P1621

DTC P0601, P0602, P0603, P0604, or P1621

Diagnostic Instructions

* Perform theDiagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* ReviewStrategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) 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

Component Connector End Views (Connector Views)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information
DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (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 theControl Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and Transmission Control Module Assembly Inspection) .


Repair Instructions

Perform theDiagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.


Perform theService Fast Learn Adapts (Programming and Relearning) .