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E-Brake as break away tow brake

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Old Mar 29, 2025 | 08:13 PM
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Question E-Brake as break away tow brake

Has anyone used the E-brake on a 2015ish as a break away safety tow brake?

Does anyone have the schematics and or logic for the system? I’m up to speed on the power steering while towing.
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Old Apr 4, 2025 | 11:57 AM
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100+ views and no one has an idea, anyone with the schematics and logic for the e-brake system?
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Old Apr 4, 2025 | 02:03 PM
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As in you're towing the jeep?
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Old Apr 4, 2025 | 02:23 PM
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Yes. Most states require the towed vehicle to have a breakaway mechanism to apply the breaks on the vehicle being towed. There are some expensive solutions that actually push on the brake pedal if the car breaks away while it is being towed. But if we can use the E brake system on the Cherokee, that would work even better and hopefully be a more economical and simpler solution.
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Old Apr 4, 2025 | 02:40 PM
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I imagine your first call shouldn't be here, but to your insurance company as they may have something to say about using a non-commerial diy solution like this.

That said, I don't own a '15 and am not sure how the ebrake operates to advise further
​​​​​​
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Old Apr 4, 2025 | 04:05 PM
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Probably right on that one…
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Old Apr 5, 2025 | 01:19 PM
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ALCON:

It appears it is possible to use the E-Parking Brake as desired.
Below is a snippet from the JEEP CHEROKEE KL 2014 ACCESSORIES AND EQUIPMENT Electronic Control Modules - Service Information - Cherokee, pages 2932 - 2933.

"At any time, the EPB switch can be actuated. Depending on the speed of the vehicle when the EPB switch is

actuated, the EPB module will output different commands under the following conditions:

Static Apply (under 5 kph) - Actuates the EPB motors attached to the rear calipers.

Dynamic Apply (over 5 kph) - Actuates the hydraulic braking system.

EPB module fail-safe include that the EPB can be applied ignition off, EPB cannot be released with ignition off,

brake pedal must be applied and seat belt must be on when releasing the EPB.

Courtesy of CHRYSLER GROUP, LLC"

Detailed explanation of the logic is available in the same publication. I'll give it a try when I get her running again...
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Old Apr 12, 2025 | 07:18 PM
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Here's the pinout for the switch itself. I suspect it's a DPDT switch, and the EPB module reads it and commands the actions over the canbus. You'd need to pull it and measure to confirm. If it is, then possibly controllable with a relay or two.






Last edited by lawsoncl; Apr 12, 2025 at 07:36 PM.
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Old Apr 12, 2025 | 07:36 PM
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Or rig something that mechanically pulls the switch up.
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Old Apr 15, 2025 | 09:22 AM
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ALCON,
Got her running again after changing 2 cams and all rocker arms. The E-Parking Brake idea appears to be very feasible.

I took her to the top of a hill here and put the transfercase in N. While rolling down the hill, engine off, I applied the switch. If you apply it momentarily, it will momentarily apply the breaks. If you pull it and hold it, it will apply permanently. I did not do multiple runs to figure out how long it took to permanently apply it. I suspect it was 2-ish seconds or more. It requires the engine running and seat belt latched to release the brake when applied.

Conclusion: This is an exceptional solution for flat towing and wanting the break away applied.

When I get it back from my daughter, lent to her for a while, I'll let you know how I wired it. I want to figure out how to send the signal to the CAN-buss so I can tap onto in the engine compartment and not have to penetrate the passenger compartment.

At any rate, much thanks to LAWSONCL for his schematics for the hard wiring. Does anyone know how I would send a signal to the CAN-buss to get the ECU to actually apply the E-Brake like the flat tow harness from Mopar does to the E-steering? I think it will be easy if we can figure out the appropriate wire and add a CAN connector similar to what the flat tow harness does.

Last edited by brucehblack@icloud.com; Apr 15, 2025 at 09:28 AM. Reason: misspell
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Old Apr 16, 2025 | 06:14 PM
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Originally Posted by lawsoncl
Here's the pinout for the switch itself. I suspect it's a DPDT switch, and the EPB module reads it and commands the actions over the canbus. You'd need to pull it and measure to confirm. If it is, then possibly controllable with a relay or two.

Thanks for the switch data. Do you have the rest of the schematic from the module onward? There are 30 pins, 8 of them are for higher amperage and I suspect those are for the actual power to the actuators.

My thinking is to buy a second module and mount it up front and have it actuated by the break-away switch and have it send the CAN buss the necessary data. This, because I don't want to penetrate the cabin or run wires all the way down the chassis to the module in the back, and I don't know how to encode messages to the CAN buss. A second module would encode and send the data on the CAN buss.

Thanks for the help!

Bruce
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Old Apr 16, 2025 | 09:18 PM
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Sent you a PM. I have a feeling two modules on the CAN bus would conflict though.

Last edited by lawsoncl; Apr 16, 2025 at 09:22 PM.
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