P0971

AF23-5 AUTOMATIC TRANSAXLE

DTC P0971

Test 1-5:

Test 6-12:

Circuit Description with AF23-5 Automatic Transaxle
The shift pressure control (PC) solenoid valve regulates solenoid modulator fluid passing through the solenoid into shift control pressure. The TCM uses a pulse width modulated signal in order to control the signal pressure. The TCM compares various inputs in order to determine the appropriate pressure for a given load. The TCM varies the current to the shift PC solenoid valve from 0.1 amps, for maximum line pressure to 1.1 amps, for minimum line pressure. An internal current monitor within the TCM provides feedback in order to determine actual shift PC solenoid valve current draw.

If the TCM detects a continuous short to voltage in the shift PC solenoid valve circuit, then DTC P0971 sets. DTC P0971 is a type A DTC.

Conditions for Running the DTC
The ignition voltage is 8-18 volts. Trans. Protection Mode is OFF. The engine is running.

Conditions for Setting the DTC
The shift PC solenoid valve feedback circuit indicates a continuous short to voltage for 2 seconds or greater.

Action Taken When the DTC Sets
^ The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
^ 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 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 a Failure Record.
^ The TCM stores DTC P0971 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 MIL when the condition no longer exists for 3 ignition cycles.
^ 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 is OFF long enough in order to power down the TCM.

Test Description
The numbers refer to the step numbers on the diagnostic table.
2. This step verifies the ability of the TCM to command the shift PC solenoid valve.
3. This step verifies that the automatic transmission wiring harness and the shift PC solenoid valve have correct resistance.