How to Fix Backfeed From Trailer Battery and Solar Controller on 2024 GMC Sierra 2500

Published 10/24/2023

Products Featured in This Question

Roadmaster Hy-Power Diode - (Qty 1)

(366)

$18.99

Seaflo Battery Disconnect Switch for Boats and RVs - On/Off - 900 Amps

(72)

$19.94

Question:

I have a 2024 GMC Sierra and a fifth wheel with solar and controller. The Brake controller is throwing messages to my dash DIC saying the trailer brakes are connected and disconnected. GM put out a message saying the solar is charging the battery to say 14v and sending it back to the truck and causing the brake controller to wig out because the volts coming back are higher than the trucks voltage. If I install this diode Part RM-790, at the trucks 12V+ hot going to the trailer, will this stop the issue by not allowing the higher voltage coming back from the trailer? How would I wire it with the two spades on the one side? Or should I wire the diode at the trailers battery? Thanks

asked by: Anthony S

Expert Reply:

Installation of the # RM-790 will take care of that problem you're having. I would wire it on the trailer side at the battery rather than mess with the wiring on your 2024 Sierra 2500. The other solution is to follow the GM note and add a disconnect between the battery and solar controller like other trailer manufacturers have started to do. If you want to go that route you can use the # SE29VR.

expert reply by: Robin H