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Home >> Buick >> 2010 >> Allure AWD (CANADA) V6-3.0L >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P1751 >> 6T30/6T40/6T45 - Automatic Transmission

6T30/6T40/6T45 - Automatic Transmission




DTC P1751

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC P1751
- Shift Valve 1 Performance

Circuit/System Description

The shift solenoid (SS) 1 is part of the control solenoid valve assembly, which has no serviceable components. SS 1 provides fluid pressure to control the operation of the clutch select valve 2, which is located in the control valve body assembly. SS 1, in conjunction with clutch select valve 2, controls fluid to the R1 and 4-5-6 clutches. A diagnostic test is performed by the transmission control module (TCM) to determine the state of the clutch select valve 2. During this diagnostic test, the TCM commands the SS 1 ON, supplying pressure to move the clutch select valve 2 toward its spring. At the same time, line pressure is elevated slightly to assist the spring side pressure. If the spring is broken, or the clutch select valve 2 cannot move due to another mechanical condition, the DTC will set.

Conditions for Running the DTC

* No ISS DTCs P0716 or P0717.
* No OSS DTCs P0722 or P0723.
* No TCC Performance DTCs P0741 or P0742.
* No TCC Electrical DTCs P2763, P2763, or P2764.
* DTC 1751 has not failed this ignition cycle.
* The engine run time is greater than 5 seconds.
* The ignition voltage is between 8.6 volts and 19.0 volts.
* The transmission fluid temperature (TFT) is 20-130°C (68-266°F).
* The calc. throttle position is 8 percent or greater.
* The engine torque is greater than 80 Nm (59 lb ft).
* No upshift or downshift in process.
* The attained gear slip is equal to or greater than 100 RPM.
* The TCC is commanded OFF.
* Vehicle speed is greater than 16 km/h (20 mph).
* The TISS is equal to or greater than 1,100 RPM.
* Commanded gear is 2nd or greater.
* The gear ratio is between 0.69-1.97.
* Solenoid A is enabled.

Conditions for Setting the DTC

The TCM detects attained gear slip is 150 RPM or greater for 0.5 second 5 times during the same ignition cycle.

Action Taken When the DTC Sets

DTC P1751 is a Type B DTC.

Conditions for Clearing the DTC

DTC P1751 is a Type B DTC.

Diagnostic Aids

DTC P1751 detects gear box slip when the mode 2 valve solenoid is commanded on as part of the P0742 TCC stuck OFF test.

Reference Information
Description and Operation

* Transmission General Description (Transmission General Description)
* Transmission Component and System Description (Transmission Component and System Description)
* Electronic Component Description (Electronic Component Description)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Perform the Transmission Fluid Level and Condition Check (Transmission Fluid Level and Condition Check) to verify correct fluid level and condition.

Note: Perform a scan tool snapshot during the road test.

2. Perform the Road Test (6T30/6T40/6T45 - Automatic Transmission). Verify the transmission operation performs as indicated in the road test instructions.
3. Review the scan tool snapshot transmission data parameters. Verify the following engine and transmission data parameters display the correct values in all forward gear ranges.

* Engine Speed
* Vehicle Speed
* Transmission ISS
* Transmission OSS
* Shift Solenoid Valve 1
* Gear Command

4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Note: You must perform the Circuit/System Verification first.

1. Perform the Line Pressure Check (Line Pressure Check). Verify the transmission line pressure gauge is within the range specified in the Line PC Solenoid Valve Pressure table. Refer to Solenoid Valve Pressure (Solenoid Valve Pressure).

• If not within the specified ranges, refer to Fluid Pressure High or Low (Fluid Pressure High or Low) for further diagnosis.

2. Ignition OFF, remove the control solenoid valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Replacement (6T30/6T40/6T45 - Automatic Transmission).
3. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test (Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test).

• If the control solenoid valve assembly does not pass the performance test, replace the control solenoid valve assembly.

4. Listed in the table below are conditions for each component that could set DTC P1751. Carefully inspect each component for that condition. Repair or replace as necessary.





Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Important: Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and Transmission Control Module Assembly Inspection).


* Refer to Control Module References (Programming and Relearning) for control solenoid valve assembly replacement, setup, and programming.
* Perform the Transmission Adaptive Values Learn (6T30/6T40/6T45 - Automatic Transmission) following all transmission related repairs.

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