P1644

P1644-INCORRECT VARIANT/CON FIG U RATION





Theory of Operation
The Transmission Control Module (TCM) performs various internal tests to verify proper controller operation. If the TCM detects that the variables that dictate the vehicle application are not present, the controller will enter Limp-in mode and illuminate the MIL.
- When Monitored:
Continuously with the ignition on.
- Set Condition:
If the TCM detects that the variables that dictate the vehicle application are not present.

Possible Causes
- CONTROLLER NOT CODED
- TRANSMISSION CONTROL MODULE

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. NAG1 Automatic Transmission

Diagnostic Test
1. PERFORM TCM REPLACEMENT PROCEDURE

NOTE: Controller is programmed with generic software and will not allow the correct vehicle Powertrain management.

With the scan tool, perform the TCM replacement procedure.
Were you able to update the controller successfully?
YES >>Test Complete.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. NAG1 Transmission Verification Test
NO >>Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. NAG1 Transmission Verification Test