97+ conversion with stock MJ tailight wiring configuration

[Delox]

(This is specific to those doing a complete 97+ XJ wiring, dash, engine etc. swap into a comanche, but may apply to others)

 

For those looking to retain the stock MJ tail light function (integrated brake and turn signals) instead of having to split the taillights into brake and turn sections like the XJ has, you may want to consider a device common on motorcycles. An integrated brake turn controller AKA a run-brake-turn controller such as this universal device

 

https://www.amazon.com/Universal-Smart-Triple-Play-Controller/dp/B00BFXJM3M

 

there are several available online with varying function, but as I am about to begin integrating my 98 cherokee harness with my MJ rear harness, this has been something I have been looking to accomplish. It appears this will allow all of the tail wiring changes to take place inside the cab. I plan to retain as much of the XJ harness as possible stowed away behind/below the drivers seat.

 

edit: This may require an LED style flasher to be installed, since the controller may or may not use the individual turn signal pulse to power the bulb in all conditions, which may cause a fast flash.

[zomeizter]

That device is neat for the flash patterns, but it's not required to accomplish integration of the XJ brake/turn circuit. I reckon an XJ uses one bulb for brake light and another for turn signal as opposed to the MJ using one dual-filament bulb for those functions. All one has to do is properly merge the circuit conductors of both harnesses, unless that device makes it easier to accomplish the goal at hand...  

[Delox]

Until you press the brakes and have the turn signal on at the same time.

[Delox]

I have bought and installed this item, and can confirm it works. This solves the issue that anyone doing the 97+ conversion has had to tackle. Having this device between the XJ tail light output wires (from body harness) and the MJ tail light wires (running out from the cab to the rear) makes the MJ tails function like stock.

 

No having to run and extend the XJ wires to the rear.

No having to run passenger side wires.

No having to run an additional wire for brake lights.

No having to split the upper and lower MJ lights to function independently as a brake light and a turn signal.

No having to find a way to hack the MJ tails to accept the XJ bulb sockets.

 

I will update with some pictures of the install once its finalized to help visualize how I wired this. Everything is wired in the cab and the stock MJ tail harness is intact.

 

[Delox]

Here is the very basic wiring.

You will pick one of the taillight pigtails as your primary (run, brake, turn, reverse, ground). The other will only be used for it's turn signal.

 

The running lights and reverse lights pass directly from the XJ pigtail to the MJ rear connector (which exists the cab under the driver's seat)

The brake, ground, and turn signals run to the new device as input.

On the output side, you will only use the left and right tail wires.

The orange arrow indicates the 3rd brake light output, if using.

The green arrow indicates the two fuel pump wires, if using.

Finally, the bundled blue and orange wires indicated by the red arrow require a switched (IGN) 12v source for the device to function. There are a few of these on the XJ harness you can find with a multimeter.

 

Works excellent. The only setting you need to set is by following the instructions on dimming the run lights. You will follow the instructions and turn the rotary switch all the way until the run lights turn off. (We don't need this functionality since we have separate wiring for running lights)

[ValpoManche]

Most excellent idea! Thank you for sharing and adding link to the controller.