Mopar Wiring harness

[Sledder1]

I have a 16 4dr Rubicon Hard Rock that I will tow behind a truck/camper. I just had dealer install the Mopar RV tow harness. When I tested the new harness system hooked to my truck/camper, I found that the center tail light (third brake light above spre tire) does not illuminate either in running mode or when brakes are applied. It also appears that the tail lights may be dimmer than they should be when compared to when they are powered by the jeep. The dealer has not been much help...
Can someone that has the Mopar harness tell me if the center brake light should illuminate via the tow harness. Since I will be carrying a hitch haul on the back of the Jeep I would like this center high mount brake light to work.
Thanks

[Lt Dan]

Originally Posted by Sledder1

I have a 16 4dr Rubicon Hard Rock that I will tow behind a truck/camper. I just had dealer install the Mopar RV tow harness. When I tested the new harness system hooked to my truck/camper, I found that the center tail light (third brake light above spre tire) does not illuminate either in running mode or when brakes are applied. It also appears that the tail lights may be dimmer than they should be when compared to when they are powered by the jeep. The dealer has not been much help...
Can someone that has the Mopar harness tell me if the center brake light should illuminate via the tow harness. Since I will be carrying a hitch haul on the back of the Jeep I would like this center high mount brake light to work.
Thanks

No, the center brake light does not activate with the Mopar harness. Only the left and right brake lights activate. You could probably rig up a feed for the center light with a couple of diodes. As for the running lights, I don't see any difference in light output between the Jeep and the motor home power.

[Sledder1]

Thank you for your help.
I will need to try and figure out a way to get the third brake light to activate.
May also look at upgrading the tail lights to some form of LED to hopefully increase brightness.
We tow in a lot of snow and fog and want to be as bright a beacon as possible.

[Millennial]

Legally you only need two lights on a trailer (Jeep) if that's what your worried about. As far as brightness I just changed my tail lights to new lights that just came out. That are crazy bright

[Sledder1]

Those look great. Were they a direct swap for stock with no modifications?
Brand, vendor?
Have seen upgraded LED bulbs on line but do not have experience with them to know if they work or better to go with complete new system like yours.
Thanks

[Millennial]

JW Speaker 279 J Tail Light Kit, Pair (JEEP DOT) https://www.amazon.com/dp/B015ZBZPS0..._UfzEwbFJ99T0S

I got them on Black Friday weekend for 273$ shipped from a Jeep parts online retailer but amazon's are a pretty good price right now too. They are plug and play. You can watch YouTube videos on them

Originally Posted by Sledder1

Those look great. Were they a direct swap for stock with no modifications?
Brand, vendor?
Have seen upgraded LED bulbs on line but do not have experience with them to know if they work or better to go with complete new system like yours.
Thanks

[Larry Young]

I had this problem when the wiring harness was installed, the solution in my case was to have 12 volts at rv connector.

[pashooter]

Originally Posted by Lt Dan

No, the center brake light does not activate with the Mopar harness. Only the left and right brake lights activate. You could probably rig up a feed for the center light with a couple of diodes. As for the running lights, I don't see any difference in light output between the Jeep and the motor home power.

Old-ish thread, I know, but I've been revisiting it as I just this weekend installed the Mopar harness in my 2015 Wrangler Sport.

I don't think the diode trick will work to illuminate the center-mount brake light - remember the brake lights are combination stop & turn lights, so if you add diodes from each to the center light it will flash when either the right or left turn signals are activated. Confusing to anyone behind you!

[vtwinwilly]

Originally Posted by pashooter

Old-ish thread, I know, but I've been revisiting it as I just this weekend installed the Mopar harness in my 2015 Wrangler Sport.

I don't think the diode trick will work to illuminate the center-mount brake light - remember the brake lights are combination stop & turn lights, so if you add diodes from each to the center light it will flash when either the right or left turn signals are activated. Confusing to anyone behind you!

I believe you are correct. Just adding diodes won't do the trick.

I've given this some thought and I think it could be accomplished by using a pair of relays connected in series to the center brake light. Both relays have to energized for the center light to get current. It's a decent idea in theory, but I'm not sure what happens when the brakes and the blinkers are applied at the same time.

I know it's legal the way it is, but for some reason it just triggers my OCD when that center light doesn't come on.

[pashooter]

I don't think your relays would do the trick either. With that scheme the center stoplight would still flash if the brakes and one of the blinkers were on.

One possibility would be to somehow use the trailer brake line (pin 2 of the 7-pin Bargman connector) to activate the center lamp using a diode. That pin is hooked up on my Pursuit, but I'm not sure what it's hooked to... typically that would be driven by the brake controller in the TV, but the motorhome doesn't have one of those. I suspect it's either hooked to the brake light switch or to nothing at all... something to investigate. At any rate, that would require an additional wire, as the brake signal is not carried through the Mopar-supplied cable.

So here's a question. We know that the center stop lamp isn't activated by the TV brakes through the harness but are we sure it's not still driven by the Jeep's brake lighting circuit when the brakes are applied? Here's my thoughts: I suspect that "lumpy sausage" part of the harness contains relays, not diodes. Simple diodes wouldn't keep the Jeep's brake lighting from "stepping on" the turn signals when activated by the TV, so the bulbs have to be disconnected from the Jeep wiring and tied to the TV when towing... relays would do that, and also explain why the "constant" 12V must be present on the 7-pin connector to pull those in when hooked up. If that's the case, there would be no reason to disconnect the center stop light from the Jeep wiring... perhaps that still comes on when the Jeep braking is activated by whatever braking system you have installed. Easy enough to check... hook up, then step on the Jeep brakes and see what happens. If I get a chance to play this weekend maybe I'll do that.

[vtwinwilly]

PAShooter,

You are correct. The relays only get you part way there.

As for the center light illuminating when connected to the TV (and pressing the brake)... as I recall it does. I use a Brake Buddy. One of the steps before towing is to purge the vacuum so the power brakes loose their vacuum assist.

In my hook-up routine I always make the mechanical connection, then electrical connection, then install Brake Buddy and press the auto-purge button. Auto-purge presses the brake several times in about 20 seconds giving me plenty of time to stand back and watch the brake lights (all 3) illuminate with every pressing of the brake pedal.

Do double check this if you get a chance because I'm going off of memory here (which is not as impressive as it used to be). I don't recall if the ignition was on in the coach, which may be preventing the constant 12v power to the 7-pin connector.

[quadnkev]

I have a similar question about the use of a braking device, mine is the SMI unit that has a vacuum device and actuator. Most likely a same thing but different thing. Is there going to be a need to change the connector wiring that signals the brake unit? This has turned into a problem child issue already, we tow the Jeep with a motorhome or our GMC truck-camper unit, hope it won't be a this setup for one and another setup for the other problem...

[grtharris]

quadnkev, make sure there is +12VDC on pin 4 of the 7 pin connector on the tow vehicle. Not all motorhomes and trucks have +12VDC wired to the connecter.

[quadnkev]

Thanks for the tip, believe that is OK. I ordered the harness from the dealer and they will install it for a decent price.