Troubleshooting No Brake Lights on Trailer with Tekonsha Harness for Volvo 2008 V70

Question:

I have a 2008 V70 Volvo. I got the Tekonsha Tow Ready custom wiring harness 118463 for a trailer. The running lights work and the blinkers work but the brake lights do not work. I know the trailer lights are good because they work with my truck. What could be the problem?

asked by: Al T

Expert Reply:

The brake lights and turn signals are sent along the same circuit for trailer wiring so it's a bit odd that the turn signals are working fine but the brake lights aren't powering on with the Tekonsha Harness # 118463 installed. Most likely the culprit is a bad or weak ground on the harness. Since brake lights require a more constant power draw when activated a weak ground might be allowing enough power for the turn signals but not enough to fully power the lights when the brakes are applied.

Make sure the ground wire for the Tekonsha harness is securely attached a to clean, bare metal surface that's free of any debris or corrosion. Even though the trailer worked okay with a different vehicle it won't hurt to also check the grounds for the individual light assemblies, whether they ground through a dedicated wire or through their mounting hardware.

If this doesn't resolve the issue please let me know and we can continue to troubleshoot.

expert reply by: Chris R