VT25-E Automatic Transmission

VT25-E AUTOMATIC TRANSMISSION

DTC P0603
Circuit Description with VT25-E Automatic Transmission
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 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 A DTC.

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0603 Transmission Control Module (TCM) Long Term Memory Reset

Conditions for Running The DTC
^ No TCM DTC P0604.
^ The engine is running.

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

Action Taken When the DTC Sets
^ The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
^ The TCM freezes all ratio control functions, including the ratio control motor and desired speed ratio.
^ The TCM discontinues use of the closed loop ratio control algorithm. This causes the speed ratio to be defaulted and possibly not accurate. The resulting open loop control may or may not provide optimum ratio performance.
^ The TCM commands maximum line pressure.
^ The TCM freezes main line pressure transmission adaptive functions.
^ The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records.
^ The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
^ The TCM stores DTC P0603 in TCM history.





Conditions for Clearing the MIL/DTC
^ The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
^ A scan tool can clear the MIL/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 switch is OFF long enough in order to power down the TCM.