Diagnostic Instructions
DTC Descriptor
DTC P0741: Torque Converter Clutch (TCC) System Stuck Off
DTC P0742: Torque Converter Clutch (TCC) System Stuck On
Diagnostic Fault Information
Component
| Condition
| DTCs
|
Valve Body Assembly
|
• | incorrect transmission fluid level |
• | clogged hydraulic system |
• | plugged or restricted passages |
| P0741, P0742
|
Torque Converter
|
• | incorrect transmission fluid level |
• | clogged hydraulic system |
• | mechanically stuck in the applied position |
| P0741, P0742
|
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 between 10.2 V and 15.5 V. |
• | The engine speed is greater less 4 000 RPM. |
• | Engine torque is more than 0 N·m (0 ft-lb). |
• | The transmission is not in emergency mode. |
• | TCM communication is normal. |
• | DTCs P0716, P0717, P0721, P0722, P2759, P2762, P2763, P2764 are not set |
P0742
• | The ignition voltage is between 10.2 V and 15.5 V. |
• | The engine speed is greater than 400 RPM. |
• | The transmission is not in emergency mode. |
• | TCM communication is normal. |
• | DTCs P0716, P0717, P0721, P0722, P2759, P2762, P2763, P2764 are 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 100 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
• | DTC P0741 is a Type B DTC. |
• | DTC P0742 is a Type B DTC. |
• | The TCM freezes transmission adaptive functions. |
Conditions for Clearing the DTC
P0741
• | DTC P0741 is a Type B DTC. |
• | Deviation between Engine speed and output speed is less than 30 RPM during lockup control is turned on. |
• | DTC P0742 is a Type B DTC. |
• | Deviation between Engine speed and output speed is more than 100 RPM during lockup control is turned off. |
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, colour 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
Connector End View Reference
Component Connector End Views
Electrical Information Reference
Description and Operation
Transmission Component and System Description
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
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.
⇒ | Verify the DTC does not reset. If the DTC resets and no other DTC is set, go to Circuit/System Testing. |
⇒ | If any other DTC is set, diagnose that DTC first. |
Circuit/System Testing
Dynamic Test
- Perform the line pressure check
Line Pressure Check.
- Perform the transmission fluid check
Transmission Fluid Check.
- If all circuits test normal, replace the K71 Transmission Control Module (TCM). Verify the DTC does not reset.
⇒ | If the DTC resets, go to Component Testing. |
Component Testing
- Inspect the valve body assembly for a stuck valve, debris or damage.
⇒ | If a stuck open or closed valve is found, replace the valve body assembly. |
- Inspect the torque converter assembly for damage or discoloration.
⇒ | If you find a torque converter assembly concern, replace the torque converter assembly as necessary. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.