The CPS, Crank Position Sensor, is also called a CKS, Crank Sensor or CAS, Crank Angled Sensor to save it from getting confused with a Cam Position Sensor! No matter what people call it, it is still the same sensor. Its job is to tell the ECU the position of the crank in its rotation. Another function is that if the CPS detects no signal from the sensor but the ignition is turned on, it will assume something has happened like a car accident and shut off the fuel and spark for safety reasons. The problem is that when the sensor starts to fail, you get no spark or fuel so it will either not start, or suddenly without warning, stop the engine while it is running!
Preliminary testing:
Estimated Time: 30 minutes – 1 hour
Required tools
- 1/2″ open box wrench
- 3/8″ drive
- various 3/8″ extensions
- 3/8″ universal joint/swivel tip
- 3/8″ 11mm socket
- New CPS (Recommends OEM (whenever possible) or NAPA Premium)
- Wrenching beverage
Optional tools/items
- Flashlight
- Flathead screwdriver
- Needle nose pliers
DISCLAIMER: I am not responsible for anything you may do to your vehicle by following this guide. Following this tutorial is at your own discretion
Step 1
Make sure your vehicle is on flat ground with the emergency brake fully engage, and chock the wheels. I found that once you’re ready to work on your XJ start by selecting gear 1/2. This will position the linkage on the transmission so that you should be able to squeeze your arm up near the bell housing to hand thread the bolts when the time comes.
Pop the hood and grab your 1/2″ box wrench. I believe this should be a pretty standard size to remove the negative battery terminal. We want to make sure nothing is live while we’re working with sensitive electronics.
Step 2
Crawl up under the XJ with your crazy 3/8″ contraption and position yourself in a way you can see up into the transmission tunnel. You want to be looking at the 11 o’clock position (this is where a flashlight or worklight may come in hand). You should see a sensor that looks like this.
Your 3/8″ CPS contraption should be fairly easy to maneuver up into the channel in between the front DS and the actual trans.
You’ll want to start with the top 11mm bolt to prevent it possibly falling down into the bellhousing and be lost to Jeep purgatory. You’ll notice there is a little plastic flap which will hopefully help reduce the chances of this.Once you’ve removed the top bolt go ahead and remove the second lower bolt.
Congrats! You’re halfway done!
Step 3
Head back up topside and find where the CPS connects into the main harness. It should be right at the back of the intake manifold.
*Note: This image shows the pre 97+ connector style but location is identical.
Grab your needle nose pliers or flat head and pop the sensor’s female end out of the holding tab. Disconnect the old sensor and pop in the new one. Feed the new sensor down into the trans channel and crawl back under the vehicle.
Step 4
Install is pretty much the reverse of steps 1-2. Make sure you start with the bottom first so that you block off the hole into the bell housing! For some of you this may be the more challenging part if you have big ol’ meat hands and can’t reach up into the channel to hand thread the bolts. My best guess is you’ll have to be extra finesse to get the bolts started.
After it’s all said in done, reconnect the battery, hop back in the driver’s seat, don’t forget to put the XJ back in park and fire er’ up!
I’ve said that if I ever have to do this job again, I’m going to cut an access hole in the transmission tunnel. That thing is impossible to get to with man-sized arms and hands.