GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Holden 🢒 2005 🢒 Calais 🢒 DTC 🢒 DTC P0974

DTC P0974 V6

DTC Description

This diagnostic procedure supports DTC P0974 1-2 Shift Solenoid (SS) Control Circuit High Voltage.

Circuit Description

The 1-2 shift solenoid (SS) valve controls the fluid flow acting on the 1-2 and 3-4 shift valves. The solenoid is a normally-open exhaust valve with the 2-3 SS valve, the 1-2 SS valve allows four different shifting combinations. The solenoid attaches to the control valve body within the transmission. The 1-2 SS valve receives ignition voltage through the ignition 1 voltage circuit (circuit 339). The transmission control module (TCM) controls the solenoid by providing the ground path on the 1-2 SS valve control circuit (circuit 1222).

When the TCM detects a continuous short to voltage in the 1-2 shift solenoid valve control circuit, then DTC P0974 sets. DTC P0974 is a type A DTC.

Refer to Automatic Transmission Controls Schematics , Automatic Transmission Inline 20-Way Connector End View, Automatic Transmission Internal Connector End Views , Automatic Transmission Control Module Connector End Views , and Automatic Transmission Related Connector End Views to aid in diagnosis.

Conditions for Running the DTC
    • The system voltage is 8-18 V.
    • The engine speed is 500 RPM for 5 seconds.

Conditions for Setting the DTC

DTC P0974 sets if the TCM commands the solenoid on the voltage feedback remains high, battery voltage.

Action Taken When the DTC Sets
    • The TCM requests the ECM to illuminate the check powertrain icon during the second consecutive trip in which the Conditions for Setting the DTC are met.
    • The TCM commands maximum line pressure.
    • The TCM freezes transmission adaptive functions.
    • The TCM inhibits TCC engagement.
    • At the time of the first failure, the TCM records the operating conditions when the conditions for setting the DTC are met. The TCM stores this information as a Failure Record.
    • At the time of the second failure, the ECM records the operating conditions when the conditions for setting the DTC are met. The ECM stores this information as a Freeze Frame.
    • The TCM stores DTC P0974 in TCM history during the second consecutive trip in which the conditions for setting the DTC are met.

Conditions for Clearing the MIL/DTC
    • The ECM turns off the check powertrain icon after the fourth consecutive drive trip in which the TCM does not send a check powertrain icon illumination request.
    • Tech 2 can clear the DTC.
    • The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-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 following numbers refer to the step numbers in the diagnostic table:

2 Checks the ability of the TCM to command the 1-2 SS valve.

3 Checks for a short to voltage in the 1-2 SS signal circuit.

4 Checks the serviceability of the 1-2 SS and the control valve body wiring harness.

Step

Action

Yes

No

1

Has the Diagnostic System Check been performed?

Go to Step 2

Refer to Diagnostic System Check - Automatic Transmission

2
  1. Connect Tech 2 to the DLC.
  2. Turn on the ignition, with the engine off.

    3. Important: Before clearing the DTC, use the Tech 2 Freeze Frame/Failure Record in order to record the transmission parameters at the time the DTC set. Using Tech 2 to clear the DTC(s) erases the Freeze Frame/Failure Record records from the TCM.

  3. On Tech 2 select: Transmission / Automatic Transmission / Diagnostic Trouble Codes / Freeze Frame.
  4. Select the relevant DTC and note the parameters at the time of the DTC setting.
  5. On Tech 2 select: Diagnostic Trouble Codes / Clear Engine and Transmission DTCs.
  6. Follow the instructions on Tech 2 and clear the DTCs.
  7. On Tech 2 select: Transmission / Automatic Transmission / Miscellaneous Tests / Shift Solenoid A.
  8. With Tech 2 command the shift solenoid A ON and OFF.
  9. On Tech 2 select: Data Display / 1-2 Shift Data.

Does Tech 2 display the Shift Solenoid A Circuit as OK?

Check for an intermittent fault in the circuit, refer to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3
  1. Turn off the ignition.
  2. Disconnect connector X121-X1 from the transmission.

    3. Important: Additional DTCs may set

  3. Install Tool No. J 44152 Jumper Harness (20 pins) on to the harness connector X121-X1.
  4. Turn on the ignition, with the engine off.
  5. Using a test lamp, probe between connector X121-X1 pin A and a known ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 4

4
  1. Install Tool No. J 44152 on to the transmission connector X121-X1.
  2. Using a multimeter set to measure resistance, probe across transmission connector X121-X1 pins E and A.

Does the multimeter display less than 20 Ω?

Go to Step 5

Go to Step 7

5
  1. Remove Tool No. J 44152 from the transmission.
  2. Gain access to the 1-2 SS and the control valve body wiring harness, refer to Torque Converter Clutch Pulse Width Modulation Solenoid, Torque Converter Clutch Solenoid, and Wiring Harness.
  3. Disconnect the internal connector from the 1-2 SS.
  4. Using a multimeter set to measure resistance, probe across the 1-2 SS pins.

Does the multimeter display less than 20 Ω?

Replace the 1-2 SS, refer to Torque Converter Clutch Pulse Width Modulation Solenoid, Torque Converter Clutch Solenoid, and Wiring Harness

Go To Step 8

Replace the control valve body wiring harness, refer to Torque Converter Clutch Pulse Width Modulation Solenoid, Torque Converter Clutch Solenoid, and Wiring Harness

Go to Step 8

6

Using a multimeter, test circuit 1222 for a short to voltage.

Did you find and correct the condition?

Go to Step 8

Go to Step 7

7

Replace the TCM, refer to Transmission Control Module Replacement

Did you complete the replacement?

Go to Step 8

--

8

Perform the following procedure in order to verify the repair:

  1. On Tech 2 Select: Diagnostic Trouble Codes / Clear Engine and Transmission DTCs.
  2. Follow the instructions on Tech 2 and clear any DTCs.
  3. On Tech 2 select: Data Display / 1-2 Shift Data.
  4. Drive the vehicle in D4 and ensure the following conditions are met:
    5. • The TCM commands the Shift Solenoid A On and the Shift Solenoid A Circuit status parameter displays Okay.
    • The TCM commands the Shift Solenoid A Off and the Shift Solenoid A Circuit status parameter displays Okay.
    • All conditions are met for 5 seconds.
  5. On Tech 2 select: Diagnostic Trouble Codes / Read DTC Information.

Has DTC P0974 set?

Go to Step 2

Go to Step 9

9

On Tech 2 select: Diagnostic Trouble Codes / Read DTC Information.

Does Tech 2 display any DTCs you have not diagnosed?

Refer to Scan Tool Data List

System OK

When all diagnosis and repairs are completed, check the system for correct operation.