sure you’ve got a good ground. Bad ground causes the weirdest issues

 

Thanks man, i am going to check that today, is there a good way to test to see if its causing constant power to the right turn signal? or just remove and replace and see if that works?

Thanks again for the pics

 

Yeah I took a picture of the back of the stock plug, and then replaced the plug in the same way i took it apart. I had another person check my work. The colors of the wires on that run the length of the truck are different colors then the back of the receptacle plug

 

not sure to be honest. What I would do is check to see if the input from the flasher (pin 3) and output (pin 2) have constant voltage. If the input doesn’t and the output does, it would make sense the towing converter relay is your issue. Unplug it and see if that fixes your issue. Not sure what’s internal to that relay from the drawing it looks like a microchip and two FETs

 

Seems to me if you switch those wires that are at the 11 o'clock and 1 o'clock position, you problems would be gone.

 

Let me try that, i did try switching the brown and black wires, but that didn't work. It does seem like the running lights are very bright.

 

PROBLEM SOLVED! It was the trailer converter relay.

 

They cause problems so often it is the first thing after the plug I check .

 

That seems crazy to me. I feel like they would last forever, its just a computer chip surrounded by a plastic case, hidden behind the kick panel. The thing looked brand new!

 

You have to remember people are in business to make money, everything is built to fail eventually. And these new style relays have more sensitive electronics than the old telephone style ones that lasted a lifetime. A few electrical surges is all it takes to cook one.

 

Yeah that makes more sense. Hopefully I'm not replacing this thing all the time, knock on wood. I was pretty happy when I tested it today and everything worked.

Ended up costing me 60 bucks for the new trailer receptacle and 40 bucks for the new relay. But hey... I'm towing now and I'm not the guy going down the road with no right blinker lol.