P1638

P1638-TCM INTERNAL-CAN 1 RAM PERFORMANCE





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Transmission Control Module (TCM) performs various internal tests to verify proper controller operation. This DTC indicates that there is an internal error with the controllers Random Access Memory (RAM) on the CAN controller 1 section of the microprocessor. If detected, the controller will enter Limp-in mode and illuminate the MIL.

- When Monitored:
Continuously with the ignition on.

- Set Condition:
If the TCM detects an internal error with the controllers Random Access Memory (RAM) on the CAN controller 1 section of the microprocessor.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.

TRANSMISSION CONTROL MODULE (TCM)

Repair

- 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 the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.