AF40-6 - 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.
* TCM communication is normal.
* DTCs P0716, P0717, P0721, P0722, P2759, P2762, P2763, P2764 are 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.
* 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 inhibits TCC.
* 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

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 - Automatic Transmission)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
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 (Programming and Relearning) 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
1. Perform the line pressure check. Refer to Line Pressure Check (Line Pressure Check).
2. Perform the transmission fluid check. Refer to Transmission Fluid Level and Condition Check (Transmission Fluid Level and Condition Check).
3. If all circuits test normal, replace the K71 Transmission Control Module. Verify the DTC does not reset.

• If the DTC resets, go to Component Testing.

Component Testing

Static Test
1. 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.

2. 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 (Verification Tests) after completing the diagnostic procedure.

* Perform the torque converter diagnosis. Refer to Torque Converter Diagnosis (Torque Converter Diagnosis).
* Control valve body replacement-Refer to Control Valve Body Replacement (Control Valve Body Replacement) for replacement, setup, and programming.
* TCM-Refer to Control Module References (Programming and Relearning) for replacement, setup, and programming.
* Perform the Transmission Adaptive Functions (Transmission Adaptive Functions).