Action Taken When the DTC Sets

WARNING: This page is about a different car, the 2005 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.

The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
The TCM commands maximum line pressure.
The TCM freezes transmission adaptive functions.
The TCM commands High Side Driver 1 OFF.
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.