This is going to be a how to on replacing the crankshaft position sensor on the 4.0L motor in the Grand Cherokee. This is by no means the ONLY way or "correct" way to replace the sensor. This is only the way I changed the sensor. I also never had to get under the Jeep to accomplish the task.
* universal joint
* socket extension
* 10mm socket
* 11mm socket
* 10mm wrench
* needle nose pliers
* flathead screwdriver
I had to replace mine due to the Jeep not starting and throwing the P0320 code. Onto the good stuff (yes, the pictures were staged for this guide).....
* The first thing is to remove the air box so it's out of the way. This will make it easier to remove the sensor later. To remove the air box you need to first remove the 1 bolt holding it in place using a 10mm socket (see location below).
Then remove pull on the valve cover breather tube (see below, red circle on left). Wiggle it some while pulling and it comes right off. Next, loosen the pipe clamp that holds the box to the tube from the air filter (see below, red circle on right). Wiggle the tube while pulling away from the air box and it comes off easily.
Next you need to loosen the pipe clamp that holds the air box down onto the throttle body (see location below). Once that's loose, wiggle the box while pulling up and it will pop free from the throttle box. Place the box aside for later.
* Now I removed the bottom part of the dash. To do this I started by removing the plastic piece right below the gauges (see picture below, the piece my hand is on). This is easy to remove, just pull up and out on it and the clips release. Set piece aside.
Next I removed the very bottom plastic piece from the dash. It's held in place by two 10mm bolts on the bottom, 3 Phillips screws on the top and side, and 1 clip on the left half. The below pictures show the location of the 3 screws and 2 bolts (starting on left side and moving in a clockwise direction). Once the bolts/screws are removed, pull on the plastic and it comes out.
* Next is to remove the air vent that blows air on your feet. It's located just to the right of the plastic panel you just removed earlier (see below).
It's only held in place by one Philips screw that's hidden behind the vent (see pictures below, arrow points to location where screw was). Use a short screw driver to remove it. Then pull the vent out.
* Next it to remove the plate on the firewall that the shifter cable runs through. It's held in place by two 10mm nuts (see picture below, one nut is hidden just out of view). Remove those by using a 10mm socket on the bottom one and a 10mm wrench on the top one. Then use a screwdriver to gently pry the cover up over the studs. To get the plastic out of the way, pull it over the studs and then slide it down the cable out of the way.
If you look through that hole in the firewall, you'll see the crank position sensor and the one 11mm bolt that holds it in place. I forgot to take a picture before I removed the sensor, but this is what you should see. The red arrow shows where the 11mm bolt would be located. The yellow arrow shows the hole where sensor sticks into the bell housing.
* Now you need to remove the actual sensor. You'll notice from the picture above, the 11mm bolt isn't exactly centered on that hole. To get to it I used a 11mm socket, universal joint, and an extension (in that order). Plug that assembly through the hole, get it seated on the bolt, and take the bolt out. If you're lucky, the bolt will stay in the socket (if you think ahead, get a small magnet and put it in the socket to hold the bolt). If you're like me, the bolt will drop and fall on the ground.
Now that the bolt is out, all you have to do is pull the sensor out of the hold. This is where the fun happens. I got it out of the hole from where the air box was located, use the following two pictures for reference. The first picture is a zoomed out view for location reference (next picture zoom was in the location where I'm pointing). The second picture is zoomed in and the left arrow is where the bolt threads and the right arrow is the actual sensor.
So I reached down to that location and pulled up on the sensor. It popped right out of the hole. Then I gently pushed it back towards the hole in the firewall. Next I went back into the Jeep and took a pair of needle nose pliers to grab the sensor and pull the tab through the hole in the firewall. I didn't have any string, so I attached dental floss (see below).
Now I went to the passenger side of the engine and located the plug. The two pictures below show where the plug should be located (sorry, picture taken after I accidentally ripped the plug away from the wiring). This is set up like the two pictures above. The first is zoomed out and I'm pointing towards where the second one is taken. The second picture shows the location where the plug was attached.
Once you've located the plug (sorry for the bad pictures here), disconnect it by pushing the tab down and pulling. You'll notice that the sensor plug is attached to the wire loom because the plastic is taped to the loom. I pulled on it and it came free (I zip tied it back on later). Now pull on the wires gently and the sensor should come out with the string attached.
* Finally, you'll put the new sensor back in place. Cut the string off the old sensor and tie it to the new sensor. Plug the one end back into the wire loom. Then reach down and roughly route the sensor back the way it came. Make sure that the plug end is extended towards the back of the engine or the sensor won't reach the hole. Now go back inside the Jeep and gently pull on the string. You'll pull the new sensor back to the hole in the firewall. Remove the string and use needle nose pliers to push it towards the hole. Now simply reverse the process above and it'll be set.
The whole thing sounds easier than it really is. It's very aggravating and frustrating. But with some patience, it will all go together.