Trailer Turn Signals and Brake Lights Do Not Work Unless 2005 Honda CR-V is Running

Question:

I recently purchased and installed a Curt trailer hitch and wiring harness#55336 for my 2005 Honda CRV. When I connect the harness to the trailer wiring Trailex SUT-500, the running lights, turn signals and brake lights work properly as long as the CRV engine is running. When the engine is not running, but the ignition switch is in the on position, all the lights on the CRV work, but on the trailer only the running lights work. In other words, the brake and signal lights only work when the engine is actually running. The wiring seems to be OK no shorts or opens that I could find. Do you know what might cause this problem? Any ideas would be appreciated. Thanks.

asked by: Tim M

Expert Reply:

If you have not detected a short or a faulty ground then the likely issue is that the factory wiring that you plugged the harness into must have some feature that does not allow the harness to be fully functional if the motor is turned off.

Presumably though if the motor is off then you wouldn't be moving and the brake lights and turn signals do not have to work. But for testing purposes, that would be a little annoying.

You can test the 4-Way further by following the help article I have linked to the right. It would be interesting to see if the 4-Way has the same voltage with the motor running or not when the trailer is not connected. You would need a multimeter, # PT89ZR, to test for voltage.

expert reply by: Michael H