For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

DTC P1751: Shift Valve 1 Performance

### Circuit/System Description

The shift valve 1 (clutch select valve 2) is part of the lower control valve body. The shift valve 1 (clutch select valve 2) controls fluid to the R1 and 4-5-6 clutches. During this diagnostic test, intrusive actions are taken by the transmission control module (TCM) to test the clutch select valve 2 to see if the valve is stuck. The TCM commands the shift solenoid (SS) 1 ON to put pressure on the valve towards the spring and at the same time, elevates line pressure slightly to assist the spring side pressure. If the spring is broken, the valve will slip back towards the spring indicating a mechanical failure and 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 N·m (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 Component and System Description

• | Electronic Component Description

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Perform the Transmission Fluid Check to verify correct fluid level and condition. The transmission fluid level should be within the crosshatch band and the transmission fluid should be red or dark brown.

⇒ | If the transmission fluid is low or discolored, refer to Transmission Fluid Replacement.

2. Perform the Control Solenoid Valve and Transmission Control Module Assembly Cleaning to dislodge debris and free up the valves.
3. Operate the vehicle in drive with the calculated throttle position greater than 8 percent and ensure the TCC is commanded ON and OFF a minimum of 5 times. The DTCs should not set.

⇒ | If a DTC sets, inspect the lower control valve body for a stuck clutch select valve 2, a broken clutch select valve 2 spring, debris or damage and repair or replace as necessary.

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.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

| Note: Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection.

• | Refer to Control Module References for control solenoid (w/body and TCM) valve assembly replacement, setup, and programming.

• | Perform the Service Fast Learn Adapts following all transmission related repairs.