Should A Curt Trailer Wiring Harness Be Drawing Power With Nothing Attached?

Updated 08/11/2026 | Published 08/06/2026

Question:

C56261 Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector. Draws 4 amps with lights disconnected. Works properly otherwise. Whats going on?

asked by: john s

Expert Reply:

Hi John!

Drawing 4 amps with nothing connected is definitely odd. Whenever we hear something odd happening in regards to wiring, 9 times out of 10 it's a grounding issue. Make sure your ground is connected to a good bare metal spot (that isn't aluminum) and it isn't "stacked" with other ground sources. This is a fairly common practice and I always advise against it. Grounds should be grounded, not attached to other wiring. Even if it is another ground wire.

If that's good, you likely have a short somewhere and the harness will need to be replaced. I don't think this is super likely though. Typically with a short, other things won't be working properly and you mentioned it doing what it should be doing most of the time. I'm 99% sure it's just your ground.

What are you typically using the wiring harness for? Towing or a rack with lights?

expert reply by: Lazer S

John S.

8/10/2026

Towing a utility trailer Has new led lights. Works fine otherwise

Lazer S.

8/10/2026

@JohnS Gotcha. It might not hurt to check all the grounds for the new lights as well, but I still think it's the ground for the actual harness. Let me know how it goes! ^___^

Ian

8/11/2026

@JohnS Also check you positive wire to the battery. We had ours installed at U-Haul and the tech for some unknown reason routed our wire along moving parts. We found the fuse had blown, wire was broken in places and nearly wrapped around an axel. So check your wire for damage if it’s outside the vehicle.

Lazer S.

8/11/2026

@Ian Not a bad idea. Checking the power wire, I mean. Attaching a wire to a moving part is a very bad idea! Why they did something like that is pretty baffling.

See All (5) Replies to John S. ∨

Jim M.

8/11/2026

I am not an electrician so I followed the excellent directions exactly. Everything works fine for 2 + years . I never thought to see if there was a draw when unconnected, plus I wouldn't know how!

Lazer S.

8/11/2026

@JimM Haha! Most people don't have the know how or parts to test this kind of thing, so don't worry about it. And I think you would have noticed a dead battery if you were getting parasitic draw like John is getting, so everything sounds like it was installed properly and is working properly! ^___^