Trailer Lights Not Working with 2008 Toyota Sienna with Never Used Tow Package Wiring

Question:

I have a popup trailer and the lights work perfectly when hooked up to my 1997 F-150, but I am trying to pull it with my 2008 Toyota Sienna. I had a tow package installed years ago, but never used it. I am now trying to use it and when I hook it up, a couple of wrong things happen. Left turn signal=Left turn signal Right turn signal=No signal Brake=Fast left turn signal only Running Lights=Running Lights The same thing happens when I hook up to a boat trailer that I know has good wiring. Any suggestions?

asked by: Wes S

Helpful Expert Reply:

Since you have not used the trailer wiring harness on your 2008 Toyota Sienna until recently then there are a couple of likely things happening. First, the pins on the vehicle side connector could have corrosion in them even if the harness was stowed away the whole time. that can happen to untreated metal. Using a wire brush or screwdriver to clean out the metal contacts will help.

The other thing to look at is the ground connection. This is usually a white wire. It needs to be connected to a clean and corrosion free bare metal surface. No paint or coating of any kind between the ground and the metal surface.

If you continue to have trouble then I recommend replacing the harness with a new one because the converter box on the one you have now could be shorted out. Tow Ready harness # 118304 is a great option and what I would use if it were my van. I have included a link to a video showing an example installation for you.

expert reply by: Michael H