P0741

DTC P0741: Abnormality in Lock-up Function

DIAGNOSTIC FUNCTION
Abnormality is detected by the TCM when the torque converter slip speed is high during lockup control.

DESCRIPTIONS OF MONITOR METHODS
^ The status with the high torque converter slip speed continues for 30 seconds during lockup control [Primary pulley speed and engine speed are normal, and lockup differential pressure is 0.2 MPa (29 psi) or more].

MONITOR EXECUTION
^ Continuous

MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
^ P0746: Abnormality in hydraulic control system function
^ P0841: Abnormality in line pressure sensor function
^ P0868: Secondary pressure drop

Sensor (The sensor below is determined to be normal)
^ Not applicable

LOGIC FLOW CHARTS (Monitor Sequence)

Logic Flow Charts (Monitor Sequence):

DTC SET CONDITIONS

Check Conditions
^ Transmission range switch position: D.
^ Vehicle speed: 10 km/h (6.2 mph) or more.
^ Throttle position: 1/8 or more.
^ Engine speed: 450 r/min or more.
^ Transmission fluid temperature: 20°C (68°F) or more.
^ Transmission fluid temperature: 99°C (210°F) or less.
^ Voltage of battery: 9 volts or more.
^ Voltage of battery: 16 volts or less.
^ Transmission range switch: normal.
^ Secondary pulley speed sensor: normal.
^ Line pressure solenoid valve performance: normal.
^ Lock-up solenoid valve performance: normal.
^ Primary pulley speed sensor: normal.
^ Stepper motor: normal.
^ Lock-up solenoid valve: normal.
^ Line pressure solenoid valve: normal.
^ Throttle position sensor: normal.
^ Engine revolution: normal.
^ Secondary pressure solenoid valve: normal.
^ Secondary pressure solenoid valve performance: normal.
^ Lock-up selection solenoid valve performance: normal.
^ Primary pressure sensor: normal.
^ Secondary pressure sensor: normal.
^ Primary or secondary pressure sensor performance: normal.

Judgement Criteria
^ Torque converter slip revolution [primary pulley speed sensor: normal, Engine revolution: normal, lock-up pressure: 0.2 MPa (29 psi) or more]: 40+(vehicle speed/2) or more. (30 seconds)

OBD-II DRIVE CYCLE PATTERN
All the conditions below continue for 3 seconds.
^ In lock-up range
^ Lock-up pressure is 0.54 MPa or more.

PROBABLE CAUSES
^ Abnormal line pressure
^ Malfunction of TCM

DIAGNOSTIC PROCEDURE

STEP 1. Check other diagnosis codes.

Q: Are other diagnosis codes set?
YES: Carry out the appropriate troubleshooting.
NO: Go to Step 2.

STEP 2. M.U.T.-III data list
^ Item 7: Primary speed
^ Item 9: Engine revolution

OK: No considerable difference is observed between the primary pulley speed and the engine speed.

Q: Is the check result normal?
YES: Intermittent malfunction
NO: Go to Step 3.

STEP 3. Line Pressure Check
Carry out "hydraulic test". Component Tests and General Diagnostics

Q: Is the check result normal?
YES: Go to Step 4.
NO: Repair according to the hydraulic pressure test diagnosis table.

STEP 4. Symptom recheck after erasing diagnosis code

Q: Is the check result normal?
YES: Intermittent malfunction
NO: Replace TCM.