Circuit Description
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 below refer to the step numbers on the diagnostic table.
-
This step verifies the ability of the TCM to command the shift PC solenoid valve.
-
This step verifies that the automatic transmission wiring harness and the shift PC solenoid valve have correct resistance.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics Connector End View Reference: Automatic Transmission Inline Harness Connector End View | ||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls - 2.2L (L61) | ||||
Important:
Does the Shift PC Sol. Actual Current reading vary from the Shift PC Sol. Ref. Current reading by more than the specified amount? | 0.10 amps | Go to Step 3 | Go to Intermittent Conditions in Engine Controls - 2.2L (L61) | |||||
Is the resistance less than the specified value? | 3.8 ohms | Go to Step 4 | Go to Step 5 | |||||
4 | Test the high control circuit (CKT 2880) of the shift PC solenoid valve and the low control circuit (CKT 5508) of the shift PC solenoid valve for being shorted together between the AT inline 14-way connector and the PC solenoid. Refer to Circuit Testing in Wiring Systems. Did you find the condition? | -- | Go to Step 8 | Go to Step 9 | ||||
5 | Measure the resistance between terminal 2 and all other terminals, except terminal 9, of the transmission side of the AT inline 14-way connector. Refer to Circuit Testing in Wiring Systems. Is the resistance between terminal 2 and any other terminal, except terminal 9, less than the specified value? | 100 ohms | Go to Step 8 | Go to Step 6 | ||||
6 | Test the high control circuit (CKT 2880) and the low control circuit (CKT 5508) of the shift PC solenoid valve for a short to voltage or a short together between the AT inline 14-way connector and the TCM. Refer to Circuit Testing in Wiring Systems and Wiring Repairs. Did you find a condition? | -- | Go to Step 7 | Go to Step 10 | ||||
7 | Repair or replace the wiring harness. Refer to Wiring Repairs in Wiring Systems. Did you complete the replacement? | -- | Go to Step 11 | -- | ||||
8 | Repair or replace the internal automatic transmission wiring harness assembly (33). Refer to Wiring Harness Removal and Wiring Repairs in Wiring Systems. Did you complete the replacement? | -- | Go to Step 11 | -- | ||||
9 | Replace the control valve body assembly (39). Refer to Control Valve Body Replacement . Is the replacement complete? | -- | Go to Step 11 | -- | ||||
10 | Replace the TCM. Refer to Transmission Control Module Replacement . Is the replacement complete? | -- | Go to Step 11 | -- | ||||
11 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 12 | Go to Step 2 | ||||
12 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List in Engine Conrols - 2.2L (L61) | System OK | ||||
