Question about 2003 Jeep Grand Cherokee

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Changed crank sensor and filter in fuel tank still didn't work

Per previous posts, my 2003 jeep cherokee sputters and loses rpms and speed and when going down to stop will just die but will start back up. Have changed fuel filter and screen in tank, crank sensor and drained fuel tank and cleaned. I am told by several mechanics it COULD be the PCM/main computer going out as when one mechanic had it hooked up to a 'flight recorder' and lost all communication. This started out sporadic and now seems to be happening quite frequently. Before going thru the expense of getting a new PCM, could this be the problem? This is getting very frustrating!

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  • connelt Jul 20, 2009

    There were not any trouble codes at all, when he had this hooked up he said that it lost all communication. It first started out going down the highway and started to sputter and RPM dropped down to 1 and speed to 40mph from 65 and then sputtered and would kick back in. Sense changing crank sensor it has started to die when while going slow or coming to a stop and mechanic also stated it did this to him on the highway.



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This is possible however, the conditions you are discribing are not totaly consistant with that diag. the conditions you are discribing are more consistant with a TPS(throttle possition sensor) being faulty. If you Jeep is higher in milage this is quite common. They do tend to get gummed up. Have your tech remove it & clean it or replace it first with a "known good part" & try that. If that isn't it you may also have a poor connection @ the PCM or the crank sensor. The fact that the tech is losing communication is interesting & if this is happening only when you come to a stop would suggest a poor wiring connection & could be fixxed if the PCM is replaced just by messing with the PCM connector, everyone would think the PCM was @ fault but realy all it was was a bad connection with the PCM.

Good luck, hope this helps.

Posted on Jul 20, 2009

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Was your mechanic able to pull any trouble codes when the "flight recorder" was connected?
Does the engine run good at highway speeds and bad at idle to off idle?
Let me know.

Posted on Jul 20, 2009

  • Bruce Bracey
    Bruce Bracey Jul 20, 2009

    It could be a couple of different things.

    First, if the PCM looses voltage to it all communication will stop. I would make certain all connections are secured and corrosion free in the PCM power supply circuits.

    Second, if the communication wire is open, shorted to ground or battery, PCM communication will stop.

    Third, a failed PCM.

    Make sure the first two are checked before replacing an expensive PCM.

    Good luck.




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