Allison 1000 & 2000 Gen 5 Fault Code:P0603 Internal Control Module Keep Alive Memory Error

CIRCUIT DESCRIPTION:
The Transmission Control Module (TCM) performs an internal memory self-test at power up that tests Flash Memory.

ACTION TAKEN WHEN THE DTC SETS:
1. The CHECK TRANS light illuminates.
2. Hydraulic Default. The transmission is restricted to Reverse, Neutral, and 3rd range.

CONDITIONS FOR CLEARING THE DTC:
Replace TCM.

DIAGNOSTIC AIDS:
Replace TCM.