Towing with a Sport.

I have a '90 Sport 4.0 and 5spd. I want to put the receiver hitch from a '88 on it but can't find the connector for the wiring harness. The '90 is wired for everything else including rear wiper/washer/defroster even though it doesn't have these.
Would it have to be equipped with the factory tow package to have the trailer wiring?

yes.

you'll need a 3 to 2 trailer light converter and to take the drivers side panel off in the cargo area to get at the wires and make your own connectiou wons if you want to DIY.

That's what I thought. Thank you.

The factory hitch included a custom harness that exited the left rear quarter panel through a hole typically filled with a plastic plug. The nice thing about the factory harness is that it came with a grommet to fill that hole and seal the fender area. The factory harness also had a set of male and female connectors so that it could simply tap into the existing wiring harness. Some of the aftermarket companies will still give you the male/female connectors but I haven't seen the grommet available anywhere. You can find these from time to time on eBay.

HTH
Todd

I have the whole exterior harness including the grommet. Took it off my '88. But when I looked in the rear quarter panel of the '90, there is nowhere to connect it. Was trying to keep it factory.
Thanks guys.

IF your 90 XJ has tail lights it has the trailer wiring connector.. See the trailer wiring connector gets, INSERTED into the existing wiring to the tail lights. The connection is at the rear under the driverside panel. That said the plugs could be different for 1988 and 1990, but the wires are all the same.