Troubleshooting Trailer Battery Backfeed on 7-Way Auxiliary Circuit

Updated 10/02/2024 | Published 09/24/2024

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Question:

I just finished installing the 7pin cable with the leds. The led for the auxiliary circuit is on all the time even when not plugged into the tow vehicle. So obviously the circuit is energized by the house batteries. Any ideas?

asked by: Ron

Expert Reply:

Hi Ron; since the light remains on when you're not hooked up to the 7-way on your vehicle it indicates that a power backfeed from your house batteries like you said. This happens sometimes depending on how things are wired. The easiest solution is to add in a diode # RM-690 which will keep the power from running to the connector and powering the LED.

expert reply by: Robin H

Ron

9/26/2024

On what wire will I need to add the LED?

Robin H.

9/26/2024

@Ron black is the auxiliary power wire on the # HM20087 so you want to install the diode on the black wire.

Ron

9/26/2024

@RobinH I actually have 2 black wires. 1 coming from the tow vehicle via the 7 pin cable and a 14 gauge wire coming from the trailer that is connected to the blue wires from the rv and from the 7 pin cable. I suspect it needs to be installed on the 14 gauge wire before the blue wire connection. Your thoughts?

Robin H.

9/27/2024

@Ron it needs to be on the trailer side between the trailer connector and the battery on the auxiliary circuit since that is the one getting constant power.