AF40-6 (MDK) - 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) System Stuck Off
DTC P0742
- Torque Converter Clutch (TCC) System Stuck On
Diagnostic Fault Information
Circuit/System Description
Based on input speed and output speed signals, signals from the engine control module (engine speed and throttle opening) and vehicle speed, smooth lock-up control and slip is performed through the lock-up control solenoid (SLU). The SLU is linearly turned ON and OFF. The lock-up clutch inside the torque converter is operated, and the pump impeller and turbine runner are connected. Through this, the engine and the automatic transmission are coupled and engine output is connected directly to the automatic transmission, eliminating transmission loss. Sliding the lock-up clutch when lock-up is in the OFF range, extends the lock-up range to low vehicle speeds. It also suppresses a rise in engine speed and increases transmission efficiency, improving fuel economy and at the same time, through the sliding of the lockup clutch, engine vibration can be absorbed by the torque converter.
Conditions for Running the DTC
P0741
* The ignition voltage is 10.2-15.5 V.
* The engine speed is greater less 4 000 RPM.
* Engine torque is more than 0 Nm (0 lb ft).
* The transmission is not in emergency mode.
* Driving in D range.
* Transmission control module (TCM) communication is normal.
* DTCs P0716, P0717, P0721, P0722, P2759, P2762, P2763 and P2764 not set.
P0742
* The ignition voltage is 10.2-15.5 V.
* The engine speed is greater than 400 RPM.
* Output speed is 0 RPM.
* The transmission is not in emergency mode.
* Driving in D range.
* Transmission control module (TCM) communication is normal.
* DTCs P0716, P0717, P0721, P0722, P2759, P2762, P2763 and P2764 not set.
Conditions for Setting the DTC
P0741
Detected slip speed is more than 100 RPM 2 s after lockup control is turned on.
P0742
* Detected slip speed is less than 30 RPM 2 s after lockup control is turned off.
* Detects no slip speed in engine stall avoidance control after engine stall detected or no slip speed detected during no lockup control.
Action Taken When the DTC Sets
* DTCs P0741 and P0742 are Type B DTCs.
* The TCM inhibits TCC.
* The TCM freezes transmission adaptive functions.
Conditions for Clearing the DTC
* DTCs P0741 and P0742 are Type B DTCs.
* Deviation between Engine speed and output speed is less than 30 RPM during lockup control is turned on.
* Deviation between Engine speed and output speed is more than 100 RPM during lockup control is turned off.
Diagnostic Aids
Ensure the transmission fluid level, color and odor is correct and there are no leaks. If there are any other transmission DTCs set, diagnose those first.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics AF40-6 (MDK) - Automatic Transmission
Connector End View Reference
Component Connector End Views Sunshade - Left
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
Description and Operation
Transmission Component and System Description Transmission Component and System Description
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
1. Ignition ON.
2. Verify there are no other DTCs set.
• If any other DTC are set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
• If none DTC are set
3. Operate the vehicle in drive with the calculated throttle position greater than 8% and ensure TCC is commanded ON and OFF a minimum of 5 times.
4. Verify the DTC P0741 or P0742 is not set.
• If the DTC is set
Refer to Circuit/System Testing.
• If the DTC is not set
5. Operate the vehicle within the Conditions for Running the DTC. It may be helpful to operate the vehicle within the conditions identified from the Freeze Frame/Failure Records data.
6. Verify the DTC do not set.
• If the DTC is set
Refer to Circuit/System Testing.
• If the DTC is not set
7. All OK.
Circuit/System Testing
Dynamic Test
1. Perform the line pressure check. Refer to Line Pressure Check Line Pressure Check.
• If the line pressure check not OK
Repair or replace the damaged component as necessary.
• If the line pressure check OK
2. Perform the Torque Converter Diagnosis Torque Converter Diagnosis
• If the Torque Converter Diagnosis not OK
Repair or replace the damaged component as necessary.
• If the Torque Converter Diagnosis OK
3. Perform the Road Test Road Test to verify that not DTCs set.
• If DTC P0741 or P0742 is set
Refer to Component Testing
• If the DTC is not set
4. All OK.
Component Testing
Static Test
1. Inspect the valve body assembly for a stuck valve, debris, or damage. Refer to Control Solenoid Valve Inspection AF40-6 (MDK) - Automatic Transmission.
• If a stuck open or closed valve is found
Replace the valve body assembly.
• If no stuck open or closed valve is found
2. Inspect the torque converter assembly for damage or discoloration.
• If a torque converter assembly defect is found
Replace the torque converter assembly as necessary.
• If the torque converter assembly OK
Replace the K71 Transmission Control Module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Control valve body replacement, refer to Control Valve Body Replacement Control Valve Body Replacement
* Torque converter replacement, refer to Torque Converter Replacement Service and Repair
* Refer to Control Module References Control Module References for TCM replacement, programming and setup.
* Perform the Transmission Adaptive Functions Transmission Adaptive Functions.