6L80-E Automatic Transmission

DTC P0601-P0604 or P1621

DTC Descriptor
This diagnostic procedure supports the following DTCs:
^ DTC P0601 Transmission Control Module (TCM) Read Only Memory (ROM)
^ DTC P0602 Transmission Control Module (TCM) Not Programmed
^ DTC P0603 Transmission Control Module (TCM) Long Term Memory Reset
^ DTC P0604 Transmission Control Module (TCM) Random Access Memory (RAM)
^ DTC P1621 Transmission Control Module (TCM) Long Term Memory Performance

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview

Circuit/System Description
This is an internal fault detection of the control solenoid (w/body and TCM) valve assembly. This fault is handled inside the control solenoid (w/body and TCM) valve assembly and no external circuits are involved.

Conditions for Running the DTC
^ The control solenoid (w/body and TCM) valve assembly runs the program to detect an internal fault when the key is ON or the engine is running.
^ Ignition voltage is 8-18 volts.

Conditions for Setting the DTC
The control solenoid (w/body and TCM) valve assembly has detected an internal malfunction.

Action Taken When the DTC Sets
^ DTCs P0601, P0602, P0603, P0604, and P1621 are Type A DTCs.
^ The TCM shifts to a default gear, shuts down, and turns OFF.

Conditions for Clearing the DTC
DTCs P0601, P0602, P0603, P0604, and P1621 are Type A DTCs.

Diagnostic Aids
When attempting to set TCM internal DTCs let the engine run for at least 1 minute and then shut the engine off for 30 seconds. Following this procedure will allow for a complete TCM shutdown. Reprogram the TCM and retest the DTC to see if the DTC resets.

Reference Information

Schematic Reference

Connector End View Reference
^ Automatic Transmission Inline 16-Way Connector End View
^ Automatic Transmission Internal Connector End Views

DTC Type Reference
^ Diagnostic Trouble Code (DTC) Type Definitions
^ Diagnostic Trouble Code (DTC) List/Type

Electrical Information Reference
^ Circuit Testing
^ Connector Repairs
^ Testing for Intermittent Conditions and Poor Connections
^ Wiring Repairs

Circuit/System Verification
1. Start the Engine.
2. Let the Engine run for 1 minute, then shut the engine OFF for 30 seconds.
3. Retest for DTCs P0601, P0602, P0603, P0604, and P1621.

Circuit/System Testing
1. Reprogram the TCM and recheck for DTCs.
2. If the DTC resets, replace the control solenoid (w/body and TCM) valve assembly.

Component Testing
Perform the control solenoid (w/body and TCM) valve assembly inspection procedure.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests