P0741

DTC P0741 Torque Converter Clutch Solenoid Performance (Shift Solenoid Valve SL)

SYSTEM DESCRIPTION

DTC Detection Conditions:

The ECM uses the signals from the throttle position sensor, air-flow meter and crankshaft position sensor to monitor the engagement condition of the lock-up clutch. Then the ECM compares the engagement condition of the lock-up clutch with the lock-up schedule in the ECM memory to detect mechanical trouble of the shift solenoid valve SL, valve body and torque converter clutch or automatic transaxle (clutch, brake or gear etc.).

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

Torque converter lock-up is controlled by the ECM based on speed sensor (NT), speed sensor (NO), engine rpm, engine load, engine temperature, vehicle speed, transmission temperature, and gear selection. The ECM determines the lock-up status of the torque converter by comparing the engine rpm (NE) to the input turbine rpm (NT). The ECM calculates the actual transmission gear by comparing input turbine rpm (NT) to counter gear rpm (NO). When conditions are appropriate, the ECM requests "lock-up" by applying control voltage to shift solenoid SL. When the SL is turned on, solenoid SL applies pressure to the lock-up relay valve and locks the torque converter clutch.

If the ECM detects no lock-up after lock-up has been requested or if it detects lock-up when it is not requested, the ECM interprets this as a fault in the torque converter clutch performance. The ECM will turn on the MIL and store the DTC.

Example:
When any of the following is met, the system judges it as a malfunction.
a. There is a difference in rotation between before and after torque converters even when the ECM commands lock-up.
(Engine speed is at least 100 rpm greater than input speed.)
b. There is no difference in rotation between before and after torque converters even when the ECM commands lock-up off.
(The difference between engine speed and input speed is less than 35 rpm.)

Wiring Diagram:

INSPECTION PROCEDURE

Step 1 - 2:

Step 3 - 4:

HINT: Performing the ACTIVE TEST using the Hand-held tester allows the relay, VSV, actuator and so on to operate without parts removal. Performing the ACTIVE TEST as a first step of troubleshooting is one of the method to shorten the labor time.

It is possible to display the DATA LIST during the ACTIVE TEST.




a. Warm up the engine.
b. Turn the ignition switch off.
c. Connect the hand-held tester to the DLC3.
d. Turn the ignition switch to the ON position.
e. Push the "ON" button of the the hand-held tester.
f. Select the item "DIAGNOSIS/ENHANCED OBD 11/ACTIVE TEST".
g. According to the display on tester, perform the "ACTIVE TEST".

HINT:
- This test can be conducted when the vehicle speed is 58 km/h (36 mph) or more.
- This test can be conducted with the 0/D gear.




h. Lightly depress the accelerator pedal and check that the engine speed does not change abruptly.

HINT:
- When changing the accelerator pedal opening angle while driving, if the engine speed does not change, lock-up is on.
- Slowly release, but not fully the accelerator pedal in order to decelerate. (Fully releasing the pedal will close the throttle valve and lock-up may be turned off.)