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

The transmission input shaft speed is 1,200 RPM or greater, then maintain above 900 RPM.

### Conditions for Setting the DTC

• | The transmission case slip speed is 100 RPM or greater.

• | The above conditions occur 8 times consecutively.

### 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

When attempting to set transmission performance DTCs, observe the Freeze Frame and Failure Records to assist in duplicating the failure conditions. Ensure the transmission fluid level is correct and there are no leaks.

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### DTC Type Reference

• | Diagnostic Trouble Code (DTC) Type Definitions

• | Diagnostic Trouble Code (DTC) List/Type

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Verification

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.

⇒ | If the DTC resets, go to Component Testing.

### Component Testing

Inspect the lower control valve body for a stuck clutch select valve 2, a broken clutch select valve 2 spring, debris or damage.

⇒ | If you found a valve body concern, repair or replace the lower control valve body as necessary.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Control Valve Lower Body and Upper Body Replacement

• | Service Fast Learn Adapts