How to Allow 12 Volt Accessory Circuit of Trailer Wiring to Only Activate When Key is On

Question:

I am installing a Hopkins 4-Pole to 7-Pole and 4-Pole Adapter item # 37185 on a 2002 Toyota Tundra. I understand how to connect the black wire directly to the vehicle battery through a 40 amp circuit breaker so the adapter can charge the trailer battery. Can that connection be tied into the vehicle ignition circuit, so it only charges when the ignition is on? What is the best way to do that?

asked by: Mark U

Helpful Expert Reply:

To allow the 12 volt accessory circuit to only be active when key is on you'd have to use an isolation solenoid like the # PK5231201. You'd run this inline with the 12 volt accessory circuit on the outer posts and then run a keyed power source to the center pin to allow the circuit to complete. This would allow you to have the circuit active only when the vehicle is on.

expert reply by: Jameson C