You can download the instruction sheets that come with the 82209280 harness here. Note the difference between ’07 and ’08 in figures 24 A & B.
This was really much, much easier than I thought it would be. Search around for the best price that you can find. I went with the factory wiring simply because I knew that it would integrate with the electricals on mine. Some after markets units have been known to work well too.
You’ll need a good 1 ½” hole saw that will handle metal, I picked the hole saw and pilot up at ACE hardware for less than $20; A tube of RTV sealant, I use some clear silicone, it’s always the right color; a dab of paint for sealing the edge of the hole; a metal coat hanger or about a 3’ piece of wire to “fish” the harness threw the engine compartment; and some Duct Tape is always handy.
I used some Duct Tape and taped all of the engine compartment wires together so that they would hang up a little less when I got to routing it under the chassis and I drilled out the hole in the fuse holder to ¼” so that I could use the auxiliary bracket on the positive battery cable to hold it in place instead of the wire tie shown in Fig 32.
Start by removing the Spare Tire Cover, Spare Tire, insulation pad and Rear Hatch lower scuff plate then drill the 1 ½” hole as shown in figure 5 of the instructions. Put some quick drying sealer around the hole and when its dry thread the long part of the harness down threw the hole. I had heard that this was easier to do with the trailer receiver off but I didn’t notice it being a big deal with the receiver installed. Now put the RTV on the inner lower lip of the boot on the wiring harness and push it firmly down into place. You’ll feel the lip on the boot seat when you push it down in the hole. Take the part of the harness that’s in the spare tire well and slip it into the “hole” at the back corner where the rear Quarter Panel meets the floor show in the picture. You don’t have to take the Quarter Panel off to connect to the tail lights or put it where the instructions show in Fig 6. 7 & 8. You don’t need to stretch out the rest of the harness as shown in Fig 8 either. For the curious (like me) all that’s inside that wire braid loom is 4 relays. You can put the insulation pad, tire, jack, scuff plate and spare tire cover back in now, you’re done with that area.
Now you’ll want to connect the Trailer Wiring Plug to the built in bracket that’s on the receiver. Fig 13 & 14 show it the bracket as being vertical but mine was horizontal. Either way your receiver was made makes no difference. Just push the plug in and keep wiggling it around until the “MOPAR” logo is threw the hole and it should lock in place just fine. This part of the harness I did a tri-fold on and put the part with the silver insulation up under the muffler heat shield. The rest of it I tie wrapped it to the receiver.
Next you’ll need to tape all of the leads together on the front end of the harness and snake the wiring up to the front drivers side of your Jeep. Start by putting the other section of silver insulation under the side of the muffler heat shield and then over the EVAP canister and over and threw the suspension components keeping it away from where a moving part could catch it. The Figures in the instructions don’t show much detail but I thought the routing was pretty easy. Fig 19 shows removing a small close out panel that I removed from mine when I did the Skid Plates. It’s pretty straight forward. Remove the nuts with a 10mm socket and put it back on after the wire is run.