Factory installed RV tow Harness

[CoolTech]

@Gaffer - Yes Factory LED taillights

If you have the optional rear LED lights and you are using ANY tow harness - including the OEM tow harness, the Jeep will come out of low-power sleep-state whenever a rear light is activated. Once out of sleep-state, the Jeep will be drawing about 4-6amps of power.... until it goes back into sleep state.

"But I have the LED lights and I don't have a problem!" Yes, I suspect many(most) owners do not suffer battery depletion for one or more of the following reasons;

1. Activation of a rear light WILL cause the Jeep to exit sleep state and begin drawing power. However, after a minute or two, the Jeep will go back to sleep.... until the next light activation. In normal daytime usage when the running lights are not on, the Jeep will spend a lot more time asleep than it does awake and most likely, this "bug" will not bite you.

2. Many owners have also incorporated a battery charging system - I suppose mostly to offset the power used by a supplemental brake system. These battery chargers will offset the current draw from the Jeep being awake and therefore, the battery drain does not occur.

If you have the rear LED lights and you do not have a charging system for the Jeep's battery AND you tow at night with the Jeep's lights activated.... you will most assuredly experience a depleted battery if your tow is 4+ hours or more.

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[sstuner]

@CoolTech I agree 100%, you will need to add a charging system to the battery with the Hopkins kit as I did.

 

[jjvincent]

I have a 2021 Jeep with the factory LED's. I bought the harness from Curt. It was plug and play. It also has an extra plug if you want to tow something behind the Jeep.

So far, I have towed that thing across the country more than once. Never a dead battery. This is towing it for 12 hours. Stopping, towing for another 12 hours. Unhook Jeep and it starts right up. I do not have an extra 12V wire running from the RV to the Jeep. I also run my headlights all of the time on the RV.

So I can tell you at least the Curt one does not deplete the battery in 4+ hours in a 2021 2dr Jeep with factory LED's. Maybe it does on other models or configurations.

 

[CoolTech]

@CoolTech I agree 100%, you will need to add a charging system to the battery with the Hopkins kit as I did.

Great! Do you have an aux braking system that moves the Jeep's brake pedal?

 

[CoolTech]

So I can tell you at least the Curt one does not deplete the battery in 4+ hours in a 2021 2dr Jeep with factory LED's. Maybe it does on other models or configurations.

That's really curious, John. Obviously I don't think you're making this up! Are you certain you have the REAR LED lights? On some configurations, its possible to have front LED headlights but not have the rear LED Lights.

The "issue" is that the LED rear lights sit on a circuit board. There's a fault-sense wire on this circuit board whose job it is to tell the Body Control Module (BCM) that the LED light is working when it is commanded on (12v applied). This fault-sense wire is only present on Jeeps with the rear LED lights. The issue is that this signal back to the BCM causes the Jeep to wake-up. It's curious why yours is not causing the Jeep to wake up.... maybe because 2-door or some other configuration combination?

 

[N8TVTXN]

As in everything else, there are different products at different price points. Do not assume everything is the same.

Will your harness work with the 2023s? I see it says 2018+ so assuming so. We currently flat tow our TJ behind our truck & slide-in camper and would plan to do the same with the new JL.

 

[Gaffer]

Here is an install video. It is on a JK but the process is the same. Different part number. Go to 10:24 on the video to see how the turn signal on the Jeep does not work from the motorhome when the Jeep brake pedal is pushed. Is this unique to LED lights or do you need a brake relay?

 

[jmait769]

I have the Mopar tow harness on my JLUR with LED rear lights and have no issues with turn signals or battery depletion. Functions as designed.

 

[CoolTech]

Go to 10:24 on the video to see how the turn signal on the Jeep does not work from the motorhome when the Jeep brake pedal is pushed. Is this unique to LED lights or do you need a brake relay?

This is really a demonstration of the problem for JL Jeeps with the rear LED lights.

Anyone can try this to get their arms around how the Jeep is working;

Start the Jeep and roll down the driver's side window. Now, turn the Jeep off, exit, and close the door. Wait 2-3 minutes. Now, stick a broom handle (or similar) in through the driver's window and depress the brake pedal. The left and right rear brake lights will NOT illuminate. This is one way to see/verify that the Jeep is ASLEEP. If you open the driver's door, sit down in the seat and press the brake pedal, the left and right rear brake lights WILL illuminate. Opening the driver's door woke the Jeep up.

So, theoretically, when towing a Jeep JL the Jeep's brake lights should not interfere with the turn signal command coming from the tow vehicle. All is good - as long as the Jeep stays asleep. But, in an event where the Jeep wakes up, the "conflict" shown in the video ~10:24 mark will occur.

 

[CoolTech]

I have the Mopar tow harness on my JLUR with LED rear lights and have no issues with turn signals or battery depletion. Functions as designed.

What aux braking system are you using?

 

[JeepinJason33]

Regardless of which wiring setup you are using for your lights, I am amazed that you can flat tow with a braking system and not deplete the batteries. Maybe you are using one of systems that hooks up to the air brakes on your RV and does not need power. I use the RVi system and had to add in a battery minder system to keep the battery from running down. It was a one wire add on to the 6 wire plug and really easy to install.

 

[jmait769]

What aux braking system are you using?

https://www.jlwranglerforums.com/fo...g-when-flat-towing.15523/page-16#post-2006944

 

[sstuner]

Great! Do you have an aux braking system that moves the Jeep's brake pedal?

Yes, I have Roadmasters Brakemaster's unit which is plumbed to my air source in RV.

 

[Gaffer]

My question is. The problem shown on the video, does this only happen with LED tail lights?

 

[CoolTech]

My question is. The problem shown on the video, does this only happen with LED tail lights?

In short, yes. Your JL will go to sleep and the brake lights will NOT function in the Jeep so they will NOT conflict with a turn signal command from the tow vehicle.

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