P0971

DTC P0971





Circuit Description
The shift pressure control (PC) solenoid valve regulates solenoid modulator fluid passing through the solenoid into shift control pressure. The transmission control module (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.

DTC Descriptor
This diagnostic procedure supports the following DTC:

DTC P0971 Shift Pressure Control (PC) Solenoid Control Circuit High Voltage

Conditions for Running the DTC
^ The engine speed is 400 RPM or greater.
^ The ignition voltage is 10.2 - 15.5 volts.
^ Trans. protection mode is OFF.

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 powertrain control module (PCM) to illuminate the malfunction indicator lamp (MIL).
^ The TCM turns the Trans. Protection Mode ON.
^ The transmission will operate in 4th gear when the transmission is shifted into D.
^ The line pressure is at maximum.
^ The torque converter clutch (TCC) is disabled.
^ The TCM freezes the transmission adaptive functions.
^ The TCM disables engine braking.
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM 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 PCM 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

Step 1 - Step 6:

Step 7 - Step 11:

The numbers below 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.