Buick Regal: DTC P0729-P0735, P076F, or P07D9

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 P0729

6th Gear Ratio Incorrect

DTC P0730

Gear Ratio Incorrect

DTC P0731

1st Gear Ratio Incorrect

DTC P0732

2nd Gear Ratio Incorrect

DTC P0733

3rd Gear Ratio Incorrect

DTC P0734

4th Gear Ratio Incorrect

DTC P0735

5th Gear Ratio Incorrect

DTC P076F

7th Gear Ratio Incorrect

DTC P07D9

8th Gear Ratio Incorrect

Circuit/System Description

The control module calculates gear ratio based on information from various transmission sensors and information obtained from other control modules. If the commanded gear ratio does not match the calculated gear ratio, a DTC sets.

Conditions for Running the DTC

• DTC P0711, P0712, P0713, P0742, P0717, P07BF, P07C0, P0722, P077C, P077D = Not set
• B14A Transmission Output Shaft Speed Sensor=Greater than 59 RPM
• K71 Transmission Control Module= Communication Enabled
• Ignition Voltage=9 to 32 V
• Transmission Fluid Temperature=Warmer than -20ºC (-4ºF)
• Transmission Range= Drive
• {P0729Condition 1}Transmission Gear=6th gear
• {P0729Condition 2}Transmission Gear=6th gear & Engine Torque=Greater than 59 Nm (44 lb ft)
• {P0730Condition 1}Transmission Gear=1st Gear & Engine Torque=Less than 0 Nm (0 lb ft)
• {P0730Condition 2}Transmission Gear=1st Gear & Engine Torque=Less than -20 Nm (-15 lb ft) or Greater than 29 Nm (21 lb ft)
• {P0730Condition 3}Transmission Gear=1st Gear & Engine Torque=Greater than 59 Nm (44 lb ft) & B14C
• Transmission Input Shaft Speed Sensor=Less than 6001 RPM {P0731}Transmission Gear=1st Gear & Engine Torque=Greater than 59 Nm (44 lb ft) & B14C Transmission
• Input Shaft Speed Sensor =Less than 6001 RPM
• {P0732Condition 1}Transmission Gear=2nd Gear
• {P0732Condition 2}Transmission Gear=2nd Gear & Engine Torque=Less than -20 Nm (-15 lb ft) or Greater than 29 Nm (21 lb ft)
• {P0733Condition 1}Transmission Gear=3rd Gear
• {P0733Condition 2}Transmission Gear=3rd Gear & Engine Torque=Less than -20 Nm (-15 lb ft) or Greater than 29 Nm (21 lb ft)
• {P0734Condition 1}Transmission Gear=4th Gear
• {P0734Condition 2}Transmission Gear=4th Gear & Engine Torque=Less than -20 Nm (-15 lb ft) or Greater than 29 Nm (21 lb ft)
• {P0735Condition 1}Transmission Gear=5th Gear
• {P0735Condition 2}Transmission Gear=5th Gear & Engine Torque=Less than -20 Nm (-15 lb ft) or Greater than 29 Nm (21 lb ft)
• {P076FCondition 1}Transmission Gear=7th Gear {P076FCondition 2}Transmission Gear=7th Gear & Engine Torque=Less than -20 Nm (-15 lb ft) or Greater than 29 Nm (21 lb ft)
• {P07D9Condition 1}Transmission Gear=8th Gear
• {P07D9Condition 2}Transmission Gear=8th Gear & Engine Torque=Less than -20 Nm (-15 lb ft) or Greater than 29 Nm (21 lb ft)

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

Conditions for Setting the DTC

P0729, P0730, P0732, P0733, P0734, P0735, P076F, P07D9 - Condition 1

The following parameters are not within 20% of each other:Gear Ratio & Gear Command - For 1 s - Malfunction occurred 5 times.

P0729Condition 2

Gear Ratio=Incorrect gear ratio - Within 4% of gear 4, 5, 7, 8 ratio - For greater than 1 s - Malfunction occurred 5 times.

P0730Condition 2

Gear Ratio=Incorrect gear ratio - Within 4% of gear 3, 4 ratio - For greater than 1 s - Malfunction occurred 5 times.

P0730Condition 3

Gear Ratio=Incorrect gear ratio - Within 4% of gear 2, 5 ratio - For greater than 1 s - Malfunction occurred 5 times.

P0731

Gear Ratio=Incorrect gear ratio - Within 4% of gear 2, 4, 5 ratio - For greater than 1 s - Malfunction occurred 5 times.

P0732Condition 2

Gear Ratio=Incorrect gear ratio - Within 4% of gear 3, 4, 5, 8 ratio - For greater than 1 s - Malfunction occurred 5 times.

P0733Condition 2

Gear Ratio=Incorrect gear ratio - Within 4% of gear 2, 4, 5, 7 ratio - For greater than 1 s - Malfunction occurred 5 times.

P0734Condition 2

Gear Ratio=Incorrect gear ratio - Within 4% of gear 2, 3, 5, 6 ratio - For greater than 1 s - Malfunction occurred 5 times.

P0735Condition 2

Gear Ratio=Incorrect gear ratio - Within 4% of gear 2, 3, 4, 6, 7, 8 ratio - For greater than 1 s - Malfunction occurred 5 times.

P076FCondition 2

Gear Ratio=Incorrect gear ratio - Within 4% of gear 3, 5, 6, 8 ratio - For greater than 1 s - Malfunction occurred 5 times.

P07D9Condition 2

Gear Ratio=Incorrect gear ratio - Within 4% of gear 2, 5, 6, 7 ratio - For greater than 1 s - Malfunction occurred 5 times.

Actions Taken When the DTC Sets

DTCs listed in the DTC Descriptor Category=Type A DTC - Exceptions listed below - Additional actions taken:

DTC P0730=Type C DTC

• Autostart/Autostop=Disabled - If equipped
• Fail-Safe Mode=Enabled
• Learning=Disabled

Conditions for Clearing the DTC

DTCs listed in the DTC Descriptor Category=Type A DTC

DTC P0730=Type C 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. Ignition - On / Vehicle - In Service Mode

2. Verify there are no DTCs set related to the following system/component:

• Q27A Pressure Control Solenoid Valve 1
• Q27B Pressure Control Solenoid Valve 2
• Q27C Pressure Control Solenoid Valve 3
• Q27D Pressure Control Solenoid Valve 4
• Q27E Pressure Control Solenoid Valve 5
• Q27F Pressure Control Solenoid Valve 6
• Q32A Shift Solenoid Valve 1
• Q32B Shift Solenoid Valve 2
• If other DTCs are set

Refer to: Diagnostic Trouble Code (DTC) List - Vehicle

• Go to next step: If no other DTCs are set

3. Verify the condition does not exist:Incorrect fluid level or condition - Transmission - Refer to Transmission Fluid Level and Condition Check

• If a condition exists

Repair or replace as necessary.

• Go to next step: If no condition exists

4. Verify the condition does not exist:Incorrect pressure - Transmission - Refer to Line Pressure Check

• If a condition exists

Replace the component:T12 Automatic Transmission Assembly

• Go to next step: If no condition exists

5. Clear the DTCs.

6. Perform the configuration/reset function: Refer to Learned Values Reset

7. Road test the vehicle. - Refer to Road Test.

8. Verify DTC P0729, P0730, P0731, P0732, P0733, P0734, P0735, P076F, P07D9 is not set.

• {Test failed 1 time (s) }If any of the DTCs are set

1. Replace the component: K71 Transmission Control Module
2. Refer to:Step 5

• {Test failed 2 time (s) }If any of the DTCs are set

1. Replace the component: Control Valve Body
2. Refer to:Step 5

• {Test failed 3 time (s) }If any of the DTCs are set

1. Replace the component: T12 Automatic Transmission Assembly
2. Refer to:Step 5

• Go to next step: If none of the DTCs are set

9. 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:Step 1

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

10. 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 Transmission Replacement
• For control module replacement, programming, and setup: Refer to Control Module: References

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