Grand Cherokee CPS Problem

[Ethan11]

I have a 94 Grand Cherokee Ltd 4.0. About a month ago while driving it just died but started right back up. This problem has gotten gradually worse in the fact that when it decides to die it takes longer and longer to start. It may go a few days with out doing it or it may do it 4 times a day. There is really no ryhme or reason. Sometimes I am able to get it started quicker if I let it sit in neutral for a few minutes. In reading the forms that have been posted it seems like it might be my crankshaft position sensor. Can anyone tell me if this might be the case? My fuel pump and relay were replaced last year if that helps identify the problem. Thanks in advance.

[Chrysler-Tech]

Has anyone put a scan tool on it? If there are no codes in the PCM and it reads "0 starts since reset" after it starts back, OR...if you can't communicate with the PCM during the no start condition, then you may have a PCM problem. Try tapping on the PCM case with a small hammer while cranking next time it won't start. A shorted sensor can do almost the same thing sometimes, but the no start condition usually remains until the short is resolved.

[fredjacksonsan]

Your symptoms sound exactly like mine just before I replaced my own CPS.

Putting a scan tool on it isn't a bad idea, but I'd bet on the CPS being the culprit.

[AlohaBra]

Ethan...I have moved your post to the "GRand" Cherokee section of this AF.

[dksob81]

I have not seen a stalling problem caused by a PCM in jeeps, but they are very common with the CPS. Now a NO START condition can be caused by either, but I would put my money on the CPS as being the culprit.

[gsc123]

Where is cps located?

[95zj-tilshedies]

Originally Posted by gsc123

Where is cps located?

CPS (Crankshaft Position Sensor) is located on top of the bellhousing, almost directly under the firewall. Depending on the year, engine and transmission, it is either connected by one or two bolts. Is also a real PITA to get to. I needed between 18 - 20 inches of wobbler extentions and "swivel" connector to get to mine. Once you figure out how to get it out, it is easy to replace.

BTW -- changing the CPS on my ZJ seems to fixed all of the symptoms listed above; it has been 3 weeks without a stall.

[fredjacksonsan]

Have a read:

http://www.automotiveforums.com/vbul...d.php?t=579517

Hopefully that will help answer your questions.

Happy motoring!

[gsc123]

If the CPS was faulty or not working, should a diagnostic read a code specifying this?

[fredjacksonsan]

Originally Posted by gsc123

If the CPS was faulty or not working, should a diagnostic read a code specifying this?

Yup P0320 should show up.

[gsc123]

I dont get any fault codes? is it something else?

[fredjacksonsan]

Chrysler-tech suggested a scan tool be put on it...many auto parts stores like Advance Auto will do so for free and that'd be my next step.