Buick Regal: DTC P0606, P177F, P2637, or P2638

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: Strategy Based Diagnosis
• An overview of each diagnostic category can be found here: Refer to Diagnostic Procedure Instructions

DTC Descriptor

DTC P0606

Control Module Processor Performance

DTC P177F

Detected Gear Incorrect

DTC P2637

Torque Increase Calculation Malfunction

DTC P2638

Breaking Torque Calculation Malfunction

Circuit/System Description

For an overview of the component/system, refer to Electronic Component Description

Conditions for Running the DTC

P0606Condition 1

Engine=Running - For greater than 10 min

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

Condition 2

K71 Transmission Control Module=During control module power down

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

P177F

DTC P0606 = Not set

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

P2637

Engine=Running

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

P2638

Ignition=On

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

Conditions for Setting the DTC

P0606Condition 1

K71 Transmission Control Module=Internal Malfunction

Condition 2

Pressure Control Solenoid Valve=Commanded state does not match the actual state

P177F

Commanded gear=Incorrect - Engine Overspeed

P2637

Requested Torque Signal=Greater than a predefined threshold - For greater than 1 s

P2638

Automatic Braking Torque=Greater than a predefined threshold

Actions Taken When the DTC Sets

DTCs listed in the DTC Descriptor Category=Type A DTC - Exceptions listed below

DTC P2637=Type B

One or more of the following may occur:

• K71 Transmission Control Module=Reset
• Transmission gear allowed=3rd Gear
• TCM Requested Torque=0 Nm (0 lb ft)

Conditions for Clearing the DTC

DTCs listed in the DTC Descriptor Category=Type A - Exceptions listed below

DTC P2637=Type B

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

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. Ignition - On / Vehicle - In Service Mode

2. Verify DTC P0606, P177F, P2637, P2638 is not set.

• If the DTC is set

1. Perform all necessary programming and setup procedures for the control module:K71 Transmission Control Module
2. Verify the DTC does not set.
   • If the DTC sets - Replace the component:K71 Transmission Control Module
   • Go to next step: If the DTC is not set
3. All OK.

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

3. All OK.

Repair Instructions

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

For control module replacement, programming, and setup: Refer to Control Module: References.

DTC P0657

Diagnostic Instructions

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

DTC Descriptor

DTC P0657

Actuator High Control Circuit Group 1

Circuit/System Description

For an overview of the component/system, refer to Electronic Component Description This diagnostic applies to microprocessor integrity conditions within the control module. This diagnostic also checks if the control module is not programmed, or is programmed incorrectly.

Conditions for Running the DTC

K71 Transmission Control Module=Communication Enabled

Conditions for Setting the DTC

K71 Transmission Control Module=Internal Malfunction

Actions Taken When the DTC Sets

DTCs listed in the DTC Descriptor Category=Type A DTC

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

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. Ignition - On / Vehicle - In Service Mode

2. Verify DTC P0657 is not set.

• If the DTC is set

1. Perform all necessary programming and setup procedures for the control module:K71 Transmission Control Module
2. Verify the DTC does not set.
   • If the DTC sets - Replace the component:K71 Transmission Control Module
   • Go to next step: If the DTC is not set
3. All OK.

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

Repair Instructions

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

For control module replacement, programming, and setup: Refer to Control Module: References

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