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DTC P0741: Abnormality in Lock-up Function
 
 
 
 
DIAGNOSTIC FUNCTION
Abnormality is detected by the TCM when the torque converter slip speed is high during lock-up control.
 
 
DESCRIPTIONS OF MONITOR METHODS
While the lock-up control, all the conditions listed below remain for 30 seconds.
  • Slip speed is higher than the judgment value.
  • The lock-up differential pressure is more than 0.2 MPa (29 psi).
 
 
MONITOR EXECUTION
  • Voltage of battery: 10 volts or more.
 
 
MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Not applicable
 
 
LOGIC FLOW CHARTS (Monitor Sequence)
 
 
DTC SET CONDITIONS
Check Conditions
  • Voltage of battery: 10 volts or more.
  • Lock-up pressure: More than 0.2 MPa (29 psi).
Judgment Criteria
  • Engine speed - Turbine speed: 40 + (vehicle speed / 2) r/min or more (30 seconds).
 
 
OBD-II DRIVE CYCLE PATTERN
Transmission range: D (Drive the vehicle for 30 seconds or more while the accelerator opening angle is 20% or more).
 
 
PROBABLE CAUSES
  • Malfunction of valve body assembly (Faulty lock-up solenoid valve)
  • Malfunction of the CVT assembly
 
 
DIAGNOSIS
Required Special Tools
  • MB992006: Extra fine probe
STEP 1. Scan tool (M.U.T.-IIISE) diagnostic trouble code.
Is diagnostic trouble code No. P2763 or P2764 set?
Carry out the appropriate troubleshooting.
Go to Step 2.
 
STEP 2. Measure the output wave pattern of the lock-up solenoid valve at TCM connector (LULS terminal).
(1) Connect the CVT assembly connector.
(2) Selector lever position: D.
(3) Accelerator pedal opening angle: 12.5% or less.
(4) Drive at a constant speed of approx. 20 km/h (13 mph).
(5) Connect an oscilloscope, and measure the voltage between TCM connector LULS terminal and body ground.
OK: A wave pattern such as the one shown on (Check Procedure Using an Oscilloscope) should be output. There should be no noise in the output wave pattern.
Is the check result normal?
Go to Step 3.
Refer to diagnostic trouble code No.P2763: Malfunction of Lock-up Solenoid Valve (high input) , or diagnostic trouble code No.P2764: Malfunction of Lock-up Solenoid Valve (low input) .
 
STEP 3. Symptom recheck after erasing diagnostic trouble code.
Turn the ignition switch to the "LOCK" (OFF) position, and wait for one minute. Then, drive the vehicle for a while and check again.
Is the diagnostic trouble code set?
Replace the CVT assembly.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunctions ).