Can Hopkins 4-Way to 7-Way Adapter Drain Vehicle Battery

Question:

I just got my vehicle back from the shop and ordered part number 37185 to add the 7 pin and 4 pin functionality to the existing 4 pin. I don’t have brakes on the trailer that requires 7 pin so I just tucked the wires up and out of the way for future use. My question is, is there any reason my battery on the pathfinder would have died from this? I’m troubleshooting and didn’t know if it was the shop, the 37185 part, or maybe just a bad terminal connection? Basically, is there any parasitic draw if the truck is off with the 37185? No battery or brakes on the trailer. Thanks for any insight.

asked by: Sean B

Expert Reply:

I really can't think of any reason why hooking up the Hopkins 4-Pole to 7-Pole Adapter # 37185 would drain your vehicle's battery assuming everything is connected properly. It's much more likely that it was just a coincidence and the battery on your Pathfinder dying was unrelated to the adapter.

You mentioned not using/needing the blue brake output wire and tucking it out of the way (which is perfectly fine) but did you run the black 12V wire up to the Pathfinder's battery? If this wire isn't ran either then the adapter itself has no connection to the battery so there wouldn't be a way for it to draw power from it.

Otherwise if you did run this 12V wire then it still won't actually draw any power unless something is hooked up to the 7-Way (such as your trailer or other 12V accessory).

If your original 4-Way harness to which this adapter plugged in uses a powered converter then you might want to test the pins on the 4-Way to make sure they aren't getting constant power. It's technically possible that there could be something going on with the converter (if present) that's causing it to draw power from the battery at all times such as an internal short.

If you continue to have this issue please let me know and I will be happy to look into this further.

expert reply by: Chris R