Allison 3000 & 4000 Gen 4 Fault Code: P0604 Internal Control Module Random Access Memory (RAM) Error

Description

DIAGNOSTIC RESPONSE:
Use default sump temperature

CIRCUIT DESCRIPTION:
The Transmission Control Module (TCM) performs an internal memory self-test at power up that writes and reads patterns at specific RAM locations to verify that all addresses and data lines are functioning correctly.

CONDITIONS FOR RUNNING THE DTC:
TCM software level January 2011 or higher.

CONDITIONS FOR SETTING THE DTC:
DTC P0604 sets if the TCM determines the TCM memory pattern that was written is not what was read from TCM memory during the self- test.

ACTION TAKEN WHEN THE DTC SETS:
1. The CHECK TRANS light illuminates.
2. DTC is stored in the TCM history on next key cycle.
3. All-segments symbol illuminates in both shift selector displays.
4. The TCM returns to the boot program.
5. The TCM inhibits shifts to range.

CONDITIONS FOR CLEARING THE DTC:
Replace TCM.

DIAGNOSTIC AIDS:
Replace TCM.