7 pin trailer harness on 94 - JeepForum.com
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post #1 of 18 Old 03-17-2019, 08:38 AM Thread Starter
OverlandZJ
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7 pin trailer harness on 94

Built an offroad popup camper, then bought another Jeep to tow it. The new rig is a 94 with 5.2, has the receiver hitch done on recall.. but no wiring harness.

I put a 4 way harness on my 95 ZJ, and wired the pup with 4 way also. This time i'd like to install a 7 pin for future use.. charging camper battery and electric brakes.

I cant seem to find a direct fit 7 pin for the earlier ZJ, but iirc they were available from factory?

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post #2 of 18 Old 03-17-2019, 10:58 AM
wingless
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The '94 factory 7-pin trailer wiring had a relay pack, wrapped in padding, hidden behind the interior panel, under the right rear window, as-shown hanging down in the image.

Aftermarket or junk yard might be your only solution.





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post #3 of 18 Old 03-20-2019, 01:27 PM Thread Starter
OverlandZJ
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Thanks Wingless, I was under the impression it was on drivers side rear and I didn't have anything.. i'll pull the right panel this weekend.

So i'll need to find the section from the relay pack inside to the hitch? Or is all that wrapped inside?
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post #4 of 18 Old 03-20-2019, 01:39 PM
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Can confirm, the relay harness is on the passenger side for '94s. It got switched to the driver's side later.

You'll need everything from the 7pin connector up to the plug above the wheel well - there should be an unused factory connector there on yours that the whole wiring assembly (relay pack, 7pin connector harness) plugs in to. It's very likely that the junkyard or eBay are your only options as the harness is long out of production.

1994 5.9L ZJ | IRO 5.5" CPLA | NP242 | 33" Cooper Discoverer STT Pro
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post #5 of 18 Old 03-20-2019, 02:09 PM Thread Starter
OverlandZJ
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Excellent.. thanks for the input.
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post #6 of 18 Old 03-20-2019, 04:36 PM
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Quote:
Originally Posted by wingless View Post
The '94 factory 7-pin trailer wiring had a relay pack, wrapped in padding, hidden behind the interior panel, under the right rear window, as-shown hanging down in the image.

Aftermarket or junk yard might be your only solution.
One option is to get one of these aftermarket 4-pin vehicle-specific trailer wiring kits, snip off the 4-pin connector, wire that into a 7-pin connector, then properly add the additional wires.


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post #7 of 18 Old 03-20-2019, 06:32 PM Thread Starter
OverlandZJ
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Quote:
Originally Posted by wingless View Post
One option is to get one of these aftermarket 4-pin vehicle-specific trailer wiring kits, snip off the 4-pin connector, wire that into a 7-pin connector, then properly add the additional wires.

That would allow me to wire in as I need too.. charging camper batt's over electric brakes in my case.

Excellent input again.. Thank You
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post #8 of 18 Old 03-24-2019, 07:23 PM
RedRiverT
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Or you can get some mini relays (or "micro" maybe), connect wires to that un-used factory plug above the wheelwell, and make your own harness with a 7-pin.
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post #9 of 18 Old 03-25-2019, 10:06 AM
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I have a 95 ZJ Limited, according to it's build sheet it came with no factory trailer hitch but came with a

AHC Trailer Tow Prep Group
DMEP 3.73 Rear Axle Ratio
NMCP Heavy Duty Engine Cooling

It also has a factory oem transmission cooler and oem two row aluminum core radiator.

The local dealership installed a trailer hitch (without trailer wiring) that was covered by a safety recall

So I too am looking to install some trailer wiring, but am not certain what oem wiring for a trailer already exists.

I looked through a 93-96 Jeep parts manual (Cherokee, Grand Cherokee and Wrangler) but could only find reference to parts for a 7-way connector (p/n 56018483) for the Cherokee

There are several related part numbers for a ZJ without trailer hitch

However while searching I did notice some discrepancies of part numbers for the steering gear.

GEAR, STEERING for the ZJ

5208 7753 1 ZJ w/o Trailer Tow 1994-95
5208 8324 1 ZJ w/o Trailer Tow 1996
5208 7754 1 ZJ w/Trailer Tow (AHT,AHC or AHX) 1994-95
5208 8328 1 ZJ w/Trailer Tow (AHT,AHC or AHX) 1996

Apparently factory installed trailer tow uses a different steering gear?

I'm uncertain what AHT, AHC or AHX means?

I'm uncertain if the steering gear w/Trailer Tow is included with AHC Trailer Tow Prep Group

I did find a post where a person posted:

"Not sure about a 94 5.2 but on my 96 4.0 it included the "AHC Trailer Tow Group" which isn't the full tow package. It included the trans oil cooler (in front of the AC condenser you can see through the grill), 3.73 rear gearing, higher amp alternator (117 amps), wires/connection for trailer pigtail above the right wheel well/behind plastic access door where spare tire is supposed to ride, possibly a heavier duty power steering pump, and no hitch."

I guess I would need to try an oem part number from the installed steering gear and take a closer look at what oem trailer wiring is included with my 95 ZJ.

I haven't taken a look at any wiring from the passenger side near the rear hatch.

7 way plugs usually include other wiring such as a battery charge wire that works from a relay.

So if nothing exists for a 7-way connection you could just install your own trailer wiring relay(s).
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post #10 of 18 Old 03-25-2019, 07:05 PM
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muddflow,

The "Tow Prep Group" includes everything but the hitch and the wiring pigtail, I think. And that "steering gear" you're talking about is the power steering pump, I'm pretty sure.

On your '95, behind the interior panel, above the passenger side wheelwell, there is the wiring bundle that runs to the rear lights (& hatch latch, roof light, etc.) and it should have a branch off of it that ends at a big connector plug. This is where the factory tow wiring harness would have connected. I don't remember if only "Tow Prep Group" has this or if all of them do.

That big connector plug includes a full-time hot wire (Red) that is the power source for the trailer lights and brakes and whatever else. I think it has 9 connection pins.

Duh! Here it is. This is my '97 so it's on the driver's side.
Attached Thumbnails
plug behind spare tire.jpg  
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post #11 of 18 Old 03-25-2019, 07:08 PM
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It's clearer on here than on my screen. I guess it is 8 pins.
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post #12 of 18 Old 03-25-2019, 10:12 PM
muddflow
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I think your right. Looking at the OEM parts manual it appears it's both the power steering pump and steering gear.

However replacement cost might be significant, unless one is able to find both from a JY.

referencing part numbers a new Mopar pump is around $100.00 and a new aftermarket steering gear from JC Whitney is ~$331.00.


OEM parts manual

PUMP, POWER STEERING WRANGLER, CHEROKEE GRAND CHEROKEE (ZJ)

Pump, Power Steering

5208 8022 1 ZJ w/4.0L Eng., w/Trailer Tow Pkg. 1994-95
5300 7383 1 ZJ w/4.0L Eng., w/o Trailer Tow Pkg. 1994-95
5203 7812 1 ZJ w/5.2L Eng., w/o Trailer Tow 1994-95
5208 7658 1 ZJ w/5.2L Eng., w/Trailer Tow 1994-95
5208 8139 1 ZJ,ZG w/4.0,5.2L Eng., w/o Speed Proportional Steering 1996
5208 8250 1 ZJ,ZG w/4.0,5.2L Eng., w/Speed Proportional Steering

GEAR, POWER STEERING WRANGLER, CHEROKEE, GRAND CHEROKEE (ZJ)

GEAR, STEERING

5208 7753 1 ZJ w/o Trailer Tow 1994-95
5208 8324 1 ZJ w/o Trailer Tow 1996
5208 7754 1 ZJ w/Trailer Tow (AHT,AHC or AHX) 1994-95
5208 8328 1 ZJ w/Trailer Tow (AHT,AHC or AHX) 1996
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post #13 of 18 Old 06-19-2019, 11:26 AM Thread Starter
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So, they changed the plugs at taillights in 94..

Went to install the newer t-one 4 flat connector from my 95 (For Sale) and toss it in my 94.. didn't wanna drop another $75 if I didn't need to, and I could get out and camp last weekend.

So if it's time to spend money on this i'll just go to a 7 pin. I know a guy parting ZJ's and has a Niner with OEM 7 pin setup... will it work in my 94? No more surprises with plugs?

Unless.. someone knows a good aftermarket source for a combo 7 and 4 pin connector for the ZJ?

I'm electrically challenged
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post #14 of 18 Old 06-19-2019, 11:32 AM
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Quote:
Originally Posted by wingless View Post
One option is to get one of these aftermarket 4-pin vehicle-specific trailer wiring kits, snip off the 4-pin connector, wire that into a 7-pin connector, then properly add the additional wires.
Quote:
Originally Posted by OverlandZJ View Post
So, they changed the plugs at taillights in 94..

Went to install the newer t-one 4 flat connector from my 95 (For Sale) and toss it in my 94.. didn't wanna drop another $75 if I didn't need to, and I could get out and camp last weekend.

So if it's time to spend money on this i'll just go to a 7 pin. I know a guy parting ZJ's and has a Niner with OEM 7 pin setup... will it work in my 94? No more surprises with plugs?

Unless.. someone knows a good aftermarket source for a combo 7 and 4 pin connector for the ZJ?
The linked aftermarket harness doesn't fit the bill?

This combination connector could be wired-in if the usage of an in-line plug adapter isn't desirable.


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post #15 of 18 Old 06-19-2019, 12:14 PM Thread Starter
OverlandZJ
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Quote:
Originally Posted by wingless View Post
The linked aftermarket harness doesn't fit the bill?

This combination connector could be wired-in if the usage of an in-line plug adapter isn't desirable.

The linked.. no. My rig is pre 3/94 manufacturer. I did find one that's plug and play (minimum splicing) but that leaves me with just a 4 flat.

If i'm gonna buy, i'd like a plug in 7 pin to gain a positive for camper battery charging while running. Interior lighting and 12v for a shurflo water pump for showering etc. A combination connector would be preferable for the versatility.

I ordered a 3500# Dexter axle with bracketry for trailer brakes back
when.. another future upgrade that makes a 7 pin more sensible.

Maybe I should just drop it off and tell the trailer shop what I want..
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