How To Solve A Dead Battery Issue When Flat Towing A Jeep Wrangler

Question:

I installed the BLU79FR in my new 2021 Wrangler Unlimited Rubicon about two years ago and it has worked flawlessly. However, sometimes when towed for 10-12 hours the battery would lose charge. Lately even on short one hour trips the battery loses enough charge that it needs to be jumped to start after flat towing. Could the BLU79FR harness be causing this issue?

asked by: Doug S

Expert Reply:

The Blue Ox Tow Bar Wiring Kit # BLU79FR shouldn't be pulling enough to drain your Wrangler's battery in a short amount of time so you most likely have something else that's draining the battery. That being said, you can easily fix this issue by installing a charge line kit like the Roadmaster Battery Charge Line Kit for Towed Vehicles # RM-156-25.

Since the wire harness you used is only a 4-pole you would need to cut the connector off and wire it into a 6-pole socket like you'd get with the Roadmaster 7-Wire to 6-Wire Flexo-Coil Kit # RM-146-7. This is also going to include a 7 to 6 wire cable so that you can transfer your signals as well as the charge line from the motorhome. If your motorhome doesn't have a charge line ran to the 7-way then you will also need part # RM-156-75.

This setup will keep your Wrangler's battery charged while you tow so that you never have to worry about jumping the battery when you reach your destination.

expert reply by: Kevin C