Question:
When the Sprinter headlamps are on 12 Volts appears on the three signal wires of the trailer wiring harness. When the headlamps are off, the brake and turn signals operate properly. The 12 Volts on all the lines turns on all the lamps in the trailer lights simultaneously so no brake or signal is distinguishable. Thank you
asked by: Bill
Expert Reply:
It sounds like you may have an issue with the wiring for the Tekonsha ZCI Circuit Protected Vehicle Wiring Harness part # 119250KIT. There should not be 12 volts on the right turn/stop (green wire) and left turn/stop (yellow wire) at the trailer controller with the headlights on, only the running light circuit (brown wire).
I recommend you check the wires that you have the green, yellow, and red wires on the above harness connected to. If your Sprinter Van uses the same wire for both the turn and stop signals then the red wire will not be used. If if your Sprinter Van uses different wires for the turn and stop signals then the red wire will be used and attached to the stop light wire. If you use the circuit tester that is included with the kit and retest all of the wires you have spliced into on the vehicle then I believe you will find the issue. The ground if not securely attached to a bare metal surface could also cause issues as well.
ZCI Circuit Protected Vehicle Wiring Harness w/ 4-Pole Flat Trailer Connector and Installation Kit