Troubleshooting Lights on Bike Rack on 2022 4Runner Towed by Motorhome Not Working

Question:

I tow a 2022 TRD Off Road 4Runner behind a new motorhome with LED tail lights. Could not fit bulbs in rear tail lights of 4Runner like I did 2 previous Tacomas I towed, so I mounted LED boat trailer lights on bike rack and ran stand alone wire to rear bumper from motorhome to avoid tying into vehicle wiring. Towed successfully for 8000 miles and 6 months hooking up and unhooking 12-15 times. On last trip, during light check found left turn signal at bike rack not working. Used vom to check all connections and verified connections and power from motorhome to pigtail to rear of toad. Plugged in and now left turn works but taillights do not on bike rack of toad. First thing I think is a ground problem. I am grounding thru harness back to motorhome only. Hear of people having to add resisters sometimes. Would this help?

asked by: Mike K

Expert Reply:

From what you are describing it sounds like you have a bad connector or a bad ground connection. Resistors are not going to solve the problem. I would double check the ground wire and also make sure that it is secure on a clean, bare metal surface.

If everything checks out with your ground connection, the issue may also be your trailer connector since it has jumped pins with the different lights not working. Since you checked your vehicle side connector the trailer end connector is probably the problem.

I'm not sure what testing you have done exactly, but I would test right behind the 4-way connection on the trailer side with a circuit tester like # PTW2993. If you aren't getting a signal on one or several of the wires then the connector is the issue and should be replaced with one like the # HM48133.

expert reply by: Robin H