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

Circuit Description

The 1-2 shift solenoid (SS) valve is located in the control valve body of the transmission. The Transmission Control Module (TCM) selects the required gear by turning the appropriate shift solenoid on or off, enabling the transmission to shift. Refer to Shift Solenoid Valve State and Gear Ratio.

The TCM provides voltage to the solenoid through the High Side Driver 2 (HSD2). The TCM uses a second driver to control the solenoid ground circuit. The controlled ground driver reports feedback voltage to the TCM. When the TCM commands the 1-2 shift solenoid valve on, the voltage of the control circuit should be approximately 0 volts. When the TCM commands the 1-2 shift solenoid valve off, the voltage of the control circuit should be approximately system voltage.

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

Conditions for Running the DTC
    • Ignition voltage is between 8.0 and 18.0 volts.
    • Engine is running between 450 and 6,800 RPM for at least 5 seconds.
    • The HSD2 is commanded on.

Conditions for Setting the DTC

DTC P0974 sets when the TCM detects a short to voltage in the 1-2 shift solenoid valve circuit.

Action Taken When the DTC Sets
    • The TCM requests the Powertrain Interface Module (PIM) to illuminate the Check Powertrain Malfunction Indicator Lamp (MIL) in the instrument cluster during the second consecutive drive trip in which the 'Conditions for Setting the DTC' are met.
    • At the time of the first failure, the TCM records the operating conditions when the 'Conditions for Setting the DTC' have been met. The ECM 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' have been met. The ECM stores this information as a freeze frame.
    • The TCM turns off the pressure control solenoid (causing maximum line pressure).
    • The TCM freezes the transmission adaptive learning function.
    • The TCM inhibits 3-2 downshifts if the vehicle speed is less than 8 km/h.
    • The TCM stores DTC P0974 into TCM history.

Conditions for Clearing the MIL/DTC
    • Tech 2 can clear the DTC.
    • The TCM clears the DTC from its memory (history DTC) if the vehicle completes 40 warm-up cycles without a non-emission related DTC occurring.
    • The TCM cancels the default actions when the ignition is off long enough to power down the TCM.
    • The PIM turns off the Check Powertrain MIL after the sixth consecutive drive trip in which the TCM does not send a Check Powertrain MIL illumination request.

Step

Action

Values

Yes

No

Schematic Reference: Automatic Transmission Controls Schematics

For information on testing wiring faults, refer to Wiring Systems.

1

Has the Diagnostic System Check - Automatic Transmission been completed?

--

Go to Step 2

Go to Diagnostic System Check - Automatic Transmission

2
  1. Connect the Tech 2 to the DLC.
  2. Ignition ON, engine OFF.
  3. Clear DTCs.
  4. Using the Tech 2, command the 1-2 shift solenoid ON.

Does the solenoid operate?

--

Go to Step 10

Go to Step 3

3
  1. Ignition OFF.
  2. Disconnect transmission wiring harness connector X12-X1 from the transmission 20-way connector.
  3. Ignition ON, engine OFF.
  4. With a test light connected to ground, probe terminal X1-17 of transmission wiring harness connector X121-X1.

Does the test light illuminate?

--

Go to Step 4

Go to Step 6

4
  1. Ignition OFF.
  2. Using a digital ohmmeter, measure resistance between terminals X1-17 and X1-14 of the transmission 20-way connector, X121-X1a.

Is resistance reading within the specified value?

15.0-20.3 Ω

Go to Step 5

Go to Step 7

5
  1. Disconnect the transmission wiring harness connector A112-T68 from the TCM.
  2. Using a digital voltmeter, check the 1-2 solenoid valve control circuit 1222 for short to voltage condition between transmission wiring harness TCM connector X121-T68, terminal X1-30 and connector, X121-X1, terminal X1-14.

Does check indicate a short to voltage in the wiring?

--

Go to Step 9

Go to Step 8

6
  1. Ignition OFF.
  2. Disconnect the wiring harness connector, A112-T68, from the TCM.
  3. Using a digital ohmmeter, check the HSD2 circuit 1525 between transmission wiring harness TCM connector A112-T68, terminal X1-8 and the connector X121-X1, terminal X1-17 for an open circuit condition.

Did you find an open circuit condition?

--

Repair open in circuit 1525.

Go to Step 11

Go to Step 8

7
  1. Remove transmission fluid pan. Refer to Transmission Fluid Pan and Filter Assembly Removal.
  2. Inspect transmission internal wiring harness for any sign of damage.
  3. Using a digital volmeter, check the 1-2 shift solenoid wiring circuit between TCM 20-way connector, terminals 17 and 14 for a short to voltage condition.

Did you find a short to voltage condition?

--

Repair short to voltage condition in relevant circuit.

Go to Step 11

Go to Step 10

8

Replace TCM. Refer to Transmission Control Module Replacement.

Is the replacement complete?

--

Go to Step 11

--

9

Remove and replace transmission internal wiring harness. Refer to Transmission Internal Electrical Harness Replacement.

Is the replacement complete?

--

Go to Step 11

--

10

Remove and replace the 1-2 shift solenoid valve. Refer to 1-2 Shift Solenoid Valve Replacement.

Is the replacement complete?

--

Go to Step 11

--

11
  1. Perform the following operation to verify the repair:
    2. 1.1. Select DTC on the Tech 2.
    1.2. Select Clear info.
  2. Operate the vehicle in the Conditions for Running the DTC.

Has the test run and passed?

--

System OK

Go to Step 2

When all diagnosis and repairs are completed, clear all DTCs and verify correct operation