4-Way Trailer Connector on a 2008 Toyota Highlander has Power with Vehicle Off

Question:

I installed a 4 flat trailer plug on my toyota highlander. When I plug the flat tester into the plug, all three lights light up with the car and ignition off. The turn signals, brakes, and tail lights all test out properly when car is turned on. Its a little un- nerving that the plug is energized when the car is off. Is this normal??

asked by: Maury S

Expert Reply:

The wiring harnesses for the 2008 Toyota Highlander all have power that goes to the converter box so it is possible that the pins could have some power to them all the time. The power may be enough to light the test lamp but is probably not enough to power on the trailer lights. You can confirm this by plugging in a trailer. Curt wiring harnesses have been known to do this but I have not heard of this issue on other brands.

You will also need to make sure that if your harness requires a separate ground that it is connected to a clean and corrosion free bare metal surface. Also check the harness wiring for any nicks that may have exposed wires touching metal.

expert reply by: Michael H

John

4/13/2013

Installed a 56034 today and had the same problem as Maury. Read 12 volts with lights and ignition off. When I hook it up to my trailer, the right tail light has three LED bulb glow real dim. Should I try a different brand than Curt?

Patrick B.

4/24/2013

That happens only because it takes so little current to make an LED glow. If you had incandescent lights on your trailer, they probably would not even dimly light.