P0977
DTC P0977
Circuit Description
The 2-3 shift solenoid (SS) valve controls the transmission fluid pressure acting on the 1-2 and 2-3 shift valves to position the valves for the appropriate gear. The 2-3 SS valve is a normally open exhaust valve located on the lower control valve body. Ignition 1 voltage is supplied to the solenoid. The transmission control module (TCM) commands the solenoid ON or OFF by providing a ground path. When the 2-3 SS valve is commanded ON, the TCM senses low voltage. When the 2-3 SS valve is commanded OFF, the TCM senses high voltage.
If the TCM detects a continuous short to voltage in the 2-3 SS valve circuit, then DTC P0977 sets. DTC P0977 is a type A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0977 2-3 Shift Solenoid (SS) Control Circuit High Voltage
Conditions for Running the DTC
^ The engine run time is greater than 5 seconds.
^ The TCM commands the 2-3 SS valve ON.
Conditions for Setting the DTC
The TCM detects a short to voltage on the 2-3 SS valve circuit for 4.4 seconds.
Action Taken When the DTC Sets
^ The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL).
^ The TCM commands maximum line pressure.
^ The TCM inhibits 4th gear.
^ The TCM freezes 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 stores DTC P0977 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.
^ The TCM clears the DIC message when the condition no longer exists.
^ 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 DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. This step tests the TCM and the wiring to the transmission.
5. This step verifies that the circuit has the correct resistance.
