P1621

DTC P0601, P0602, P0603, P0604, or P1621

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.



DTC Descriptors
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




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

Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference

* Electrical Center Identification Views
* Component Connector End Views
* Splice Pack Connector End Views
* Inline Harness Connector End Views

Electrical Information Reference

* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs

Scan Tool Reference

* Scan Tool Output Controls (Scan Tool Output Controls)
* Scan Tool Data List (Scan Tool Data List)
* Scan Tool Data Definitions (Scan Tool Data Definitions)

DTC Type Reference

* Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
* Diagnostic Trouble Code (DTC) List/Type (Diagnostic Trouble Code Descriptions)



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

Reprogram the TCM and recheck for DTCs.

If the DTC resets, replace the control solenoid (w/body and TCM) valve assembly.



Component Testing

Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and Transmission Control Module Assembly Inspection) .


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


Perform the Service Fast Learn Adapts (Programming and Relearning) .