P0604-INTERNAL CONTROL MODULE RAM

For a complete wiring diagram Refer to Section 8W.

Theory of Operation

After the controller is reset (ignition turned to the RUN position), the microprocessor checks the integrity of each RAM location by writing to it and reading back from it. The read value should be same as value written.

When Monitored:
One time after the controller is reset (ignition turned to the RUN position).
Set Condition:
Whenever the Powertrain Control Module (PCM) detects an internal controller problem.

Possible Causes

POWER OR GROUND CIRCUIT

POWERTRAIN CONTROL MODULE

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

Diagnostic Test

1. CHECK WIRING AND CONNECTORS FOR INTERMITTENT OPERATION

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.
Wiggle the wires while checking for shorted and open circuits.
Check for any Service Bulletins that may apply.

Were there any problems found?

Yes

Repair the power and/or ground circuits to the PCM and Transmission Control Relay or TIPM (if equipped) as necessary.

Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

Replace the PCM per the Service Information. With the scan tool, perform QUICK LEARN.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)