Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2006TAHOE 4WD V8-5.3L VIN TREPAIR AND DIAGNOSISTRANSMISSION AND DRIVETRAINAUTOMATIC TRANSMISSION/TRANSAXLECONTROL MODULETECHNICAL SERVICE BULLETINSENGINE, A/T CONTROLS - SHARED DIAGNOSTIC TROUBLE CODES
2006 Chevrolet Tahoe 4WD V8-5.3L VIN T
Engine, A/T Controls - Shared Diagnostic Trouble Codes
2006 Chevrolet Tahoe 4WD V8-5.3L VIN TSECTION Engine, A/T Controls - Shared Diagnostic Trouble Codes
Bulletin No.: 05-06-04-060
Date: September 23, 2005
INFORMATION
Subject:
Powertrain Control Module (PCM), Engine Control Module (ECM), Transmission Control Module (TCM) Diagnostic Trouble Code(s) (DTC)(s) P0601, P0602, P0603, P0604, P1621 Shared In Multiple Modules
Models:
2005-2006 GM Passenger Cars and Light Duty Trucks (including Saturn)
2005-2006 HUMMER H2
2006 HUMMER H3
2005-2006 Saab 9-7X
Beginning in 2005, some control modules (ECM's, TCM's) have specific codes that describe internal failures of the module. These DTCs are not module specific and can be found on any controller that has these codes.
Society of Automotive Engineers (SAE) J2012 committee has set these specific codes to be an industry standard of all manufacturers.
Currently, these common codes are:
^ P0601 - Control Module Read Only Memory (ROM)
^ P0601 - Transmission Control Module (TCM) Read Only Memory (ROM)
^ P0602 - Control Module Not Programmed
^ P0602 - Transmission Control Module (TCM) Not Programmed
^ P0603 - Control Module Long Term Memory Reset
^ P0603 - Transmission Control Module (TCM) Long Term Memory Reset
^ P0604 - Control Module Random Access Memory (RAM)
^ P0604 - Transmission Control Module (TCM) Random Access Memory (RAM)
^ P1621 - Control Module Long Term Memory Performance
^ P1621 - Transmission Control Module (TCM) Long Term Memory Performance
Important:
^ Use caution when diagnosing these shared codes to perform the appropriate diagnostic procedure on the appropriate module.
^ A low voltage condition may set one or more of the above codes. Repair any low voltage conditions prior to diagnosing the above codes.
Refer to the appropriate Service Information (SI) document for Diagnosis and Repair procedures.

Disclaimer
Date: September 23, 2005
INFORMATION
Subject:
Powertrain Control Module (PCM), Engine Control Module (ECM), Transmission Control Module (TCM) Diagnostic Trouble Code(s) (DTC)(s) P0601, P0602, P0603, P0604, P1621 Shared In Multiple Modules
Models:
2005-2006 GM Passenger Cars and Light Duty Trucks (including Saturn)
2005-2006 HUMMER H2
2006 HUMMER H3
2005-2006 Saab 9-7X
Beginning in 2005, some control modules (ECM's, TCM's) have specific codes that describe internal failures of the module. These DTCs are not module specific and can be found on any controller that has these codes.
Society of Automotive Engineers (SAE) J2012 committee has set these specific codes to be an industry standard of all manufacturers.
Currently, these common codes are:
^ P0601 - Control Module Read Only Memory (ROM)
^ P0601 - Transmission Control Module (TCM) Read Only Memory (ROM)
^ P0602 - Control Module Not Programmed
^ P0602 - Transmission Control Module (TCM) Not Programmed
^ P0603 - Control Module Long Term Memory Reset
^ P0603 - Transmission Control Module (TCM) Long Term Memory Reset
^ P0604 - Control Module Random Access Memory (RAM)
^ P0604 - Transmission Control Module (TCM) Random Access Memory (RAM)
^ P1621 - Control Module Long Term Memory Performance
^ P1621 - Transmission Control Module (TCM) Long Term Memory Performance
Important:
^ Use caution when diagnosing these shared codes to perform the appropriate diagnostic procedure on the appropriate module.
^ A low voltage condition may set one or more of the above codes. Repair any low voltage conditions prior to diagnosing the above codes.
Refer to the appropriate Service Information (SI) document for Diagnosis and Repair procedures.
Disclaimer
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.