Can A Trailer Wire Harness Drain The Battery If It Has A Bad Converter Box

Updated 09/03/2024 | Published 08/28/2024

Products Featured in This Question

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(96)

$68.94

Digital Multimeter with 42" Long Test Leads - LED Display

(3)

$22.17

Question:

I installed this wiring harness several years ago and have not used it for a while. I tested it recently and it was not working and I discovered that the wire to the battery was disconnected. I reconnected the wire and all was good for about 10 minutes at which time I tried to start the vehicle and the battery was dead. I removed the from the wire to the battery, charged the battery. Could the converter be damaged/defective and this is the cause of the battery drain? Thanks.

asked by: Richard

Expert Reply:

Hi Richard,

The Tekonsha # 118563 shouldn't be able to pull enough to drain your battery within 10 minutes unless it has a wire shorting to something else but you'd likely find something very hot or smell something burning. I definitely think you have a wiring issue but without actually looking I can't confirm that the wire harness is the culprit. I would doublecheck the wiring to see if anything is brittle, burned up, or nicked and that each wire is making a secure connection.

You can test the wires with a multimeter # PT89ZR before and after the converter to see if the converter is functioning properly and sending the correct signals through to the trailer. Have you installed any other things in your vehicle that could possibly draining the battery? I would also go to your local auto parts store and have them test your battery to see if you might just have a failing cell. I had one on my truck and the battery would stay charged and work once but then wouldn't have enough power to crank again.

If it's been more 5 or more years then your wire harness might just need to be replaced. Typically they just fail and stop sending light signals through but your converter box might just be pulling a bunch of power and heating up/shorting out. Have you tested it with a trailer yet to see if the light signals are functioning?

expert reply by: Kevin C

Richard

9/3/2024

Turns out the battery drained while I was working on the harness connection because I had the doors opened with the interior lights on for a while. The battery is not new so the drain was enough. Once the battery charged everything was good.

Kevin C.

9/3/2024

@Richard Good to hear. If you still want to check the convert box just poke into the wiring before and after the box with a tester # PTW2993 or multimeter # PT89ZR to see if signals are coming through correctly.