Trailer Turn Signals are Only Working Intermittently on Trailer Towed by 2001 Toyota Sienna

Question:

I Installed a #C55418 T-Connector Wiring Kit in my 2001 Toyota Sienna CE van. It almost works. The running lights, parking lights, turn signals and brake lights on the Van work ok. The trailer is tested unhitched from the van. On the trailer, the running lights, parking lights and brake lights work ok. The turn signals are, however, intermittent. Occasionally the R signal works for a while, and occasionally the L signal works for a while, but never consecutively or at the same time. A while is a couple of minutes, or 5- 6, R-L cycles. Occasionally neither signal will work. All the while the Van lights are working as they should. An LED tester shows everything working ok all the time on the van side of the connector. If I connect 12v bulbs directly to the Wiring Kit Connector, one or the other turn signal works intermittently, the same as described for the trailer lights. With some playing around suddenly one or the other turn signal begins to work for no apparent reason. ? any explanation?

asked by: Paul B

Expert Reply:

Ground problems can cause all sorts of weird things to happen. Most likely that is the problem. Since you tested the 4-Way on the van and it is working that narrows down the issue to the trailer.

First make sure that the trailer connector is free of dirt and corrosion. This can cause a bad ground and if you are moving things around and it suddenly starts to work it could be because at a slightly different angle there is a better ground connection. OR there is a loose or broken connection you will need to track down.

Make sure the main trailer connector ground is attached to a clean and corrosion free bare metal surface. Do the same for each of the trailer lights. If the trailer has an aluminum frame, tilt bed, or folding tongue then you would want to run jumper ground wires from the lights to the main trailer connector ground.

expert reply by: Michael H