Question about 12V charging while flat towing JL

[CoolTech]

Originally Posted by CWSWine

That is good to know since I don't tow at night and the harnesses were on sale for 56.00 bucks and no switch I have to remember to throw. I will check but I think you're wrong and my accessory plug stays on till the Jeep goes to sleep.

You may be confusing this with power accessory delay. This feature leaves power on to the radio, power windows, accessory power outlet, etc. after the key is turned to the OFF position. Power accessory delay is canceled when a door is opened. This is different than "sleep state".

[CoolTech]

Originally Posted by fcbbob15

I have been towing a 2020 JL with led lights and start/stop using the Mopar wiring harness. So far no issues. Now I will test and see if the lights wake up.

Yes, there have been many people with the Mopar harness chiming in on the Jeep forums with the battery drain issue.

We've devised an easy test to check to see if your Jeep is awake (and drawing current). Before exiting your Jeep, roll down the driver's side window, get out and shut the door. After 3-5 minutes, you can reach in through the open window and press the brake pedal with a broomstick handle. If the rear brake lights do not illuminate, the Jeep is asleep.

If you want to verify the problem that I have described, wait until the next time you have your Jeep connected to the motorhome. Connect it as you usually would. Once it is all connected, perform the broomstick test. The rear brake lights will not illuminate. Now, operate one of the turn signals in the coach (which will invoke the Jeep's turn signal). Right after you do this, repeat the broomstick test. The Jeep's brake lights will illuminate indicating that the Jeep is now awake.

[BVThunder]

Originally Posted by redbaron73

Unless you have installed the bypass on the fuse box, your front 12v is not going to remain active after the jeep sleeps. The bypass converts it from ignition source to battery source.

OP here... The easiest solution for this issue is to run a 12V extension cord from the 12V outlet in the rear cargo compartment to power the braking system. According to the owner's manual that outlet is wired directly to the battery. Ours is an Unlimited model. Not sure if the lower JL models have that outlet in the cargo compartment.

[RealNiceTent]

Originally Posted by Sbrownstein

The breakaway system will not function without power. You need the 12 volt battery in the circuit for this to happen.

Just like with trailer brakes a small 12volt motorcycle battery could be used to handle those duties. If you have a dead battery in the jeep the breakaway system will not work anyhow. A dead battery also would mean the brake system would not be working either, by powering the systems independent of the towed vehicle, theoretically you ensure the system always works as long as it is connected to the tow vehicle.

[Sbrownstein]

Originally Posted by RealNiceTent

Just like with trailer brakes a small 12volt motorcycle battery could be used to handle those duties. If you have a dead battery in the jeep the breakaway system will not work anyhow. A dead battery also would mean the brake system would not be working either, by powering the systems independent of the towed vehicle, theoretically you ensure the system always works as long as it is connected to the tow vehicle.

While that is true, a charge line from the coach solves all of that. On my Buick Enclave I don't even take the fuses out when towing. Without a charge line the electronics in the car will drain the battery down too far. While I have an Invisibrake I do not use their trickle charge wiring .