DTC Advanced Diagnostics: P0741
DTC P0741:Torque Converter Clutch Circuit Performance or Stuck OFF

General Description

The power transfer capacity of the torque converter clutch is controlled by the balance of transmission fluid supply to and discharge from the torque converter. When hydraulic pressure is applied internally, the torque converter clutch turns ON, and when hydraulic pressure is applied from the back pressure side, the torque converter clutch turns OFF. As the hydraulic pressure from the internal pressure side increases, the power transfer capacity of the torque converter clutch increases. The direction of hydraulic pressure supply is switched by shift solenoid valve B and the LC shift valve. Transmission fluid is supplied from the internal pressure side to shift solenoid valve B when the signal from the transmission control module (TCM) is ON (12 V), and transmission fluid is supplied from the back pressure side when it is OFF (0 V). The balance of internal pressure and back pressure is controlled by the CVT lock-up clutch control solenoid valve and the LC control valve. The CVT lock-up clutch control solenoid valve maximizes the power transfer capacity of the torque converter clutch when the signal from the TCM is ON (1 A), and it minimizes the power transfer capacity of the torque converter clutch when the signal from the TCM is OFF (0 A). If the ratio of engine speed and input shaft speed is not about 1:1 while the TCM is issuing the command to turn shift solenoid valve B and the CVT lock-up clutch control solenoid valve ON, the TCM detects a faulty lock-up control system and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration
30 seconds or more
DTC Type
Two drive cycles, MIL on, Shift position indicator blinks

Enable Conditions
Condition
Minimum
Maximum
Engine speed [Engine Speed]
1,000 rpm
–
Vehicle speed [Vehicle Speed]
28 mph (45 km/h)
–
Accelerator pedal position variation
–
13 °/1 second
Shift position/mode
Without paddle shifter
D, S, L
With paddle shifter
D, S
[ ]: HDS Parameter

Malfunction Threshold
Difference between target torque converter slip rate and actual torque converter slip rate is more than 15 % for at least 30 seconds or more.

Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
Torque converter clutch failure
CVT lock-up clutch control solenoid valve stuck off
Shift solenoid valve B stuck off
LC shift valve stuck
LC control valve stuck

Confirmation Procedure
Operating Condition

1.
Start the engine.
2.
With the brake pedal pressed, place the shift lever from N position/mode to D position/mode.
3.
Drive the vehicle at a steady speed of 37 mph (60 km/h), for at least 1 minute.
4.
Slow down and stop the vehicle.
5.
Turn the vehicle to the OFF (LOCK) mode.
6.
Repeat Driving Pattern steps 1 through 4.
Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
With the HDS
None.

Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the TCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on, the shift position indicator blinks, and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC
The shift position indicator comes off by turning the vehicle to the OFF (LOCK) mode. The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command.