6T70/6T75 - Automatic Transmission
DTC P0751 or P0752
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0751
- Shift Solenoid (SS) 1 Valve Performance - Stuck Off
DTC P0752
- Shift Solenoid (SS) 1 Valve Performance - Stuck On
Circuit/System Description
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 in 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 commands second gear and if second gear ratio is attained, this would indicate a stuck OFF SS valve 1 and the DTC sets.
Conditions for Running the DTC
P0751
* The commanded gear slip or attained gear slip is at lease 100 RPM.
* Intrusive Neutral Test neutral time is at least 3 seconds.
* First gear locked is commanded.
* The closest gear ratio is 4th gear.
P0752
* Commanded gear has achieved 1st lock, 1st free-wheel, or 2nd gear.
* Commanded gear is 3rd.
Conditions for Setting the DTC
P0751
Commanded gear equals first lock and gear ratio equals fourth and gear box slip is less than 100 RPM for 2.25 seconds.
P0752
Gear box slip is greater than 100 RPM for 3 seconds.
Action Taken When the DTC Sets
* DTC P0751 is a Type C DTC.
* DTC P0752 is a Type A DTC.
Conditions for Clearing the DTC
* DTC P0751 is a Type C DTC.
* DTC P0752 is a Type A DTC.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Transmission General Description (Transmission General Description)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
* DT-47825 Control Solenoid Test Plate
* J 21867 Pressure Gage
Circuit/System Verification
1. Perform the Transmission Fluid Check (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 (Removal and 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 (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.
Circuit/System Testing
1. Ignition OFF, remove the line pressure test hole plug and install the J 21867 to the transmission.
2. Perform the Line Pressure Check (Line Pressure Check). Verify the transmission line pressure gage is within 35 kPa (5 psi) of that indicated on the scan tool.
• If not within the specified range, repair as necessary. Refer to Fluid Pressure High or Low (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-47825 to the control solenoid (w/body and TCM) valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test (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 (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.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Important:
* Perform the Service Fast Learn Adapts (Programming and Relearning) following all transmission related repairs.
* Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and Transmission Control Module Assembly Inspection).
Control Module References (Programming and Relearning) for control solenoid (w/body and TCM) valve assembly replacement, setup, or programming