I have 98 Jeep Grand Cherokee, limited ed. and I'd like to order a trailer wiring kit. How can I check if it came with a towing package. When I opened the cover on the left rear side by the lamp, I noticed a box with two plugs, is that it?

Thanks,

The easiest way is to get a build sheet. It outlined how to do so in the FAQ.

I slightly skimmed over the GC FAQ stickied on this forum and didnt see anything on getting a build sheet. I might be blind but I will check again.


Edit : Looked again and found it....maybe I am blind lol

If it's got a trailer tow prep package, it'll have a tranny cooler behind the grill on the passenger side. It will also have the little white box in the drivers side rear (behind the tail lamp) to accept the wiring harness. Is it a V8? If so it'll already have the 3.73 gears.

Build sheet is the blue link in the FAQ.

4.0 engines. I have the little white box in the driver side rear (behind the tail lamp). This box has two harnesses on the bottom.

Not necessarily. I have the tow package but I do not have the external tranny cooler. All ZJs with the tow package do have 3.73 gears though.

Correct after 96 I believe they dropped the tranny cooler in the tow package, stupid idea. My 98 ZJ has the factory tow package and I had to have a cooler installed.

Is the quickest, easiest way to look in the PDC and see if you have the relay? (or wherever it is, if not the PDC) I don't recall.

Anyway, goblin, there are 2 levels of factory tow options, one is the full trailer towing package, which would have had the factory hitch with the wire harness & plug, and the second is the "Tow Prep Group" which didn't have the hitch or the harness, but did have the other hard-to-install items like gear ratio, trans cooler (possibly), different power steering pump, higher output alternator, relay and wiring split.

The wiring split would be above the driver's side rear wheelwell on your '98. In the main wiring bundle going back to the rear, for a factory trailer tow set-up, they Y'd off from the light wires to create the towing wiring harness. It had a group of relays, then the wires on out the back to the trailer plug-in on the hitch. The Tow Prep Group had that wiring Y, but it ended at a connection plug above the wheelwell. Let me say it right, a full tow package has that connection plug too, but it will have the towing wiring harness plugged into it.

What the factory towing wiring harness does, is it has a power wire and then the wires Y'd off of the rear light wires to act as signal sources, so by using the relays, it copies the rear light functions to the trailer lights. A lot of aftermarket trailer wiring kits simply split the electricity to send some to the trailer. They may have transformers or other such electrical doohickies to try to help that work better. With the factory harness, the trailer lights are powered separately.

For your reading pleasure, or agony, as the case may be:
https://www.jeepforum.com/forum/f13/...-wiring-37907/
https://www.jeepforum.com/forum/f13/...wiring-245544/
https://www.jeepforum.com/forum/f13/...rness-1270994/
https://www.jeepforum.com/forum/f13/...wobble-269285/
https://www.jeepforum.com/forum/f13/...p-how-1471573/
https://www.jeepforum.com/forum/f11/...lights-871172/

My 97 4.0 has the Tow Prep Group and it has the trans cooler. I don't know for sure if that was standard with the group or special add-on, but the way it is listed on the window sticker, it looks to be a standard part of the group.

Oh crap! This thread is 12 years old, except the last reply before mine.

It was no longer standard after 1996 and a horrible idea to no longer include it at least as a factory option, probably was a dealer add-on which if I recall many of these things were added at the dealer level rather than the factory...My 98 didn't have a cooler and after I found they stopped installing them with the tow package I wasn't exactly thrilled with the 150k on it with no cooling.

My 98 has a tranny cooler and 3.73 gears. I know because thats one of my many tranny leaks or was....

Does anyone k ow which line is the return line and if there is specifics on which one connects to which on the cooler?

IIRC the lower hard line from the trans is the input to the radiator cooler. THe upper line comes from the cooler and wraps around to a rubber line into the cooler.. That goes back to the upper line on the unibody rail. As far ash input/output of the separate cooler it does not matter

It SHOULD HAVE GOTTEN a tranny cooler, but 98's didn't get one. They were cutting costs at Chrysler at the time.

my 98' 4.0 has trans cooler built into the radiator.