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Troubleshooint no Aux Power on the 7-Way Connector on 2016 Mercedes-Benz GLE350D


I have no aux power on the 7 pin connector. Ani idea on how to activate? 2016 Mercedes-Benz GLE350D


Expert Reply:

On the 7 Way Trailer Connector Vehicle Tester # TR20117 you asked from the function code for the aux power that is listed on other testers is the BU label for back up or reverse circuit. This will test the center pole of your 7-way that can alternatively be used for an auxiliary power on certain applications. If your vehicle is wired for the AUX as reverse, then you will need to shift the transmission into reverse to check that feature on the tester.

If you are having problems with that feature not working when it the function should be active, then you will need to trace your vehicle wiring to see if there is any damage, a fuse or relay associated or even a circuit breaker. There are 2 fuse boxes, one under the hood and another under the rear bench seat.

If you instead wanted 12V power to charge your trailer battery, you will check fuses and relays for anything compatible (your owners manual doesn't give a diagram for me to assist) and then if you determine you need to bypass the system, you can add that line using # 10-1-1 wire and circuit breaker # 9510. This will connect to your positive battery terminal and then to the 1 o'clock pin location on your 7-way.

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