P0604 - Internal Control Module RAM

For a complete wiring diagram, refer to appropriate Wiring Diagram.

Theory Of Operation 

After the controller is reset, the microprocessor checks the integrity of each RAM location by writing to it and reading back from it. The read value should be the same as the written value. The MIL will illuminate and the transmission will be placed into limp-in after 10 seconds of problem identification.

• >>When Monitored:<< One time after the ignition switch is turned to the run position.
• >>Set Condition:<< The read value does not match the written value in any RAM location.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to TRANSMISSION PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Test Step 1 - PCM - Internal Error 

If there are no possible causes remaining, view repair.

Repair

• Using the schematics as a guide, check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. Check for Service Information Tune-ups or Service Bulletins for any possible causes that may apply. If no problems are found, replace and program the PCM per the Service Information. With the scan tool, perform QUICK LEARN. Refer to FOR ENGINE CJRA - REMOVAL AND INSTALLATION , FOR ENGINE CGVA - REMOVAL AND INSTALLATION or FOR ENGINE CGUA - REMOVAL AND INSTALLATION .
• Perform the Transmission Verification Test. Refer to TRANSMISSION VERIFICATION TEST .