Six Relays on Tow Harness?

retmil46 · **Posted:** Thu Sep 18, 2008 2:35 pm

Recently ordered the Mopar tow harness and supplemental harness for rigging the CRD up for towing.

I'm a little puzzled, because instead of 4 relays and a mounting bracket as others have referred to on here, and as pictured in the instructions, there was no mounting bracket, and there were SIX relays wired and ganged together, along with an 18 amp thermal circuit breaker wired into the output of the tow relay that supplied the 12V+ pin on the trailer connector. They were sealed up in a large piece of felt held together with cloth electrical tape.

Also, the color codes for the wiring in the tow harness revert back to the color codes in my Haynes manual for 01-04 gasser models - ie, brown/green stripe for backup lights instead of white/gray stripe as is in the vehicle and on Stan Wright's website.

I'm left wondering what those extra 2 relays are for. Part numbers in the bag and on the instructions are correct, could it be just an old version of the same harness?

Also, I noticed on one thread while doing a search that the wire from the installed fuse in the power distribution box is already ran inside the firewall, down at the drivers side kick panel. Is there any other prep wiring that's already ran inside the vehicle that can be hooked up to? I'd rather make use of what's already there, instead of duplicating wiring runs and blindly following the instructions that came with the harnesses.

Joe Romas · **Posted:** Thu Sep 18, 2008 3:17 pm

Parking/tail lights
Left turn/stop
Right turn/stop
Trailer battery charge
Backup lights

I don't know what the sixth one is for. Possibly supplies power to thr others?? I don't suspect it would be for electric brakes. Maybe look in the FSM electrical section under relays. My relays are bundled in a felt like blob also. I saw a XJ in a "yard" with towing harness and it was the same looking thing.

Check if your trailer 12 volts is always on. Mine was and originally and the pick voltage for it's relay was hooked to the power outlet on the dash. I wired mine to the rear of a fuse on the driver's door panel labled "trailer" or the like. Since I have gotten another F45 body flash and the dash power plug is now switched :wink:

Wouldn't it be nice if they could get their "flash of the month" act together

ATXKJ · **Posted:** Thu Sep 18, 2008 4:38 pm

FYI - if you don't have the Evic you need a 2nd harness PN 82207620 also
(no clue about relays)

http://www.jeepkj.com/forum/showthread.php?t=26895&highlight=trailer+hitches

cxturboboost · **Posted:** Thu Sep 18, 2008 5:23 pm

I used the rear fog light power that was designed for European vehicles. Please see my previous thread if you want the details.

Pete

retmil46 · **Posted:** Fri Sep 19, 2008 1:38 pm

Did a little poking around with the fluke this morning. Here's the best i can figure out with the six relays -

End relay (with pink/blue and yellow wires) - 12V+ to trailer thru the 18 amp thermal circuit breaker - wire changes from yellow to black at the circuit breaker.

Second relay - running lamps at trailer connector

Third and Fourth relays - LH stop and turn. Fourth relay is wired only thru it's normally closed contacts (ie, connection opens when relay is energized)

Fifth and Sixth relays - RH stop and turn. Again, sixth relay is only wired thru it's normally closed contacts.

On the add-on tow harness, it appears that instead of one brake and two turn relays, there are two relays for each side to handle stop and turn.

No connection to the relays for either electric brakes or backup lamps. Backup lamps are still handled thru the tranny gear selector switch, tow harness just adds a splice to run the backup lamps on the trailer off the same circuit. Stan Wright's mod for adding an additional relay and different power source for the backup lights would still be applicable and desireable - one 20 gauge wire handling 4 lights thru the tranny switch and a 10 amp fuse and close to a 20 foot wiring run doesn't give me a warm fuzzy.

fastRob · **Posted:** Fri Sep 19, 2008 5:11 pm

Not at all happy with what I see going on here.
My 7 way plug is just show and the wires are Mickey Mouse.
I do not trust anyone to fry the wiring but me and I do not have a clue.

Is a fluke an electric multimeter?

I need e brakes and a 12v power source for the trailer through the 7 way.
Some towing package indeed.

journeyjim · **Posted:** Fri Sep 19, 2008 8:51 pm

Looked at my connector, the notice for the vehicle mounted connector with the cover open, the pin for the electric brakes are at the 5:00 position, with stop and left turn at 9:00, and stop and right turn at 3:00, running lights are at 11:00, with the ground at 7:00 and back up lights in the center. Sorry don't know about the relays, thought this might help.

retmil46 · **Posted:** Sun Sep 21, 2008 8:30 pm

Well, I figured out how to make use of the factory fuse in the Power Distribution Box in the engine compt to power the trailer tow relay and 12+ power to the trailer, just like in the factory tow package, without having to run the second part of the supplemental harness thru the firewall and hook up directly to the battery.

Tuerns out that the wiring from the 30 amp trailer tow fuse in the engine compt is ran inside the cab, thru connector C100, and at least up to connector C201 behind the instrument panel. C100 is the large bolted connector behind the drivers kick panel below the hood release latch (or just below where you mount a SEGR if you desired).

The wire from Fuse 10 (Trailer Tow) on the PDC (14 gauge red/violet or red/purple depending on what your color perception is) runs thru pin 57 on C100 and then up to C201. For some reason, prior to going thru C100, it has a splice off (same size and color code) that also goes to pin 65 on C100, but doesn't connect to anything on the outgoing side.

To get at this wire - remove the drivers side kick panel. You'll need a short 10mm socket, swivel, and 6" extension to get around the hood latch handle and undo the bolt holding the two halves of C100 together. When unbolted, swing the rear half up and out of the way.

On the front half of C100, if you look at the plastic bracket holding it to the kick panel, you will see a small tab toward the bottom. Push this tab out of the way with a screwdriver while pulling the connector toward the rear. Once clear of the tab, the rest of the connector will slide off the mounting bracket.

Once clear of the bracket, rotate the connector so that the side where the wires enter is facing you. The red/violet wire going to the unused pin 65 will be the 3rd up from the bottom all the way to the RH side. The pin 57 connection that goes to C201 will be in a slot at the very top of the connector. Once mounted back in place, with the wire side facing the firewall, the pin 65 wire will be 3rd up from the bottom on the LH side.

Once I had the C100 connector disassembled, I used a blue splice tap connector to add on a length of 14 gauge wire to the pin 65 wire, long enough to route up and over to the center console, where I'll connect it to the pink/blue wire on the supplemental harness that supplies the trailer tow relay and 12V+ power to the 7 pin connector.

Instead of having to run another harness thru the firewall and having a 20 amp fuse holder hanging off the battery, I'll essentially have the factory 30 amp fused power supply and wiring.

retmil46 · **Posted:** Sun Sep 21, 2008 9:25 pm

I also decided that instead of using the wye connector at the 12V power outlet on the dash to supply operating power for trailer tow relay, I could easily make use of fuse 25 in the dash panel as per the factory setup.

When I installed the Kennedy lift pump, I used a two-place fuse holder/tap at fuse 25, and ran 14 gauge wire under the dash, out thru the rubber plug above the accelerator pedal, and then underneath back to the lift pump.

Since I essentially already had an "extra" circuit tapping off of the fuse 25 power supply, I did the same as with the red/violet wire at C100 - I installed a blue splice tap connector on the lift pump wire under the dash and ran an extra length of 14 gauge wire over to the center console.

I'll remove the wye connector setup for the 12V power outlet, and simply wire it straight to this extra wire off of fuse 25.

On the factory wiring setup, they show dash fuse 19 supplying power to the trailer brake lamp relay. This connection and separate wire doesn't exist in the supplemental harness. Instead, they ran the pink/blue wire from the battery back to the rear of the vehicle, and just before it reaches the C310 connector in the right rear quarter panel to hook into the tow harness, they splice off a red/black wire from the pink/blue power wire - the red/black wire splice goes to the pin on C310 that supplies the trailer brake lamp relay.

Essentially, they're supplying both the trailer tow relay/12V+ power to trailer, and the brake lamps, off the same 20 amp fused wire from the battery.

At least with tapping into the unused trailer tow wire at C100, I've bumped this up to a 30 amp fused supply for both.

I'm considering adding another two place fuse tap at dash fuse 19, and adding in a separate length of wire on the supplemental harness, such that the brake lamps will be powered separately off of fuse 19 as in the factory setup.

jinstall · **Posted:** Mon Sep 22, 2008 6:17 am

Europe uses 7 and 13 pole connectors. There are several different options on trailers with 13 pole, rear fog, back up light, different clearance lights, open options etc. Best to check a 1 pole diagram for this. Hey found a link.

http://www.monoposto.co.uk/goracing/towing.htm

retmil46 · **Posted:** Mon Sep 22, 2008 11:13 am

jinstall wrote:

Europe uses 7 and 13 pole connectors. There are several different options on trailers with 13 pole, rear fog, back up light, different clearance lights, open options etc. Best to check a 1 pole diagram for this. Hey found a link.

http://www.monoposto.co.uk/goracing/towing.htm

Makes more sense than our 7 pole connectors.

One thing I did note was their requirement to have the trailer charging circuit (ie, trailer tow relay) shut off when the vehicle wasn't running. That's why I decided not to use the wye connector on the supplemental harness to pull power from the 12V power outlet on the dash, to operate the trailer tow relay. From what I remember, there are circumstances where that power outlet will still be supplied with power when the vehicle is shut down - ie, the trailer tow relay will still be closed, and the vehicle and trailer batteries connected with the vehicle shut off, or at the least the trailer will still be able to pull power off the vehicle battery.

That plus the fact it doesn't give me a warm fuzzy having a constantly live pin on a connector external to the vehicle, where someone who doesn't know any better could go poking around and possibly damage/short something out or injure themselves.

Fuse 25 on the dash panel is active only in Run. It's where the factory installed wiring pulls power for operating the trailer tow relay, and I already have an auxiliary wire coming off that fuse under the dash to feed the Kennedy lift pump.

Joe Romas · **Posted:** Mon Sep 22, 2008 6:38 pm

retmil46 wrote:

Fuse 25 on the dash panel is active only in Run. It's where the factory installed wiring pulls power for operating the trailer tow relay, and I already have an auxiliary wire coming off that fuse under the dash to feed the Kennedy lift pump.

I hooked into that fuse for the trailer tow relay also

Why didn't you use the fuse and relay we already have for your lift pump :?:

retmil46 · **Posted:** Tue Sep 23, 2008 3:21 am

Joe Romas wrote:

retmil46 wrote:

Fuse 25 on the dash panel is active only in Run. It's where the factory installed wiring pulls power for operating the trailer tow relay, and I already have an auxiliary wire coming off that fuse under the dash to feed the Kennedy lift pump.

I hooked into that fuse for the trailer tow relay also

Why didn't you use the fuse and relay we already have for your lift pump :?:

At the time, no one had yet figured out that we had the relay, and the applicable wire in the harness under the rear seat for powering a fuel pump.

In the end though, it's a happy coincidence that I picked fuse 25 and already had the additional wire running under the dash - about 5 minutes work to splice on another piece of wire to run to the supplemental tow harness.

And I'm not really adding any load to fuse 25 itself. I used one of the 2 space add-a-circuit fuse taps at the panel. The original fuse 25 still supplies only it's original loads - the second fuse taps off the hot side of the fuse holder and supplies the lift pump, fuel cooler fan, and now operating power to the trailer tow relay.

I'm going to add another 2 space fuse tap at fuse 19 and run a wire from it along with the supplemental harness back to connector C310. I'm looking to use this for Stan Wright's mod to the backup lights, and might eventually use it if I decide to modify the braking and turn signal relays over to the factory setup.

I did some further checking again this morning, and discovered i was in error as to the red/black wire from the supplemental harness powering the brake and turn relays. Basically -

Pink/blue wire from supplemental harness - to 12V+ pin on 7 way connector via trailer tow relay ONLY.

Brown/pink wire in supplemental harness (from fuse 25/12V power outlet) - operating power for trailer tow relay ONLY.

Red/black wire in supplemental harness (splices off pink/blue just before C310) - supplies power to running lamps pin on 7 way connector via second relay (beside trailer tow relay) ONLY.

Blue wire - electric brake provision.

The brake and turn relays are tied directly into the circuits for the brake and turn lamps on the vehicle - ie, the brake and turn lamps on both the vehicle and the trailer are tied together using the same power source and control wiring. In other words, when you step on the brake pedal, the vehicle's factory wiring is going to be supplying power to 4 brake lights instead of just two. Same with the backup lights, you'll be powering 4 lights thru the reverse switch in the tranny.

In the factory setup, fuse 19 provides an independent power source to the brake and turn lights on the trailer, via one brake and two turn signal relays connected only to the 7 pin connector. The only connection to the vehicle's brake and turn lights is to provide operating power or on/off signal to operate the relays themselves.

Here I thought when I bought the Mopar harnesses that I was essentially going to get the factory wiring setup, but from the way they rigged it up it's little different from one of the cheaper aftermarket setups you can get on line, at least as far as the brake/turn signal part.

Joe Romas · **Posted:** Tue Sep 23, 2008 7:33 am

retmil46 wrote:

Here I thought when I bought the Mopar harnesses that I was essentially going to get the factory wiring setup, but from the way they rigged it up it's little different from one of the cheaper aftermarket setups you can get on line, at least as far as the brake/turn signal part.

Me too

But I've found with Chrysler a lot is not as it should be :wink:

retmil46 · **Posted:** Tue Sep 23, 2008 11:54 am

Exactly, like weak torque converters, fuel heaters, no lift pump, ball joints, EGR, air intake, etc... :evil:

This is just the latest "oh by the way" in my book.

When I pulled the felt off that relay bundle and looked at the rat's nest of wiring running to the 4 brake/turn relays, my first reaction was "what the h### is this mess?".

The way those 4 particular relays are wired in, it looks to be no different than one of the aftermarket 4 pin wiring harnesses that plug in directly to the connectors on the tail lamp units. And that's what I was wanting to avoid by buying the factory harness.

Just like the trailer tow relay being on full time (which might explain a few cases of dead batteries), and 2 sets of backup lights being supplied thru one 20 gauge wire and the reverse switch inside the tranny, I DO NOT like the idea of having the vehicle's lighting system tied directly into that of whatever trailer I might be towing - if nothing else from a reliability standpoint.

If I end up renting a U-Haul trailer for the move, and the trailer wiring system has been poorly maintained such that it develops a short, what's to keep said short in the trailer from taking down the vehicle's lighting system as well?

I'll be flying down to Texas this Saturday for a week for two more interviews. If I had the time, I'd be sorely tempted to do a root canal on the wiring of those 4 relays and switch it over to the 3 relay setup in the factory wiring diagrams.

What's odd is, on one feature, this wiring harness does actually improve on the factory wiring setup. Instead of connecting the trailer running lights directly to the vehicle park lamp wiring, it uses a relay with a separate power supply and the relay controlled by the vehicle's park lamp system - the second relay connected to the red/black wire spliced off the tow relay supply I mentioned earlier.

fastRob · **Posted:** Tue Sep 23, 2008 2:43 pm

[quote="retmil46One thing I did note was their requirement to have the trailer charging circuit (ie, trailer tow relay) shut off when the vehicle wasn't running. That's why I decided not to use the wye connector on the supplemental harness to pull power from the 12V power outlet on the dash, to operate the trailer tow relay. From what I remember, there are circumstances where that power outlet will still be supplied with power when the vehicle is shut down - ie, the trailer tow relay will still be closed, and the vehicle and trailer batteries connected with the vehicle shut off, or at the least the trailer will still be able to pull power off the vehicle battery.
quote]

Sometimes, especially when the tow vehicle has 2 batteries, they supplement the batterie(s) in a camper.
Conversely, a charged camper battery can be used to start or charge a low tow vehicle.
There are advantages/disadvantages both ways.
Someone could leave the 12v lights on and kill all the batteries.

With the 7 pin connector on the back I thought this rig was just a plug in away from a brake controller.
Without proper trailer/brake wiring this vehicle is useless to me.
All the time and money into this thing and .......
Patience, a solution will be found.

retmil46 · **Posted:** Thu Sep 25, 2008 11:03 am

For the time being, I'm going to leave the brake/turn signal relays as is. From studying the way they're wired up, it looks as though with a minimum of wire snipping and rerouting, along with tapping into one of the power supply wires for a separate power supply, they can be easily reconfigured to the factory setup in the FSM wiring diagrams.

Along with that, the brake and turn signal lights look to be fed with 16 gauge wire at a minimum - much better situation than the backup lights being fed by a single 20 gauge wire thru a tranny switch of unknown amperage rating.

I did add in a separate relay for the backup lights per Stan Wright's mod. I'm using the separate wire I'm routing from fuse 19 for the time being. I went into the tow harness itself, since the wire to the backup lights splices off to separate feeds for the vehicle and trailer in the harness itself. I extended the wires from both up to the relay, such that there is a separate wire from the relay feeding each set of backup lights to reduce voltage drop.

retmil46 · **Posted:** Fri Sep 26, 2008 10:35 am

Finished up the wiring install yesterday and tested everything out. Backup lights are now very bright - my mother commented that they look like a set of rear headlights now - this while testing them out in daylight.

One tip on the supplemental harness - if you do away with the wye connectors for the dash power outlet and connect to fuse 25, there's enough room that you can route the harness under the center console to the drivers side and not have to bother with disassembling the dash and removing the radio.

dieselenthusiast · **Posted:** Tue Oct 14, 2008 12:28 am

Okay, I read this thread and I’m still a little confused. I’m about to order the factory wiring harness for my Gasser KJ so I can tow my camper. So what’s the problem with the factory writing harness? Maybe the fact that the harness doesn't work with the trailer brakes? The mopar harness (RV 7-way connector) should be designed to plug into the factory wiring (through the taillights), so I’m not sure why you guys are talking about extra wires, etc.

jinstall · **Posted:** Tue Oct 14, 2008 6:14 am

Because the e-spec harness has a 7 and 13 pole option. The wire harness is built for both markets but both markets do not use all the relays in the harness.

Six Relays on Tow Harness?

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