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DTC P0601, P0602, P0603, or P0604

DTC P0601, P0602, P0603, or P0604

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

Control Module Read Only Memory Performance

DTC P0602

Control Module Not Programmed

DTC P0603

Control Module Long Term Memory Reset

DTC P0604

Control Module Random Access Memory Performance

Circuit/System Description

This is an internal fault detection of the transmission control module (TCM). This fault is handled inside the TCM and no external circuits are involved.

Conditions for Running the DTC

The TCM runs the program to detect an internal condition at key ON. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

Conditions for Setting the DTC

P0601

The read only memory (ROM) test has failed 5 or more times.

P0602

The TCM has been unable to detected the start program.

P0603

The TCM has detected a memory checksum error.

P0604

The TCM random access memory (RAM) test has failed 5 or more times.

Action Taken When the DTC Sets


P0601, P0602, P0603, P0604

• DTCs P0601, P0603, P0604 are Type A DTCs.

• The TCM commands maximum line pressure.

• The TCM forces the torque converter clutch (TCC) OFF.

• The TCM inhibits TCC engagement.

• The TCM freezes transmission adaptive functions.

• The TCM commands an immediate landing to 2nd gear.


Conditions for Clearing the DTC

DTCs P0601, P0602, P0603, P0604 are Type A DTCs.

Reference Information

Description and Operation

Transmission Component and System Description

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification


1. Engine running. Let the engine run for at least 1 min.

2. Ignition OFF for at least 30 s to allow for the complete shutdown of the TCM.

3. Ignition ON, verify that DTC P0602 is not set.

4. If the DTC is set, program the TCM. If the DTC resets, replace the TCM.

5. Check the DTC Info with a scan tool. Diagnostic trouble codes P0601, P0603 and P0604 must not be activated.

6. If a DTC sets, replace the TCM.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Refer to Control Module References for TCM replacement, setup, and programming.

• Perform the Transmission Adaptive Functions .