Recommended Wiring and Solution to Only Have 12V Power on 7-Way While Engine is Running

Question:

I am going to use a 38175 4 pin to 4 pin 7 pin adaptor to add a 7 pin connection to my 2018 chevy express van. I need to supply 12v to the camper I will be towing while it is towed. I would like the 12v supply pin in the 7 pin connector to only be hot when the engine is running. The van does not have factory installed towing wiring or fuse panel locations wired for towing. Are there any wiring diagrams or videos on your site that cover this situation? Any help you can provide would be appreciated.

asked by: Charles D

Expert Reply:

I will start by covering the basic wiring you will need to add the 7-way to your 2018 Chevy Express Van. Since you do not have any existing wiring you will want to start by adding a 4-way. The most reliable option is the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118392. Once this is done, you will be able to add the 7-way connection.

Instead of the # 37185 I recommend using the Universal Installation Kit # ETBC7. This kit comes with the adapter, wiring, and everything else you need to upgrade the 4-way to a 7-way.

In order to make sure the 12V power is only active when the engine is running you will need to use an isolator solenoid # PK5231201. You will have the power running in from the battery on one side with the power running out on the other. In the center you will need to connect the pin to a keyed/ignition switched power source so there will only be power when the engine is running.

You should note that this circuit can't charge a trailer battery very well. At best it can help maintain a charged trailer battery.

I have attached installation videos for the wiring harnesses, as well as a diagram for the solenoid. We don't have a specific wiring diagram or installation video for the solenoid since this is not common practice. If you're worried about draining the battery, you could also unplug the camper as an alternative.