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

### Diagnostic Fault Information

The following fault table gives examples of how hydraulic circuit problems and malfunctioning hard parts affect the transmission operation.

Component | Cause | DTCs
--- | --- | ---
Automatic Transmission Fluid Pump Cover Assembly | TCC control valve stuck in fluid pump cover assembly | P1751
Control Solenoid (w/body and TCM) Valve Assembly | Shift Solenoid 1:

• | Always exhausting - Stuck On

• | Not exhausting - Stuck Off

• | Needle piston or armature pin binding

• | Control signal fluid supply leak - valve body filter plate assembly cracked or damaged gasket seal

• | Control valve body spacer plate assembly number 4 ball check valve orifice damaged or burred

P1751

### 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.

• | 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

#### Description and Operation

• | Transmission General Description

• | Transmission Component and System Description

• | Electronic Component Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### 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 .
2. While operating the vehicle in drive with the calculated throttle position greater than 8 percent and the attained gear slip less than 1,100 RPM, command the TCC is commanded ON and OFF a minimum of 5 times.

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

3. 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

Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Perform the Line Pressure Check .

⇒ | If the pressure is out of specification, correct this concern first.

2. Perform the Control Solenoid Valve and Transmission Control Module Assembly Cleaning procedure in an attempt to clean or free up a potential sticking valve of dirt or debris. Retest the DTC as outlined in the Circuit/System Verification steps.

⇒ | If the DTC resets after the cleaning procedure perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection .

3. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test .

⇒ | If the SS 1 is found to be leaking or stuck, replace the control solenoid (w/body and TCM) valve assembly.

⇒ | If the control solenoid (w/body and TCM) valve assembly shift solenoid functions correctly, inspect the lower control valve body assembly for the following:

• | Clutch select valve 2 (CSV2) and valve body bore for scratches, gouges, scuffing, scoring, debris, or damage. The valve should move freely in the bore without stopping or binding.

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

• | Inspect the CSV2 fluid circuits for blockage.

• | Inspect the CSV2 valve spring for damage, distortions, or broken coils.

4. Inspect the TCC control valve in the pump cover assembly.

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

5. Inspect the torque converter assembly for damage or discoloration.

⇒ | If you found a torque converter assembly concern, replace the torque converter assembly as necessary.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

| Important: 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.

• | Perform the:

- | Control Valve Body Assembly Removal

- | Control Valve Body Assembly Disassemble

- | Control Valve Body Cleaning and Inspection

- | Control Valve Channel Plate Cleaning and Inspection

- | Control Valve Body Assembly Assemble

- | Control Valve Body Assembly Installation

• | Perform the:

- | Torque Converter Removal and the Torque Converter Installation .

- | Torque Converter Housing with Fluid Pump Assembly Removal

- | Transmission Fluid Pump Disassemble

- | Transmission Fluid Pump Assemble

- | Torque Converter Housing with Fluid Pump Assembly Installation