Help...check engine light

[chriss20]

I have a 1996 Jeep Grand Cherokee that is due up for an inspection. The problem is that the check engine light is still on and an inspection cannot be done with it on. When Iran it through Chryslers computer, I recieved a message saying that P1391 was the issue which is the Crank/Cam Sensor(i cant remember which one) however I replaced both the Crank and Cam sesnors not two months ago. So i am in a catch-22 because i cant get an inspection with the check engine light on but there is nothing wrong with the car. Someone please help!!!!
Thanks, Chris

[citizen@large]

Grand Cherokee section is here-

http://www.automotiveforums.com/vbul...splay.php?f=29

This is just us regular ol' Cherokees here...

[rattler02]

Originally Posted by citizen@large

Grand Cherokee section is here-

http://www.automotiveforums.com/vbul...splay.php?f=29

This is just us regular ol' Cherokees here...

This IS the Grand Cherokee section

Disconnect the battery terminals and see if it will clear the code. If it does come back something is still wrong.

[chriss20]

I have disconnected the battery and let the codes reset..the enging light is off when i start the car but 30 seconds later it comes back on..I have tried resetting the codes by unplugging the battery, having chrysler reset it, and having my mechanic reset it and the check engine light turns off temporarily and comes back on within moments of starting the car up again... please help

[bringselpup]

Are they just clearing the CE light or looking to see what code is making it light up?

I'd want to see if it was still the P1391 or some new code.

If it is, where did those sensors come from? Are they OEM mopar or some other brand? Like O2 sensors some people seem to feel a mopar crank sensor is the only one to use.

[chriss20]

I used all mopar parts..codes cleared still coming up 1391

[Bob D.]

...there is nothing wrong with the car..

Code p1391 - Intermittent Loss of CMP or CKP.
Maybe nothing noticeable at this point, but the PCM is detecting a problem, and it's not going to get any better on its own.

Originally Posted by chriss20

I used all mopar parts..codes cleared still coming up 1391

Just because the parts are Mopar doesn't mean you can't get a bad one.
Why not just diagnose and replace the crank or camshaft sensor instead of chasing/erasing codes?

[msdz]

My suggestion also is try checking the sensor out to see if it bad. Maybe replacing it again, maybe try buying a after market brand or even going to a junkyard, you may end up with a good one. May be one wire that is not making a good connection or broke but allows it to run.

[chriss20]

the dilema is..if the cam/crank sensor were not working properly like the p1391 code suggests, then the car would be misfiring and stalling left and right. A defective cam/crank sensor would lead to improper ignition/ misfiring so therefore the problem is not with the crank/cam sensor

[chriss20]

Originally Posted by Bob D.

Code p1391 - Intermittent Loss of CMP or CKP.
Maybe nothing noticeable at this point, but the PCM is detecting a problem, and it's not going to get any better on its own.


Just because the parts are Mopar doesn't mean you can't get a bad one.
Why not just diagnose and replace the crank or camshaft sensor instead of chasing/erasing codes?

The mention of mopar parts was in response to the user that asked what brand i used

[Bob D.]

Originally Posted by chriss20

the dilema is..if the cam/crank sensor were not working properly like the p1391 code suggests, then the car would be misfiring and stalling left and right. A defective cam/crank sensor would lead to improper ignition/ misfiring so therefore the problem is not with the crank/cam sensor

An intermittent problem with the CMP or CKP may not cause any driveability problems, it only takes is a split second to set a trouble code.
You can spend hundreds trouble shooting it or replace the faulty sensor.
It's a no brainer.

[rattler02]

Originally Posted by Bob D.

An intermittent problem with the CMP or CKP may not cause any driveability problems, it only takes is a split second to set a trouble code.
You can spend hundreds trouble shooting it or replace the faulty sensor.
It's a no brainer.

X2 they are known to cause problems, it can do it once to show that it is "possibly" on it way out, and it may never do it again,( just call it a hiccup ). And it can also leave you stranded, try another one, if you got the part locally explain that it has not corrected the problem and they will most likely give you a replacement. Just because it is a Mopar part does not mean it is a "good" one.

Also check your connections. An intermittant electrical problem can be a sign of a bad connection ( and a real PITA to find the reason it did it )

[bringselpup]

The usual scenario it seems is that the victim/owner can't start the vehicle, they are just cranking away, and have no CE light or codes to pull.

And everyone tells them crank sensor.

So if chriss20 has a P1391 might this not point to cam sensor and all that's related? Connectors etc.

Up to and including the recently replaced one.

Just because he actually has a code.

[Z85MAN]

just a thought ...but ,have you tried switching out the pcu?

[spenser]

A shift cable out of adjustment will cause this code. Found out the hard way after replacing the sensor 3 times. Was talking to a old timer Jeep mechanic 30 plus years experince. Adjusted the cable POOF no more code