P0756
DTC P0756
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P0756
- Shift Solenoid (SS) 2 Valve Performance - Stuck Off
Circuit/System Description
The shift solenoid (SS) valve 2 is part of the control solenoid valve assembly, which has no serviceable components. The SS valve 2 is a normally closed (NC) solenoid valve and controls fluid to the clutch select valve 3. The solenoid operates by the transmission control module (TCM) opening or closing the ground circuit. With the solenoid circuit grounded, solenoid on, the internal plunger moves and allows the metering ball to move away from the feed seat and against the exhaust seat, creating signal fluid pressure. The signal fluid acts against the clutch select valve 3 to overcome the valve spring force, moving it to the apply position.
Conditions for Running the DTC
* No DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0171, P0172, P0174, P0175, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0401, P042E, P0716, P0717, P0722, P0723, or P182E.
* The engine speed is 400 RPM or greater for 5.0 seconds.
* The high side driver is enabled.
* The ignition voltage is 8.6 volts or greater.
* Throttle position signal is valid.
* Transmission fluid temperature (TFT) is 0°C (32°F) or greater.
Conditions for Setting the DTC
* Commanded Gear is 1st locked.
* Gearbox Slip is 200 RPM up or greater for 3 seconds.
* If above conditions exist, the TCM will command second range. If the gear ratio is between 2.7 and 3.0 for 1 second, the counter will increment, and the DTC will set after 5 occurrences.
Action Taken When the DTC Sets
* DTC P0756 is a Type A DTC.
* The TCM inhibits Tap Up/Down function.
* The TCM inhibits manual shifting of forward gears.
* The TCM commands maximum line pressure.
* The TCM freezes transmission adaptive functions.
* The TCM limits the transmission to reverse, first, and third range operation.
Conditions for Clearing the DTC
DTC P0756 is a Type A DTC.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics Electrical Diagrams
Connector End View Reference
* Component Connector End Views Connector End Views By Name
* Inline Harness Connector End Views Connector Views
Description and Operation
Transmission General Description Transmission General Description
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
Note: If other DTCs are set, diagnose those DTCs first.
1. Perform the Transmission Fluid Level and Condition Check Transmission Fluid Level and Condition Check to verify correct fluid level and condition.
Note: Perform a scan tool snapshot, during the road test.
2. Perform the Road Test 6T70/6T75 - Automatic Transmission. Verify the transmission operation performs as indicated, in the road test instructions.
3. Review the scan tool snapshot transmission data parameters. Verify the engine and transmission data parameters display the correct values in all forward gear ranges:
* Engine Speed
* Transmission ISS
* Transmission OSS
* Vehicle Speed
* Shift Solenoid 2
* TFP Switch 1
* TFP Switch 3
* TFP Switch 4
* TFP Switch 5
4. Record the Freeze Frame/Failure Records data. Clear the DTCs.
5. Engine running, brakes applied, transmission gear shift selector in reverse. Shift to drive and accelerate to 56 km/h (35 mph) with calculated throttle position greater than 15 percent. Perform this test 5 consecutive times. The DTC should not set.
6. 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. Perform the Line Pressure Check Line Pressure Check. Verify the transmission line pressures are within the range specified in the Line PC Solenoid Valve Pressure table.
• If not within the specified ranges, refer to Fluid Pressure High or Low Fluid Pressure High or Low.
2. Ignition OFF, remove the control solenoid valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Replacement Service and Repair.
3. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test. Test all solenoids on the control solenoid valve assembly. A pressure change should occur for each solenoid valve.
• If the control solenoid valve assembly does not pass the performance test, replace the control solenoid valve assembly.
4. Listed in the table below are conditions for each component that could set DTC P0756. Carefully inspect each component for that condition. Repair or replace as necessary.
Repair Instructions
Note:
* Perform the Reset Transmission Adapts Programming and Relearning following all transmission related repairs.
* Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection Component Tests and General Diagnostics.
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Control Valve Upper Body Assembly Cleaning and Inspection 50. Control Valve Upper Body Assembly Cleaning and Inspection
* Control Module References Control Module References
for control solenoid valve assembly replacement, setup, or programming