For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### 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

• | gasket leaking

P0741, P0742

Torque Converter |

• | incorrect transmission fluid level

• | clogged hydraulic system

• | mechanically stuck in the applied position

• | gasket leaking

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.

• | 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 between 10.2 V and 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

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

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### 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

1. Perform the line pressure check Line Pressure Check.
2. Perform the transmission fluid check Transmission Fluid Check.
3. 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

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 after completing the diagnostic procedure.

• | Perform the torque converter diagnosis Torque Converter Diagnosis.

• | Control valve body replacement. Refer to Control Valve Body Replacement for replacement, setup and programming.

• | TCM, refer to Control Module References for replacement, setup and programming.

⇒ | Perform the Transmission Adaptive Functions.