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4.0 Crankshaft Position Sensor Replacement


fredjacksonsan
06-15-2006, 10:13 PM
Since the longevity of the CPS is an issue on the 4.0 - and since it's likely to stay that way - I thought I'd post my experience in replacing the CPS on my 2000 Grand Cherokee. There may be a few differences between the vehicles, but the engine/powertrains are very close if not identical. If anyone else has any tips or observations, your input will be appreciated.

I had the classic symptoms: occasional rough running, died on the highway (more than once), started right back up, occasional odd shifting pattern. Oh yeah, and the P0320 code was a dead giveaway. :icon16:

(For the cliff notes, move down)

Time: about 2:30
Beers: 3
Cuss words: forget
Cuss words directed at engineers: about 5
Tools: flashlight, 10 mm socket, 7/16" socket, 2' of extensions (2x6" and 1 12"), swivel, and blade screwdriver (and of course 3/8" driver)

So starting out, the toughest thing was to spot where I'd be working. From posts here, I knew that the sensor was on the bell housing at the 11 o'clock position when viewed from the driver's seat. Even though it was bright and sunny out, damned if I could find it. Beer #1 while I got the flashlight and took a good look. A-ha moment, spotted the wiring harness going towards the sensor first. (D-C said it was hooked from just behind the intake manifold, but mine came from the opposite, passenger, side of the engine, down below the valve cover a bit).

Followed the cable over, and almost out of sight spotted the sensor's location. Didn't look right though, until I took a look from the bottom. There, I spotted it - again, almost out of sight, right where it was supposed to be. From below, I could see there was some sort of bracket, or shield, that I'll call the widget. It looked like it was there to guide the wires around to the opposite side of the engine. Found a good spot to put the 4-cell flashlight, front end wedged between the front driveshaft and the body, the tail resting on the transmission mount....almost perfect alignment to see the sensor from below. Once you're underneath you'll see the positioning works(not sure about Cherokee).

So, plan of action. From looking at it, would need to remove the single bolt from below, but couldn't reach my hand up in there no matter how I worked it. So would have to put bolt back from above. Removed the air intake with the 10mm and screwdriver from where it attached to the throttle body in order to have a clear shot from above. Now could easily visualize the sensor from under the hood, though it was very tight between the fuel rail and the firewall.

Crawled under, got the extensions hooked up and although it was fairly easy to get to the bolt, watch the fuel line that runs right next to it - it'll be in the way for most of the job but you can work around it. Bolt came out no problem. (Plan on dropping the bolt/widget combination.) You'll want the swivel just before the socket. The bolt on mine was 7/16".

Up above, detached the electrical connections. Again a tight fit for the hands, but manageable with a little help from Mr. Screwdriver. It was about here that I stopped cursing the engineers for the tight fit, since it was obvious that if the engine was out of the vehicle (like, at the factory) this would be less than a 5 minute job. There's also one of those plastic pressed clips supporting/holding the sensor leads onto the wiring harness which had to be detached.

At first I thought it would be a pain to thread the wires behind the back end of the block, but you can easily pass them over and behind/above the back of the valve cover. Start from the driver side and work your way over. I figured this out while removing the old sensor.

OK, beer #2. Removing the sensor was easy, just had to wedge my hand in there and work it out. It sticks pretty far into the bell housing. NOTE: I'm 6'4" and had a tough time reaching all the way back there from the front, until I got something set up in front of the Jeep to stand on. Then I could reach and I was almost laying on the engine to make it there. Some might have better luck from the side. I ended up using my left hand while standing on right foot.

Putting the new sensor in wasn't tough(it actually sticks pretty far in), and neither was snaking the wiring around the back side of the engine to reach the connection to the wiring harness. Pushed the sensor in most of the way.

Now, had to get the bolt in. With the widget, tried several times, both from above and below, to get the combo put back in. Tried widget by itself and with the bolt inserted. No luck. Remember I said to plan to drop the widget/bolt combination? Well, I followed the plan - 3 times. Keep in mind that the gray bolt is exactly the same color as the rocks in most driveways, and that there's a perfect space for them to fall onto - on top of the left front corner of the transmission, and you'll probably save some time when you drop them. :angryfire

Anyway, after searching for dropped parts, twice, and starting beer #3, finally decided to not reinstall the widget. The sensor is in a protected place, so figured it would be ok. Once the widget was out of the plan, easy enough to get the mounting bolt back in. ( Edit: Insert good advice to use a little grease to hold the bolt and widget together while reinserting) Held it between index and middle finger and got it in. Tried both from top and bottom (from bottom with socket); suggest from top unless you have some sort of special socket to hang onto it while you get it in. D-C's directions say to finger tighten, push the sensor in against the flywheel, then tighten up. Easy enough.

Crawled underneath, put the socket to the bolt and tightened well. The directions say 7N-m, or 60 in.lbs.....I figured good and tight but not too tight would be the correct amount. (Also compared tightening torque to what I'd used to remove it and made it about the same)

Compared to fighting with the widget, hooking up the electrical connections was child's play. Made sure all connections were made, including the clip.

One final check for tools under the hood, made sure my hand was (mostly) non grimed, reached in and turned it over. (Please run) Chir-chir-chir la la la la la....

:biggrin:

So after that, cleaned up, showered, opened beer #4. Job done. Wait, one more thing: post up to AF to help out!


Cliff notes:

Remove intake from throttle body.
Use flashlight to visualize from above & below, 11 o'clock from driver's perspective.
Need extensions to reach bolt, remove from below.
Electrical connections may not be where specified in instructions.
Long reach to sensor from above, need something to stand on.
Reaching to sensor with hand blocked from below.
Installing with widget a pain.



Hopefully this will help out for everyone that's going to be doing this repair. Questions welcome.

crys36
06-16-2006, 05:09 AM
did mine in what seems like half the time U had on my 2000 cherokee. Used some as we call it DumDum (black gooey stuff we use to seal windows in a tape form) to hold the bolts in the bracket while i was putting it up . It all go's pretty smooth with long extensions from the back. I used to do tranny's so I had me a 4 footer. When taking down the sensor make sure to use dielectric grease for the electrical couplings -they are suppose to be waterproff ( YEA) but found alot of green crap in there so cleaned it out with a toothbrush and some electrical cleaning spray. Filled it up with the elec grease since 1 connection is under by the tranny (Gee water gets there pretty easy). There are a couple of good posts on how to do this but just a few right tools and U should have minimal problems. The CPS when it starts going bad also controls the Start of the fuel pump !!!

spedman
07-15-2006, 02:11 AM
Replacing the CPS the simple way.:grinyes:
1 Disconnect the battery, unplug the CPS and tape a peice of wire or string to the pug "Going to the OLD CPS.
2 Block both rear weels.
3 Shift Jeep into Neutral.
4 Jack front of the Jeep up "Just to the PASSENGER side on the Diff".
5 Place a jack stand under each axel tube.
6 Lower jack and place it under the cross member for the Trany and raise into place to hold the wheight of the Trany "DO NOT LIFT IT!! :nono:".
7 Remove the 4 nuts and the 2 U bolts holding the front drive shaft to the FRONT Diff at the U joint.
8 Remove the 2 bolts and the 2 nuts holding the cross member in place and lower the jack down far enough to get your hands up there to replace it
" WACTH THAT YOU DON'T LOWER IT DOWN TOO FAR, WILL YOU CRUSH SOMETHING BETWEEN THE ENGINE AND THE FIREWALL :banghead: :crying:".
9 Pull the wire down on the old CPS and cut the tape off the plug on the old CPS and retape the wire or string to the new one and pull it back up.
10 Bolt the new CPS in place and reverse from number 8 to 1 and your done:rofl:

fredjacksonsan
07-15-2006, 07:50 AM
Why on earth would you remove the axle to replace a sensor that can be reached?

I've heard of the string trick, though.

spedman
07-15-2006, 03:03 PM
Why on earth would you remove the axle to replace a sensor that can be reached?

I've heard of the string trick, though.

Lower the FRONT DRIVE SHAFT, doing this gives you more room. Unless you can bend you arm between your rist and elbow.:p

fredjacksonsan
07-16-2006, 07:31 AM
Lower the FRONT DRIVE SHAFT, doing this gives you more room. Unless you can bend you arm between your rist and elbow.:p

Check....thanks...didn't read your post thoroughly enough --

peachie
09-04-2006, 04:28 PM
I have a '95 Cherokee 4.0 with an automatic tran. It ran out of gas and I have been unable to start it. I have been told it is probably the CPS. How does one check that out? I have also been reading about how to replace the CPS and am a bit concerned - have read several posts stating that many parts need to be removed/loosened/etc. When I looked under the car I could see, what i think is the CPS, at the 11 o'clock position. It is held in by 2 bolts and is fairly accessable. I have two questions: Am looking at the right part and where does the wiring harness connect on top?

Dale Aeppli
09-13-2006, 12:32 PM
Hi, you're looking at the cps sensor, it's held in place with 2 bolts, and the wiring goes up to a bracket at the rear of the intake manifold. I use a 1/4 inch drive rachett, wobble extesnions and extensions. Some bolts are metric& some are standard heads. Hope this helps Dale
Disconnect batery.

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