Troubleshooting No 12V Power Going to Trailer Break Away Battery

Updated 05/18/2018 | Published 05/17/2018

Question:

Hello experts, the UPG 42914 on our trailer is not charging. The orange light does not come on and there is not 12v coming to the box. GMC Sierrra 2500, 2013 with 7pin flat plug. All other lights working. No fuses blown on truck or trailer. thanks

asked by: STEVEN A

Helpful Expert Reply:

If the break away battery on your trailer is not charging and you aren't getting any 12V power on the wire leading to it, then I recommend starting by testing the 7-Way connector on your Sierra. You can use a circuit tester like # PTW2993 to ensure you are getting power at the connector on the 12V pin (1 o'clock position).

If you are getting power there, then there is an issue somewhere on the trailer side. You will want to inspect the trailer side connector for any debris or corrosion built up behind the pins, cleaning as needed. Then inspect the wiring going back from the 7-Way along the trailer, looking for any damaged or exposed wire.

If you do not get power at the truck side connector, then there is an issue on the Sierra side. The most likely culprit is a blown or missing fuse. You did mention that they seemed to be fine on your truck, but I recommend verifying this once more. According to the online owner's manual for your 2013 Sierra, there should be a 40A fuse located in the # 68 position inside the engine compartment fuse block. This particular fuse is needed for 12V trailer battery power.

If you still are not able to resolve the issue, please let me know and I will be happy to help you further.

expert reply by: Chris R