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  • reset computer

    How do I reset computer (PCM) on 99 TJ.

  • #2
    These are instructions on how to flash your Jeeps computer memory as if it were brand new. This allows the computer to re-learn the engines characteristics. This is more than just disconnecting the battery, this actually restores the original factory settings as from the showroom floor, and allows the computer to learn your driving style and also any changes done to the engine since purchased. (i.e. high flow air filters, exhaust, fuel system changes, ect). It also can sometimes cure minor "hic-ups" is older vehicles or if you bought the vehicle used and want it to learn your driving style.

    Disconnect the POSITIVE battery Terminal and touch it to ground for 30 seconds. (This is to discharge the PCM capacitors, which maintain the Adaptive Memory.
    Reconnect the Battery Cable
    Turn Ignition Switch to the “On” position but DO NOT start the engine
    Turn Headlight “On”
    Turn Headlights “Off”
    Turn Ignition Key “Off”

    That's it. For the next 500 miles/50 start up cycles, the computer is re-learning everything


    • #3
      would that work for an '03? or have they changed something


      • #4
        Originally posted by fourwheelin49r
        would that work for an '03? or have they changed something
        Not sure, but I don't know why not. May Not help anything, but it won't hurt either.

        This bit of info was received from a guy on JU that put a supercharger on his TJ and came from a Jeep engineer. He did it because he was having some fuel mixture problems after the install and this fixed it.

        MORE INFO


        • #5
          Is there any sign, code, etc. to let you know you have done it right?


          • #6
            What are you trying to reset? A trouble code? Disconecting the battery does nothing to an OBDII controlled computer. The only way to reset evreything in the computer is with OBD tool. If it's a code your trying to get rid of go to auto zone they'll do it for free. The quesiton you have to ask though is whats tripping the errors?


            • #7
              For Safety sake, always remove the negative battery terminal first. Then do the above. When complete, put the negative terminal back on last.