12 Volt Circuit On 1999 Dodge Ram 7-Way Trailer Connector Does Not Charge Break Away Battery

Published 07/24/2013

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Question:

Last year I purchased a Tekonsha Primus IQ brake controller for my 16foot trailer which has a Hopkins Engager. My 1999 Dodge Ram 1500 does not have a factory installed tow package, so I also purchased the wiring harness to connect to the plug underneath the dash. The installation was simple, but my problem is that the battery on the trailer does not charge. From what I have been reading on etrailer.com, it appears that I need an auxiliary power source? Thanks so much! Is there any additional information that you need to address this question?

asked by: Tim L

Helpful Expert Reply:

You can use a circuit tester like # PTW2993 to test the 12-volt circuit on the 7-Way to see if it is has power. If it is not and the 7-Way is factory it might just be a blown fuse to that circuit. Use the owner's manual to find the location of the tow package fuses to check them.

Or you can get about 20 feet of # 10-1-1 wire and attach one end to the back of the 7-Way in the 11:00 position. Route the other end under the truck, avoiding areas that may pinch or burn the wire, and up into the engine compartment near the battery.

Under the hood near the battery, you will need to mount a 40-amp circuit breaker, # PK54540, to the metal of the engine compartment. Attach the wire you ran to the circuit breaker and cut off the excess wire. Attach the wire to the AUX post of the circuit breaker. Then with the leftover wire attach one end to the BAT post and the other end to the positive battery terminal.

This will make the 12-volt circuit hot and will charge the breakaway battery. If your 12-volt circuit is hot and the battery still does not charge, then there is either an issue with how it is wired or with the charger part of the breakaway system. I have included some links on break away systems that should help.

expert reply by: Michael H