I have 1998 Jeep Cherokee Sport with a 4.0 liter 6, Automatic Trans, and Select-Trac transfer case. I currently have 117,000 miles on the Jeep and have been trying to diagnose the source of a problem causing the check engine light to come on. The vehicle starts and runs fine.
The trouble codes that are being stored are P1391, P0320, and P0340 which all relate to problems with the camshaft/crankshaft position sensors.
I have replaced both sensors (OEM parts) and swapped in another PCM module without any success. I have ohmed out the wiring from the sensor connectors to the PCM connections and did not find any shorts or opens. I used an oscilloscope and monitored both signals at the PCM connector while the vehicle was running and they appeared to be fine. Does anyone have any other suggestions to investigate or found a solution to a similar problem?

Thank you,
Tim.

 

its not the same code but worth a read
it my relate to your issue
https://www.cherokeeforum.com/showth...198#post146198

 

Thanks for the idea. I found today that the wiring harness that goes up behind the fuel rail had a wire rubbing. I could tell the insulation was worn but I could not tell for sure if it had worn enough to allow the wire to gound out to the fuel rail. I taped the wire up until the weather gets a little warmer and reset the Check Engine Light. I'll let you know how I make out.

 

Hi, my fathers grand cherokee 1998
does not turn on.
i scan it and say po320 code
This is theoscilloscope image of the crankshaft sensor

 

Link below to a thread with more on the crank sensor, including how to test it, which is always recommended if it is suspect. Without the crank sensor making it to the computer, you will not have spark and you will not have fuel going TO the fuel injectors.

http://www.jeepforum.com/forum/f11/c...ailing-639123/

 

i can´t register in jeepforum.com

 

We can't help you with that. But you should still be able to read the thread in the link I provided.

 

Timsandri I am having the same issues you are same vehicle as well only mine has 100k more and it jolts randomly traveling at 50+. What did you find as your resolution?
Thanks
FF63