AF23-5 Automatic Transaxle

AF23-5 AUTOMATIC TRANSAXLE

DTC P0603
Circuit Description with AF23-5 Automatic Transaxle
A normal function of the transmission control module (TCM) is to perform an internal test that verifies the integrity of the non-volatile random access memory (NVRAM) allocation. This diagnostic detects faults in the allocation of NVRAM that contain the transmission adaptive pressure memory cells by comparing a calculated checksum with a stored checksum. When the TCM detects that the calculated checksum is different from the stored checksum, DTC P0603 sets. DTC P0603 is a type C DTC.

Conditions for Running The DTC
The ignition is ON.

Conditions for Setting The DTC
The TCM NVRAM checksums do not match.

Action Taken When the DTC Sets
^ The TCM requests the DIC to display the SERVICE VEHICLE message.
^ The TCM turns the Trans. Protection Mode ON. When the Trans. Protection Mode is ON, the following conditions occur:
- The transmission will operate in 5th gear when the transmission is shifted into D or I range and 2nd gear when shifted into L range.
- The line pressure is at maximum.
- The torque converter clutch (TCC) is disabled.
- The TCM freezes the transmission adaptive functions.

^ The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame.
^ The TCM stores DTC P0603 in TCM history.

Conditions for Clearing the DIC/DTC
^ The TCM clears the SERVICE VEHICLE driver information center (DIC) message request, when the condition no longer exists.
^ A scan tool can clear the DIC/DTC.
^ The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The TCM cancels the default actions when the ignition is OFF long enough in order to power down the TCM.