Hey All,

I installed the towing package using toyota\lexus parts a month or so ago and never got around testing it. This past weekend I rented a uhaul trailer and come to find that the tail lights and turn signals are working but the side marker lights don't turn on when I turn on the lights.

I have the OEM 7 pin connector and bought a toyota 7 pin to 4 pin connector. Does anybody know if I'm missing something or how I can go about testing it? Uhaul tested all of the fuses in the engine bay and under the driver side panel - didn't test any relays, but all fuses were fine.

If you have a wiring diagram for the towing harness I can use that.

Thanks,

Ken

 

The side marker lights are fed by the same brown wire on the 4 flat connector which feed the tail lights (usually pin 3). If the tail lights work and the marker lights don't, it's almost ALWAYS a trailer wiring problem. You can put a multimeter in your 3rd pin, measure voltage with brake down versus voltage with lights on. If you get voltage in both situations your wiring is fine. Only issue I've heard of causing side marker failure due to vehicle was improper wire gauge for brown wire (18 ga min) but if you are using OEM harness this should not be a problem.

On my 2004, I added non-factory towing package and side markers on all 3 trailer work without having to install any new fuses or relays. I do not believe you should need anything else... Uhaul has some real garbage sometimes as well.

 

Here you go Tow Lamp Circuit 1 & 2. Wiring Diagram.

 

You guys are awesome! Thanks for the info. I'll test my wiring out.

Thanks,

Ken