The shift solenoid (SS) valve 1 is part of the lower control valve body. The SS valve 1 is a normally closed (NC) solenoid valve and controls fluid to the clutch select valve 3- and related clutches. During this diagnostic test, intrusive actions are taken by the transmission control module (TCM) to test the SS valve 1 to determine if the valve is stuck OFF. When attempting first gear engine braking, if first gear ratio is not achieved in a predetermined period of time and the closest gear ratio detected is fourth, the TCM will command second gear. If second gear ratio is attained this indicates a stuck OFF SS valve 1 and the DTC will set.

Commanded gear equals first lock and gear ratio equals fourth and gear box slip is less than 100 RPM for 0.125 seconds.

DTC P0751 is a Type B DTC.

Schematic Reference

Drive Range, First Gear Engine Braking

Connector End View Reference

Component Connector End Views

Description and Operation

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

For equivalent regional tools, refer to Special Tools.

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. Engine idling at operating temperature. Attempt to clean or free up a potential sticking valve with the scan tool Service Cleaning Procedure. Refer to Control Solenoid Valve and Transmission Control Module Assembly Cleaning for further instructions.
3. From a stop, accelerate to 56 km/h (35 mph) with the calculated throttle position greater than 15 percent. Perform this test 2 times. The DTCs should not set.
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.

1. Ignition OFF, remove the line pressure test hole plug and install the EN-21867 gage to the transmission.
2. Perform the Line Pressure Check. Verify the transmission line pressure gage is within the range specified in the Line PC Solenoid Valve Pressure table. Refer to Solenoid Valve Pressure.

⇒	If not within the specified range, repair as necessary. Refer to Fluid Pressure High or Low for further diagnosis.

3. Ignition OFF, remove the control solenoid (w/body and TCM) valve assembly.
4. Install the DT-48616 test plate to the control solenoid (w/body and TCM) valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test for detailed instructions.
5. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test. A pressure change should occur.

⇒	If a pressure change does not occur, replace the control solenoid (w/body and TCM) valve assembly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.