Jeep Grand Cherokee Trailer Hitch Installation and Wiring (7 & 4 Pin)
So I recently bought a 2000 jeep grand Cherokee with the 4.7 V8 engine. One of my primary reasons I bought this is because I would love to be able to tow stuff. The only problem is that it didn't have a hitch. So I've decided to install one. This is a guide for how to install a hitch and it is also for a little more information for me (I'm new to this forum and a jeep noob). There was no drilling involved in this and it looks sweet. Note that newer vehicles usually already have a plug slot for the brake controller, and I believe that starting with the 2001 model the blue brake wire was already run to the back of the Jeep. I hope this helps everyone. This process is for my jeep, but the basic concepts will work with basically any other vehicle that IS NOT equipped with a quick brake controller install connection.
I first bought a 5000 lb Class 3/4 hitch kit off eBay for $200ish. The installation of the hitch itself was really easy. You just remove the 2 driverís side rearmost bolts (18mm (or close enough)) and 3 passenger side that are holding up the skid plate to the frame. This is where the Hitch will be mounted to. I removed the plastic bumper cover because it was in the way and it made the job much easier (it's on with like 8 push clips in the back, a few rivets in the wheel wells, a hidden nut behind the splash guards that are removed with the rivets and two screws by the rear lights). So hold up the hitch while somebody (maybe you) reinstalls the bolts. Now the hitch is up. However now it is in the way of the bumper. My kit came with a stencil of where to cut the bumper out so it will fit over the hitch. I taped that onto the bumper and cut out the portion of plastic with a pair of Tin snips. It looks really good. In case it looked not so good, there was also a cover that could be put on around where you cut out, but I didn't like it so I just went without and it looks great. Now put the bumper back on (you'll probably need new rivets).
Be sure to disconnect the battery before doing any wiring stuff.
The harder part that I am now sort of stuck on is the wiring. The kit came with a 4 pin trailer power converter that plugs into a trailer wire harness located behind the driver side panel in the cargo area. You can get to it by removing the trim on the floor (2 screws on left and right, and 2 by the spare, total of 4 plus some clips) and then unscrew the loop screw things that you could hook stuff onto. There are two of them on the driver side panel in the cargo area. Now go to the driver side passenger door and remove that floor trim and there should be one more screw holding the panel in place. Once this is off you should be able to pull on the panel and it should pop off. It is still held in by clips but you can pop it all the way off past the seats and get it out of the way. This is gives access to a square hole covered by a black insulator. Remove the insulator and there on the left will be the plug for the other end of the power converter. This gives all the lights except for the reverse lights. Plug it in and BAM a working 4-pin power connector.
This next part is more or less optional. It bothered me that in order to run this wire to the hitch it would just stick out of the bottom of the tailgate when needed. This is what every video told me to do. However thatís ugly and I'm better than that. So after searching for holes (I would hate to have to drill a hole in my jeep) I found a black plastic plug thing that I could see from the underside. I figured it must be under the carpet in the back of the cargo area.
You'd think that getting under the carpet would be easy, But no. It's a pain. There is another black hook thing in the back that is actually riveted to the floor. So I took a nail and pounded out the rivet. On top of that I had to drill out the top of the rivet to finally get it off. Now the carpet can be pulled up.
What I was looking for is located almost as far back as you can get, on the driverís side a little further back than the indent from the gas tubes. It's a black plastic plug that can be popped up (or down) with a screwdriver. Now you can run the wires through this hole down and out to the hitch where they will hang. If you are cool (like me) I cut a slit in the middle on the black plug, cut off the 4-pin connecter (leaving room to splice it again) (thereís more reason for this later) then push the wires through the slit. It looks way better and the plug is still plugging the hole. You can splice the 4-pin now (or not).
If you are satisfied with this then good; reassemble everything. I however, was/am not. I have 5000 lb hitch with a V8. If I wanted to tow a MAX of 2000 lbs I would have gotten a hitch for my V6 impala. However, if you stick with the 4-pin you can only tow a MAX (yes, a MAX) of 2000 lbs. It doesn't matter what size your engine is. Trailers towing more than 2000 lbs have to have their own brakes, which means a break controller, which means more wires and more work, but totally worth it.
Once again I hit up eBay. Although I was a little disappointed that, although I bought a hitch for 5000 lbs, I only got the stuff to tow 2000. I was able to get a mediocre brake controller for $25. The higher end ones run about $80 or so. I was also able to buy a 7-pin socket plug for $20. You will also need about 20Ft of blue wire, 20ft red, some black, and some purple (all 14 gauges). You will need some 10 gauge red and 10 gauge black. About 10 ft each. While youíre at it, get some butt connectors (10 gauge through 16 gauge blue/yellow colored) some ring terminal connectors, 2 20 Amp auto-reset circuit breakers and some 3/16 and 1/4 inch heat shrink tubing.
Letís start with the easy stuff. My hitch has a slot for me to mount the 7-pin socket next to the hitch. Thatís where I mounted it with 4 screws and 4 nuts. From what I read you could petty much mount it wherever though. The socket will have 7 wires/places to put the wires.
We'll start with the simple wiring first. Since the 4-pin has already been cut off, strip about 1cm on insulation off of each Brown, yellow, green and white wire. Do this for the other side too. Now take 1 of each color wire and crimp one butt connector to it. If one wire is 12 gauge use a yellow connector, if both wires are 14/16 gauge use a blue one. On the wire without the crimp, slide a heat shrink tube over it (use 3/16 for the blue connectors and 1/4 for the yellow). Now crimp the two corresponding wire colors together (yellow goes with yellow). Slide the heat shrink over the connector and shrink it with a lighter/heat. Do this for the other 3 wires. Pretty simple and looks professionally done.
This is where it gets harder. I'll start with what I KNOW. Take off the bottom trim on the driverís side door area. It is on with clips. Then remove the 3 screws and one clip holding the kick panel on. Remove the kick panel. I'm assuming everything previously removed is still off. If you look closely you should see a bundle of wires running under/near these trim panels that goes all the way to the back. Now take the Red and Blue 14 gauge wires and run them from the front to the back following the other wires so that they will be hidden when the trim goes back on. You shouldn't have to remove the driver's seatbelt panel because you can just tuck the wires under it. Now push these wires through the black plug and out to the hitch. Now follow the same procedure with the other wires, but these will probably be 12 gauge. The blue wire obviously connects to the blue wire on the socket (this is for the breaks). However, the RED wire will connect to the BLACK wire on the socket (This is the +12V wire).
This is where things get a little foggy.... So far everything I've read says to splice the purple wire (reverse lights) into the reverse lights on the tail light (In case your reading this AND know what youíre doing, PLEASE inform me if this is wrong, I don't think it is. The other option is to run a purple wire with the RED and BLUE ones to where the reverse light output is under the dash). In this case it is pretty easy because the tail light is directly above the black plastic plug. Splice into the purple/blacks-stripe (it might be different for you) wire. Run a purple (It can really be any color) from the splice, down through the plug and to the socket. Do like the other wires, it splices into the purple wire on the socket.
All 7 of the wires have now been connected to the socket. What you should do now is to take some zip ties and tie the wires together about 7inch lengths. If possible make them pretty taught and attach them to the frame. Once back in the cargo area, zip tie the wires to the other wires to keep them secure. Reinstall the black plastic plug with the wires running through it. The passenger door trim and cargo trim pieces can now be re-attached and secured because all the wire has been run. Donít forget the black square insulation thing over the tow hookup. It should look pretty clean with no wires showing.
Once again it gets a little foggier now. It is time to install the brake controller. The brake controller should be mounted somewhere by the driver's knees, off to the left or right on the plastic panel. Once you've decided where to mount the controller, remove the panel. Its got 2 screws on top, one screw on the side and 2 bolts (10mm) on the bottom. The brake controller has 4 wires on it. The black is the +12V in, White is ground, Red is Brake switch input, and blue is brake Output. We will need to run most of them.
Letís start with the +12V and ground. Run the 10 gauge black and red wires out through the firewall. There is a hole where some other wires are running and you should be able to force the red and black through. You will need to run them through the engine compartment. Keep them off to the side away from any moving parts using the zip ties to frequently secure them in place. Leave the wires by the battery without hooking them up yet. On the other end, cut off a piece about 3 inches long of the Red 10 Gauge wire. Strip 1 cm of insulation off each end of the red wire (3 total, each side of the 3in piece and the end of the engine wire). Each end of the wire gets a ring terminal crimped onto it. Now connect the end of the long wire to the input side of an "auto reset" circuit breaker. Using the 3in piece of wire, connect the input side of that breaker, to the input of the Other "auto reset" circuit breaker.
It is now time to connect the +12V wires. There are two of them. The red wire that was run earlier to the hitch will attach to the output end of one of the circuit breakers using a crimp-on ring terminal. The BLACK wire on the Break Controller will connect to the output end of the second breaker via a crimp-on ring terminal.
This is probably the trickiest part of installing the break controller. The RED wire on the brake controller needs to be attached to the brake lamp output of the brake switch. The problem is that there is like 100 wires in that area, so which one is correct. For this specific 2000 Jeep grand Cherokee it is apparently a White wire with a Tan stripe. Looking at the break switch (located on the brake) it is the second furthest wire away from the brake. Attempt to Follow it further down the wire toward the kick panel. Somewhere between the kick panel and the brake switch, splice in a red 14 gauge wire. Attach this wire to the red wire one the brake controller.
Finally, splice the blue wire on the brake controller to the blue wire that was run to the hitch. Secure all the wires with zip ties so that they donít move. You could also put the heat shrink tubing on them but I donít think it matters.
Go back to the engine compartment and strip off the insulation of the black and red 10 gauge wires you ran earlier. Depending on what your terminals are like, you could crimp on a ring terminal to each wire then use the bolts on the original wires to connect them. All that really matters is that these wires are attached to the ones on the battery terminals.
Reconnect the battery. Assuming everything works; reassemble the dash, the door trim and kick panel and mount the brake controller. You can test everything using a 12v test light and attaching one end to ground connector of the 7-pin and then each individual connector while someone flips the indicators and puts it in reverse and all that jazz.
That is basically it. This process is Much simpler if your car/truck/suv is equipped with one of those quick connect ports. I hope this is useful in some way. Also if you notice something wrong with the information here, please tell me and I will definitely change it. Also if you have any questions Iím more than happy to answer them.