Buick Regal: DTC P0973 or P0974

Diagnostic Instructions

• Perform the Diagnostic System Check prior to using this diagnostic procedure: Refer to Diagnostic System Check - Vehicle
• Review the description of Strategy Based Diagnosis: refer to Strategy Based Diagnosis
• An overview of each diagnostic category can be found here: refer to Diagnostic Procedure Instructions

DTC Descriptor

DTC P0973

Shift Solenoid Valve 1 Control Circuit Low Voltage

DTC P0974

Shift Solenoid Valve 1 Control Circuit High Voltage

Diagnostic Fault Information

Typical Scan Tool Data

Shift Solenoid Valve 1

Shift Solenoid Valve 1 Control Circuit High Voltage Test Status

Shift Solenoid Valve 1 Control Circuit Low Voltage Test Status

Shift Solenoid Valve 1 Control Circuit Open Test Status

Circuit/System Description

Depending on the state of the pressure control solenoids, the position of the component Q32A will cause either a gear shift or 1st gear engine braking.

Conditions for Running the DTC

Ignition Voltage=9 to 32 V

Frequency the DTC runs=Continuously - After the running conditions are met - For 2 s

Conditions for Setting the DTC

Control Circuit=Commanded state does not match the actual state

Actions Taken When the DTC Sets

DTCs listed in the DTC Descriptor Category=Type A DTC

• Fail-Safe Mode=Active
• Learning=Disabled
• Transmission gear allowed=3rd Gear - After a stop

Conditions for Clearing the DTC

DTCs listed in the DTC Descriptor Category=Type A DTC

Reference Information

Schematic: Reference

Refer to Automatic Transmission Controls Wiring Schematics.

Connector End View: Reference

Refer to Component Connector End View Index

Component View: Reference

Refer to Disassembled Views.

Description and Operation

Refer to Transmission General Description.

Electrical Information: Reference

• Refer to Circuit Testing
• Refer to Connector Repairs
• Refer to Testing for Intermittent Conditions and Poor Connections
• Refer to Wiring Repairs

DTC Type: Reference

Refer to Powertrain Diagnostic Trouble Code (DTC) Type Definitions.

Scan Tool: Reference

Refer to Control Module: References.

Circuit/System Verification

1. Engine - Running.

2. Perform the scan tool control function:Shift Transmission Gear - Upshift & Downshift.

Verify the scan tool parameter:

• Shift Solenoid Valve 1 Control Circuit High Voltage Test Status=Not Run or OK
• Shift Solenoid Valve 1 Control Circuit Low Voltage Test Status=Not Run or OK
• Shift Solenoid Valve 1 Control Circuit Open Test Status=Not Run or OK
• If not the specified state

Refer to Circuit/System Testing

• Go to next step: If the specified state

3. Perform the scan tool control function:Shift Solenoid Valve 1 - Enable & Disable

Verify the component produces a clicking sound:Q32A Shift Solenoid Valve 1

• If the component does not produce a sound

Refer to Circuit/System Testing

• Go to next step: If the component produces a sound

4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Verify the DTC does not set.

• If the DTC sets

Refer to Circuit/System Testing

• Go to next step: If the DTC is not set

5. All OK.

Circuit/System Testing

1. Ignition/Vehicle - Off.

2. Remove the component:K71 Transmission Control Module.

NOTE: The component's temperature should be 19 to 21ºC (66 to 70ºF) while testing.

3. Test for 11 to 15 ohms between the test points:Control circuit terminal 23 X2 & Transmission Case

• If not between 11 and 15 ohms

1. Remove the component:Control Valve Body Cover
2. Disconnect the electrical connector:Q32A Shift Solenoid Valve 1
3. Test for less than 2 ohms between the test points:Control circuit terminal 1@Component harness & Terminal 23 X2@Control module harness
   • If greater than 2 ohms - Replace the component:Automatic Transmission Wiring Harness
   • If less than 2 ohms - Replace the component:Control Valve Body

• Go to next step: If between 11 and 15 ohms

4. Replace the component:K71 Transmission Control Module

Component Testing

1. Ignition/Vehicle - Off.

2. Disconnect the electrical connector:Q32A Shift Solenoid Valve 1.

NOTE: The component's temperature should be 19 to 21ºC (66 to 70ºF) while testing.

3. Test for 11 to 15 ohms between the test points:Control terminal 1 & Transmission Case

• If not between 11 and 15 ohms

Replace the component:Control Valve Body

• Go to next step: If between 11 and 15 ohms

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair: Refer to Diagnostic Repair Verification

• Refer to Control Valve Body Replacement
• Refer to Wiring Harness Wire Replacement
• For control module replacement, programming, and setup: Refer to Control Module: References

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