Replacing the PCM, or powertrain control module, in your Jeep, although not a common repair because PCM failure is infrequent, is not difficult. You will find the PCM on the firewall in the engine compartment. It is on the passenger side and looks like a silver box with three large electrical connectors coming from it. A few hand tools will do the job but you will be able to get the replacement PCM only from a Jeep dealer.
Disconnect the negative battery cable from the battery with a wrench or socket and ratchet. Isolate the cable end so that it cannot fall back against the battery.
Locate the powertrain control module or PCM on the firewall of the Jeep. Remove the three plastic covers from the 32-pin connectors on the face of the PCM. The covers snap onto the connectors and come off the same way.
Unplug the three 32-pin connectors from the PCM, being careful not to bend the pins or damage the plug. The connectors will pull straight out from the PCM but you may need to wiggle the connector a little as they are a tight fit.
Remove the three mounting bolts that anchor the PCM to the firewall of the Jeep with a socket and ratchet. Position the new PCM on the fire wall and use the mounting bolts from the old one to secure it. Tighten the bolts to 35 inch-pounds with a torque wrench.
Carefully install the three 32-pin connectors into the plugs on the face of the PCM. Install the connector caps by snapping them in place.
Reinstall the negative battery cable onto the battery and tighten the retaining bolt with a wrench or socket and ratchet. A DRB scan tool must be connected to the PCM after installation to set the vehicle identification number and the original mileage of the Jeep so the odometer will read correctly.
