Limp-In Mode
In the event of a complete transmission electrical failure, loss of power to the Transmission Control Module (TCM), the transmission enters default limp-in mode. When the TCM loses power, all solenoids are de-energized. Maximum pressure locks the transmission in fourth gear, and a Diagnostic Trouble Code (DTC) is stored in memory. If the vehicle is in a forward gear range when the fault occurs, the transmission defaults to fourth gear.
The limp-in function remains active until the DTC is repaired or a stored DTC is erased with an appropriate scan tool.