2018 Jeep Wrangler: Installing and Wiring Mopar Lights
by Dan Edmunds, Director, Vehicle Evaluation
No doubt you've heard about the many design changes and new features that make the JL-series Jeep Wrangler much better than its JK predecessor.
But it's likely you've only heard about the auxiliary switch panel in passing. It's part of the optional "Trailer Tow and Heavy Duty Electrical Group" available for the Wrangler and Gladiator ($795), a package that includes a trailer hitch, a larger battery and a stronger alternator. I recently put the auxiliary switch panel to the test by installing a pair of cowl-mounted LED off-road lights.
What follows is a summary of the mechanical installation and electrical hookup of the Mopar 5-inch off-road LED light kit (P/N 82215385AB) using Jeep's lower A-pillar mounting bracket kit (82215427).
In this case, "lower A-pillar" is what I'm calling the cowl. The lights themselves can mount practically anywhere on the vehicle, so you need the bracket (sold separately) to mount them as I did.
The first thing to do is to find the point where the electrical connection is made. The auxiliary switches are pre-wired to a termination point you'll find under the hood on the passenger side in an empty space just outboard of the battery. There are four leads with ends that are insulated and sealed so that they don't represent a hazard.
There's an unused ground post available nearby to complete the circuit for the accessories that connect to these leads. It's all very easy to reach, and the proximity of the leads to the battery is a good reminder to remove the battery's negative terminal before you get started.
This underhood setup sure beats mounting a switch somewhere, crawling around under the dashboard and trying to pull wires through a grommet in the firewall, right?
But in the event that you do want to install accessories in the cabin, you'll find another gang of these same four wires behind the passenger kick panel, under the glove compartment. In fact, the interior wire drop includes two additional direct leads you can use for add-ons you wouldn't want to route through the switch panel, such as a CB radio.
At this point you might be wondering, "But, Dan, are these auxiliary switch leads always hot or switched with the key?"
The answer is surprising: It doesn't matter. You can program them to be whatever you want after you're all done. But we're getting ahead of ourselves. Let's install the lights and get them working.
First, we want to remove the corner trim panels between the hood and windshield pillars. They're held on with four Torx-head bolts, and you can use the Jeep's included tool set (for the hardtop/door/windshield) to remove them.
With the cover out of the way, we can route the wire harness for the lights. Here you need to work the cable along the seam — as if working a piece of dental floss between your teeth — and into an existing access hole in the flexible foam blocker panel. I also routed the wire behind the corner trim support bracket to keep it out of the way.
The trick here is ensuring that enough wire protrudes outside the vehicle to make the light connection without any undue strain. You'll want to test-fit the pieces to make sure you don't have excess wire hanging out and looking weird.
The old bolts are paperweights at this point, but they're worth keeping if you ever intend to remove the lights. The new lower A-pillar mounting bracket kit uses the same holes and comes with longer bolts and spacers that keep the bracket away from the paint. The longest bolts and the stepped spacers go in the top, and the shorter ones with simpler spacers go in the sides.
Don't crank them too tightly, especially the side pieces, because the corner trim panel you're sandwiching beneath the spacers is made of plastic.
You may notice the new bracket has four holes. The top holes are intended for the lights, but I'm not sure why there are two of them. Perhaps a different accessory uses both holes. The holes on the side are positioned to serve as a brace for the accessory snorkel. You won't be able to fold your windshield if you use the top holes, but you can use the side location if you want to retain that function.
Top-mounting the lights works best for us. It provides better light distribution, and we're not all that into the whole windshield-folding business anyway. Also, we're thinking about a snorkel.
The light mounts themselves feel rock-solid, and the vertical adjustment pivot includes an anti-vibration mechanism to keep the lights from shaking on washboard roads. At this point, it's time to give the light a preliminary aim, tighten things down and plug in the harness.
You'll do the same thing on the driver's side, the only difference being that you need to route the wire across the engine compartment to the passenger side so you can join the two light harnesses together. The included wires are long enough for this. I chose to run it along this edge because I found several brackets that worked well with zip ties.
With both of them ganged up on the passenger side, it's time to make the connection.
At this point, I hit a small snag. It's easy enough to unwind the harness tape to see the colors, but which one should I use? Two of the leads are clearly much thicker-gauge wire than the other two. The light kit instructions don't define how the various colored wires correspond to the numbered switches, but I was surprised to see that the Jeep's owner's manual doesn't explain it either. Perhaps that's rectified in later printings.
I eventually found my answer in an online forum. The fat wires can handle 40 amps, with the beige/pink one leading to switch 1 and the green/pink lead connected to switch 2. The smaller wire can handle 15 amps, with the orange/pink one controlled by switch 3 and the blue/pink one going to switch 4. I didn't need anything close to 40 amps for mere LED lights, so I picked the orange wire that works with switch 3.
The light harnesses are longer than they need to be, but they came with eyelet ends on their ground wires. I like to keep things intact in case I want to remove and resell something later, so I opted to use the factory eyelets, then fold the wires down to size and stash the extra in the generous space provided.
As you can see, the entire electrical operation is going to boil down to one bolted ground connection ...
... and one simple splice. Made at countertop level, I might add, while standing up.
The unused and still-sealed leads for the other three auxiliary switches are part of a larger and somewhat inflexible harness, so I made sure to stabilize the spliced area in such a way that the orange lead I'm using would not be under any strain. Now it's time to reattach the battery ground, turn on switch 3 and see if they work.
I can't tell you how easy this was. It was barely a 30-minute job. The mechanical installation was straightforward, and the electrical aspect consisted of just a single simple splice. Wiring is never supposed to be this easy, and there is no need to buy and install any aftermarket switches or relays. You absolutely need this option.
But we're not quite done yet. The last step is the really cool part.
You can configure your newly wired switch to operate in several ways. There's no wiring involved in making any of these changes, and you can choose a different setup for each of the four switches. Selections are made using touchscreen menus in the Uconnect system, and you can change your mind and alter the configuration at any time.
Do you want a given switch to be momentary or latching, also known as push on/push off? This isn't a horn, so I'm going with latching. Do you want the accessory to work at any time or only when the ignition is on? I made it so our new cowl lights would only work when the vehicle was running.
Choosing ignition-on functionality in this way leads to another choice. Do you want the accessory to "remember" the state it was in through a key cycle or always default to "off" at each restart? This last one is a bit less obvious, but I went with an "always off" default to be certain that the lights will only ever come on when I turn them on.
Excuse me if this feature makes me giddy, but I own a JK Wrangler of the last generation, and adding something like a switch to control anything is a chore. None of the aftermarket switch accessories are very attractive to look at or use. And it's a real project to run wires to the switch through a relay and outside to whatever it is you want to control.
The JL lives on a far more civilized plane of existence. This installation took me 30 minutes, and most of that consisted of bolting the lights into place. Do not underestimate the value and convenience of this option. Trust me, you need it even if you'll never tow anything.