Parts Needed to Have 12V Trailer Battery Charging Circuit on 7-Way Connector

Question:

I am going to buy a tekonsha p3 brake controller. quick question about installing. I am using a 2014 chev express with factory tow package. have located wiring under dash. will be pulling a dump trailer that has a battery on board. one of the pins on the 7 way is supposed to charge the battery. is that part of the 4 wire harness install? or does that charging wire need to be run additionally?

asked by: Phil R

Expert Reply:

The charging circuit on a vehicle 7-way style connector, the one that would deliver a maintenance charge to the trailer battery while you tow, is completely separate from the 4-wire brake controller wiring. This trailer charging circuit is usually carried on the contact at the 1-o-clock position as you look at your van's 7-way socket (please see photo). Note this circuit deliver a maintenance-level charge to keep a charged battery topped off, but it does NOT deliver enough juice to charge a battery that has been depleted. An AC-powered charger like # CTEK56353 is required to charge a depleted battery.

This charging circuit is delivered on a 10-gauge wire like # 10-1-1 that runs through a 40-amp circuit breaker like # PK54540 to your battery's positive terminal.

A brake controller wiring harness that you would use to install a Prodigy P3 # 90195 in your Express van DOES carry 12V power to operate the brake controller (this is carried on the black wire) but this is separate from the trailer charging circuit.

If your van has only a 4-pole flat type connector like # 118392 you can convert that to a 7-way with the trailer charging circuit by using our kit # ETBC7. This kit includes every part you need.