[palmaceae]

Hello, new here!
I have a '98 Grand Cherokee with a 4.0 and 4wd and want to install a trailer hitch. I would like to know what the towing capacity is for the Jeep? Also I was told I could not hook up the wiring for the trailer to the tail lights because that could damage the computer, is that true? I was told I need to run a totally independent wire for the trailer, just wondering if that is true?
Thanks

[ajmorell]

5000 lbs, but if you're going to consider towing anywhere near that I would make sure the trailer has brakes on it.

[palmaceae]

Thank you, anyone know about the electrical hookup? Can it be hooked up to the tail lights?
Thanks

[ryandavenport]

buy the wiring harness kit for it. it hooks into the tail lights. but i think thats the only way that it works. mine came with a trailer hitch but without wiring when i bought it. i was told by the guy at the local 4x4 store that it needs a special harness, so i bought it. like 40 or 50 bucks. thats all. good luck

[ZeeJay1997]

Do you know if yours has the factory tow package?

If it does it's already wired all the way to the bumper. If it doesn't there's a connector in the left rear quarter panel. One caveat, I only know this to be the case for a 97.

Also, there's a light blue 12 gauge wire on the pillar next to the hood release for an electric brake. It will be there tow package or no tow package.

Also, the factory tow package will have a relay or two at the junction box in the circuit, 3.73 gears, over sized tranny cooler.

[kc8ztw]

also note when you are buying a harness you can not buy a generic harness you hace to buy one for a jeep because your jeep has seperated blinkers from tail lights but you trailer does not. with the jeep harness you will buy there is a little moduel that combines the blinker with the tail and brake lights and prevents back flow throught the system.

[colt808]

The OP is a few months old, but maybe others are looking for the same info.

It is correct that 5000lbs (Class III) is the max GTW for towing with the 4.0L engine, but the minimum requirements (per Jeep specs) are:

1) Transmission cooler
2) Hi-temp rated steering
3) Heavy duty cooling (radiator)
4) Synthetic lube in for the axles

I'm know you can get away without making the above modifications for towing short distances at low speeds a few times. Personally I've gone about 30 miles towing equipment for work. Slight inclines and going over 35mph always caused the temp to shoot up. The job took a month, and I towed that load 5 days a week. About week after the job was done, my water & power steering pumps crapped out. It got me worried, so I decided to check out my rear differential...after removing the cover about a quart drained out and it smelled pretty burnt. Luckily the gears were ok. I also drained and adjusted the transmission around that time.

I guess it's really up to you if you want to risk it, but I don't think the 4.0 is the best choice for towing. I still have the hitch, but I treat it like a Class I/II (under 3500lbs) max. Good enough for hauling a couple of dirt bikes, jet skis, and the occasional fridge.

Also, ajmorell is right about the brakes...you're better off with them regardless of the load.

About the wiring, you do need to a specific connector set. Your local stealership has the part if you're willing to pay the $80-100 for it. I picked up mine from Valley Industries off eBay for $30 shipped. Hopkins makes a plug-in harness (p/n 42515), that requires no cutting or splicing.

Hope that helps.

[cyberZJ]

The Heavy Duty Cooling System has 10qts, the standard 9.3qts. Isn't that taking into account the amount of coolant that is in the AUX Transmission Cooler?

[LouC]

On my 98 it came with the heavy duty cooling rad and the bigger trans cooler in the rad...there was no aux cooler for the tow package for this year but you could still add one if you wanted to...I did not have the high temp seals for the p/s pump but never had a problem with that...I added the hitch...the ChryCo relay and converter for the trailer lights (7 pin includes electric brake wire)...and put Air Lift airbags in the rear coils (this helped a great deal with not having the trailer tongue weight cause sag and bouncing)...I used syn 75w-140 gear oil in the differentials...ATF+4 in the trans and transfer case...and with this set up I towed a 20 boat that weighs close to 4000 lbs. The 4.0 is not optimal for this but it will do it..my second Jeep is the 07 WK with the 5.7 Hemi..this one tows the same boat like it's not there....finally you will NEED trailer brakes that WORK....I towed that boat a few times with no brakes when I first got it and that load will push you like you would not believe. I added a set of 10" surge drum brakes and it made a big difference...

[LouC]

Originally Posted by cyberZJ

The Heavy Duty Cooling System has 10qts, the standard 9.3qts. Isn't that taking into account the amount of coolant that is in the AUX Transmission Cooler?

NO coolant in the aux trans cooler...there's trans fluid in there...the trans is cooled by the coolant in the rad...the cooler is on the 'cool' side of the rad...the hot coolant comes in the pass side and the cooled of coolant exits the bottom driver side on the 4.0 rad and the trans cooler is on that side inside the rad....

[cyberZJ]

So would you need to add more trans fluid or would you be all right.

[LouC]

Well yes if you add an aux cooler you will have to add some....it depends on the size of the cooler and how much leaks out when you add the cooler...

[BigRed4x4]

I just bought the 4 point connector with 4' of wire and hardwired it straight to my tailights behind the spare tire. All my lights work like they are supposed to, and it wasn't $50 like the first wiring harness I bought and never got.

But mines a '93 so maybe there's a difference.