6T30/6T40/6T45 - Automatic Transmission
DTC P0741 or P0742
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 Descriptors
DTC P0741
- Torque Converter Clutch (TCC) - Stuck Off
DTC P0742
- Torque Converter Clutch (TCC) - Stuck On
Circuit/System Description
The torque converter clutch (TCC) pressure control (PC) solenoid is part of the control solenoid valve assembly which has no serviceable components. The TCC PC solenoid is a normally low pressure control solenoid. The TCC PC solenoid regulates transmission fluid pressure to the TCC regulator valve in the lower valve body and the TCC control valve in the fluid pump assembly. When vehicle operating conditions are appropriate to apply the converter clutch, the transmission control module (TCM) will increase TCC PC current flow (duty cycle) thereby increasing pressure to move the TCC control valve into the apply position. When the TCC is fully applied, the engine is coupled directly to the transmission. TCC release is accomplished by the TCM decreasing current flow, dropping the apply pressure thereby allowing the TCC control valve to move to the release position. The TCM calculates torque converter slip speed based on the RPM signal from the input speed sensor (ISS) and engine RPM provided by the engine control module (ECM).
Conditions for Running the DTC
P0741
* No DTCs P0101, P0102, P0103, P0121, P0122, P0123, P0716, P0717, P0722, P0723, P0742, P2762, P2763, or P2764.
* Throttle position signal is valid.
* Engine torque signal is valid.
* First range is not commanded.
* The ignition voltage is between 9.0 volts and 18.0 volts.
* The transmission fluid temperature (TFT) is 20-130°C (68-266°F).
* The calc. throttle position is greater than 8 percent.
* The engine torque is greater than 50 Nm (36 lb ft).
* The 2nd gear ratio is between 2.75-3.17.
* The 3rd gear ratio is between 1.78-2.04.
* The 4th gear ratio is between 1.35-1.55.
* The 5th gear ratio is between 0.93-1.07.
* The 6th gear ratio is between 0.70-0.80.
* The TCC is commanded ON.
P0742
* No DTCs P0101, P0102, P0103, P0121, P0122, P0123, P0716, P0717, P0722, P0723, P0741, P0742, P1715, P2762, P2763, or P2764.
* TCC is commanded off.
* Throttle position signal is valid.
* Engine torque signal is valid.
* The engine speed is between 500 RPM and 6,500 RPM.
* The ignition voltage is between 9.0 volts and 18.0 volts.
* The transmission fluid temperature (TFT) is 20-130°C (68-266°F).
* The calc. throttle position was greater than 20 percent and had not dropped below 3 percent.
* The engine torque is greater than 80 Nm (59 lb ft).
* Vehicle speed greater than 16 km/h (10 mph).
* Commanded gear is 2nd or greater.
* The gear ratio is between 0.69-3.17.
Conditions for Setting the DTC
P0741
* The TCC commanded pressure is greater than 340 kPa (49 psi).
* The TCM detects TCC slip greater than 100-150 RPM, depending on temperature of the fluid, for 6 seconds when the TCC is commanded ON 5 times during the same ignition cycle.
P0742
The TCM detects the TCC slip between -20 and +30 RPM for 3 seconds or greater when the TCC is commanded OFF 7 times during the same ignition cycle.
Action Taken When the DTC Sets
P0741
* DTC P0741 is a type A DTC.
* The TCM inhibits TCC.
P0742
* DTC P0742 is a type A DTC.
* The TCM forces the TCC to be applied.
* The TCM freezes transmission adaptive functions.
Conditions for Clearing the DIC/DTC
DTCs P0741 and P0742 are Type A DTCs.
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 (6T30/6T40/6T45 - Automatic Transmission)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
* Transmission General Description (Transmission General Description)
* Transmission Component and System Description (Transmission Component and System Description)
* Electronic Component Description (Electronic Component 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 (Programming and Relearning) for scan tool information
Special Tools
* DT-48616 Control Solenoid Test Plate
* DT-48616-10 Adapter Harness
Circuit/System Verification
1. Perform the Transmission Fluid Level and Condition Check (Transmission Fluid Level and Condition Check) to verify correct fluid level and condition.
2. Perform the Control Solenoid Valve and Transmission Control Module Assembly Cleaning (Control Solenoid Valve and Transmission Control Module Assembly Cleaning) in order to dislodge debris and free up the valves.
3. Engine idling in Park, verify with a scan tool the transmission ISS/OSS Supply Voltage parameter displays OK.
4. Engine idling in Park, observe the Transmission ISS parameter on the scan tool, while varying the engine speed. The Transmission ISS parameter should vary with engine speed and not drop out.
Note: Perform a scan tool snapshot during the road test.
5. Perform the Road Test (6T30/6T40/6T45 - Automatic Transmission). Verify the transmission operation performs as indicated in the road test instructions.
6. Review the snapshot transmission data parameters. Verify the engine and transmission data parameters display the correct values in all forward gear ranges.
* Engine Speed
* Engine Coolant Temperature
* Transmission ISS
* Transmission OSS
* Trans. Fluid Temp.
* Brake Switch
* TCC PC Sol. Pressure Cmd.
* TCC Slip Speed
7. 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. Refer to Solenoid Valve Pressure (Solenoid Valve Pressure).
• 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).
• If the control solenoid valve assembly does not pass the test, replace the control solenoid valve assembly.
4. Listed in the table below are conditions for each component that could set a DTC P0741 or P0742. Carefully inspect each component for that condition. Repair or replace as necessary.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Important: Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and Transmission Control Module Assembly Inspection).
* Refer to Control Module References (Programming and Relearning) for control solenoid valve assembly replacement, setup, and programming.
* Perform the Service Fast Learn Adapts (6T30/6T40/6T45 - Automatic Transmission) following all transmission related repairs.
* Perform the Torque Converter Removal (2. Torque Converter Removal) and the Torque Converter Installation (51. Torque Converter Installation).