JLUR battery flatlining when flat towing

[lukemanke]

I find your posts to be very constructive and helpful.

In your tests that you just described in your previous post, the Jeep is staying in sleep-mode which is good and everything will work normally. You haven't yet done anything that would wake-up the Jeep.

Next time you are connected to your Jeep (and bored out of your mind, lol) leave the Jeep's window down and do the broomstick test after 5 minutes. The rear left and right brake lights will not illuminate... just as you described.

But, now turn on the running lights in the MH - which will cause the running lights of the Jeep to come on. I'm saying that by doing this the Jeep will wake-up. If you do the broomstick test now, the Jeep WILL light up its brake lights because it is awake.

@CoolTech- Thank you for all the information you've shared on this thread. I have a 2020 JLUR and had the 12V wire added from our RV, but am still getting the dead battery after longer towing days. Based on reading your posts it is due to the fact that the 12V is insufficient when the Jeep is constantly coming out of sleep mode? If that is the case I hope you don't mind two follow up questions:
1. Do you mind pointing me to the product you recommend we buy to help with this battery issue?
2. Does this wake and sleep mode still apply when you are using a M&G Airbreak system (we are in a diesel pusher)? I just want to make sure we get the right product so I can stop having to jump the jeep!

Thank you in advance!

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[GO_RV]

I installed this.
I towed my Jeep 4 down about 10,000 miles since February no battery problem
Charge line

 

[Twbrow]

I installed this.
I towed my Jeep 4 down about 10,000 miles since February no battery problem
Charge line

Did you run it from the 7 pin plug on the rv?

 

[GO_RV]

Did you run it from the 7 pin plug on the rv?

Yes.

 

[GO_RV]

Watch the video on this webpage.
they have an install video on the bottom of the page
Install video on the bottom of the page
also here is a newer install video
Another install video on the bottom of the page

 

[CoolTech]

Many good questions here and many owners have provided feedback that enables the collective "us" to know more about this problem. Just to be clear, we are only speaking about JL Wranglers and Gladiators with the REAR LED lights.

Based on the feedback/experience that we have witnessed, I'd say that the majority of owners may never know this problem exists. This is because the Jeep WILL exit sleep state whenever a rear light is activated by ANY towing harness, but after a couple of minutes the Jeep will go back into sleep state. As such, typical towing scenarios and durations would not necessarily cause the battery to drain because the Jeep simply isn't awake (drawing current) enough to pull down the battery.

The scenario that WILL bite you fast is towing at night... or towing with a coach that always has the headlights on (many of our Canadian friends as well as several higher-end coaches in the US). This is because the towing harness used will keep constant power to the rear marker lights... and the Jeep will stay awake. This is predominately why we see some owners say, "I have towing harness brand xyz and I've never had a problem" and others will say, "I installed towing harness brand abc and my Jeep battery dies." It is NOT one brand over the other - it is really the difference because one owner tows at night and another does not (or at least not for long durations).

But, perhaps the biggest reason the people never experience this problem is because the majority of owners have installed some type of charging system for the Jeep battery while being towed. This is a good (and fortunately popular) idea because a lot of the aux braking systems will consume local Jeep battery power for their operation. These battery charging systems will typically offset the current draw from the Jeep being out of sleep-state and the dead-battery problem never occurs.

In summary, I would postulate the following; (For JL Jeeps with the optional rear LED lights)

1. ALL Jeep towing wiring harnesses (even Mopar's) will cause the Jeep to exit sleep state when a rear (brake, turn, or marker) light is activated.

2. Typical day-time (lights off) driving scenarios are not sufficient to cause the Jeep's battery to drain as the Jeep will go back to sleep a couple of minutes after the light activation.

3. Towing at night for 3-4 hours or more WILL likely cause the Jeep's batteries to be depleted and the Jeep may not have enough battery power remaining to start.

4. Having some type of Jeep battery charging system in place will typically prevent this problem from occurring because the charging will offset the current draw from the Jeep being awake.

5. When the Jeep is asleep (the desired state for towing), the Jeep's brake pedal will not activate the rear brake lights. If you have an aux braking system that pulls/pushes the Jeep's brake pedal down, then you will have another nuisance problem. Imagine that you are approaching a turn and you have the turn signal on in the RV. The RV is blinking the Jeep's rear light via the towing harness you have installed. But, in the process of turning you also apply the brakes in the RV then the aux braking system in the Jeep will activate the Jeep's brake pedal. Because the Jeep has been awakened because of the light activation, movement of its brake pedal will cause it to activate its brake lights. The brake light activation (constant 12v signal to the rear lights) will cause the blinking to stop. So, for the duration of the turn where the Jeep's brake pedal is being moved, you will not have a turn-signal until the pedal comes back to its default position.

 

[Gaffer]

Yes.

Do you have LED tail lights?

 

[GO_RV]

Do you have LED tail lights?

Nope.
i specifically bought my Sahara without them

 

[Gaffer]

Watch the video on this webpage.
they have an install video on the bottom of the page
Install video on the bottom of the page
also here is a newer install video
Another install video on the bottom of the page

I like the second product better because of the diode. I would loom the charge wire however. This option is a lot less $ than the RVI product.

 

[Gaffer]

Nope.
i specifically bought my Sahara without them

I am doing the same. I will likely change to LED headlamp bulbs. There are some threads on here that show some economical choices.

 

[jwey]

Many good questions here and many owners have provided feedback that enables the collective "us" to know more about this problem. Just to be clear, we are only speaking about JL Wranglers and Gladiators with the REAR LED lights.

Based on the feedback/experience that we have witnessed, I'd say that the majority of owners may never know this problem exists. This is because the Jeep WILL exit sleep state whenever a rear light is activated by ANY towing harness, but after a couple of minutes the Jeep will go back into sleep state. As such, typical towing scenarios and durations would not necessarily cause the battery to drain because the Jeep simply isn't awake (drawing current) enough to pull down the battery.

The scenario that WILL bite you fast is towing at night... or towing with a coach that always has the headlights on (many of our Canadian friends as well as several higher-end coaches in the US). This is because the towing harness used will keep constant power to the rear marker lights... and the Jeep will stay awake. This is predominately why we see some owners say, "I have towing harness brand xyz and I've never had a problem" and others will say, "I installed towing harness brand abc and my Jeep battery dies." It is NOT one brand over the other - it is really the difference because one owner tows at night and another does not (or at least not for long durations).

But, perhaps the biggest reason the people never experience this problem is because the majority of owners have installed some type of charging system for the Jeep battery while being towed. This is a good (and fortunately popular) idea because a lot of the aux braking systems will consume local Jeep battery power for their operation. These battery charging systems will typically offset the current draw from the Jeep being out of sleep-state and the dead-battery problem never occurs.

In summary, I would postulate the following; (For JL Jeeps with the optional rear LED lights)

1. ALL Jeep towing wiring harnesses (even Mopar's) will cause the Jeep to exit sleep state when a rear (brake, turn, or marker) light is activated.

2. Typical day-time (lights off) driving scenarios are not sufficient to cause the Jeep's battery to drain as the Jeep will go back to sleep a couple of minutes after the light activation.

3. Towing at night for 3-4 hours or more WILL likely cause the Jeep's batteries to be depleted and the Jeep may not have enough battery power remaining to start.

4. Having some type of Jeep battery charging system in place will typically prevent this problem from occurring because the charging will offset the current draw from the Jeep being awake.

5. When the Jeep is asleep (the desired state for towing), the Jeep's brake pedal will not activate the rear brake lights. If you have an aux braking system that pulls/pushes the Jeep's brake pedal down, then you will have another nuisance problem. Imagine that you are approaching a turn and you have the turn signal on in the RV. The RV is blinking the Jeep's rear light via the towing harness you have installed. But, in the process of turning you also apply the brakes in the RV then the aux braking system in the Jeep will activate the Jeep's brake pedal. Because the Jeep has been awakened because of the light activation, movement of its brake pedal will cause it to activate its brake lights. The brake light activation (constant 12v signal to the rear lights) will cause the blinking to stop. So, for the duration of the turn where the Jeep's brake pedal is being moved, you will not have a turn-signal until the pedal comes back to its default position.

 

[jwey]

Many good questions here and many owners have provided feedback that enables the collective "us" to know more about this problem. Just to be clear, we are only speaking about JL Wranglers and Gladiators with the REAR LED lights.

Based on the feedback/experience that we have witnessed, I'd say that the majority of owners may never know this problem exists. This is because the Jeep WILL exit sleep state whenever a rear light is activated by ANY towing harness, but after a couple of minutes the Jeep will go back into sleep state. As such, typical towing scenarios and durations would not necessarily cause the battery to drain because the Jeep simply isn't awake (drawing current) enough to pull down the battery.

The scenario that WILL bite you fast is towing at night... or towing with a coach that always has the headlights on (many of our Canadian friends as well as several higher-end coaches in the US). This is because the towing harness used will keep constant power to the rear marker lights... and the Jeep will stay awake. This is predominately why we see some owners say, "I have towing harness brand xyz and I've never had a problem" and others will say, "I installed towing harness brand abc and my Jeep battery dies." It is NOT one brand over the other - it is really the difference because one owner tows at night and another does not (or at least not for long durations).

But, perhaps the biggest reason the people never experience this problem is because the majority of owners have installed some type of charging system for the Jeep battery while being towed. This is a good (and fortunately popular) idea because a lot of the aux braking systems will consume local Jeep battery power for their operation. These battery charging systems will typically offset the current draw from the Jeep being out of sleep-state and the dead-battery problem never occurs.

In summary, I would postulate the following; (For JL Jeeps with the optional rear LED lights)

1. ALL Jeep towing wiring harnesses (even Mopar's) will cause the Jeep to exit sleep state when a rear (brake, turn, or marker) light is activated.

2. Typical day-time (lights off) driving scenarios are not sufficient to cause the Jeep's battery to drain as the Jeep will go back to sleep a couple of minutes after the light activation.

3. Towing at night for 3-4 hours or more WILL likely cause the Jeep's batteries to be depleted and the Jeep may not have enough battery power remaining to start.

4. Having some type of Jeep battery charging system in place will typically prevent this problem from occurring because the charging will offset the current draw from the Jeep being awake.

5. When the Jeep is asleep (the desired state for towing), the Jeep's brake pedal will not activate the rear brake lights. If you have an aux braking system that pulls/pushes the Jeep's brake pedal down, then you will have another nuisance problem. Imagine that you are approaching a turn and you have the turn signal on in the RV. The RV is blinking the Jeep's rear light via the towing harness you have installed. But, in the process of turning you also apply the brakes in the RV then the aux braking system in the Jeep will activate the Jeep's brake pedal. Because the Jeep has been awakened because of the light activation, movement of its brake pedal will cause it to activate its brake lights. The brake light activation (constant 12v signal to the rear lights) will cause the blinking to stop. So, for the duration of the turn where the Jeep's brake pedal is being moved, you will not have a turn-signal until the pedal comes back to its default position.

Just installed a Roadmaster wiring harness for LEDs. Their instructions say to connect with the park lights (pin 4), not the brake/turn lights to prevent the wake-up problem. Apparently the sense line is only affected by the brake/turn lights. I tested and the jeep never woke up. Their video still shows connecting with brake/turn so it could use an update.

 

[CoolTech]

Just installed a Roadmaster wiring harness for LEDs. Their instructions say to connect with the park lights (pin 4), not the brake/turn lights to prevent the wake-up problem.

In my humble opinion, this is NOT a good idea. As you certainly know, the intensity/brightness of the brake lamp/turn signal filament is MUCH greater than the parking lights. This increased brightness level is a legal requirement for brakes/turn signals. This recommended wiring is neither safe nor legal.

 

[jwey]

In my humble opinion, this is NOT a good idea. As you certainly know, the intensity/brightness of the brake lamp/turn signal filament is MUCH greater than the parking lights. This increased brightness level is a legal requirement for brakes/turn signals. This recommended wiring is neither safe nor legal.

Your opinion has been duly noted.

 

[Jdw1]

So if a person stops the signal on the wire letting the bcm know the tail lights are working the system will not wake up, correct?

im sumwhat surprised the the mopar harness didn’t solve this!

what happened to cool tech, his website is not found?

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