P0741

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

SYSTEM DESCRIPTION
The TCM uses signals from the throttle position sensor, air-flow meter, turbine (input) speed sensor, intermediate (counter) speed sensor and crankshaft position sensor to help determine the engagement timing of the lock-up clutch. The TCM monitors the engagement of the clutch using the turbine (input) speed sensor, intermediate (counter) speed sensor and crankshaft position sensor.
Then the TCM compares the engagement condition of the lock-up clutch with the lock-up schedule in the TCM memory to detect shift solenoid valve SL, valve body and torque converter clutch mechanical problems.





MONITOR DESCRIPTION
Torque converter lock-up is controlled by the TCM based on the speed sensor (NT), speed sensor (NC), engine rpm, engine load, engine temperature, vehicle speed, transmission fluid temperature, and gear selection. The TCM determines the lock-up status of the torque converter by comparing the engine rpm (NE) to the input turbine rpm (NT). The TCM calculates the actual transmission gear by comparing the input turbine rpm (NT) to the counter gear rpm (NC). When conditions are appropriate, the TCM requests "lock-up" by applying control voltage to the shift solenoid SL. When the SL is turned on, it applies pressure to the lock-up relay valve and locks the torque converter clutch.
If the TCM detects no lock-up after lock-up has been requested or if it detects lock-up when it is not requested, the TCM interprets this as a fault in the shift solenoid valve SL or lock-up system performance. The TCM will turn on the MIL and store the DTC.

HINT:
Example:
When any of the following is met, the system judges it as a malfunction.
^ There is a difference in rotation between the input side (engine speed) and output side (input turbine speed) of the torque converter when the TCM commands lock-up.
(Engine speed is at least 70 rpm greater than the input turbine speed.)
^ There is no difference in rotation between the input side (engine speed) and output side (input turbine speed) of the torque converter when the TCM commands lock-up off.
(The difference between the engine speed and input turbine speed is less than 20 rpm.)

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





INSPECTION PROCEDURE

HINT: Performing the ACTIVE TEST using the intelligent tester allows relays, VSVs, actuators and so on to operate without removing any parts. Performing the ACTIVE TEST as the first step in troubleshooting is one method to save labor time.

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

1. PERFORM ACTIVE TEST
(a) Warm up the engine.
(b) Turn the engine switch off.
(c) Connect the intelligent tester to the DLC3.
(d) Turn the engine switch on (IG).
(e) Turn the intelligent tester on.
(f) When using the intelligent tester:
Enter the following items: "DIAGNOSIS / OBD/MOBD / ECT / ACTIVE TEST".
(g) According to the display on the tester, perform "ACTIVE TEST".





HINT:
^ This test can be conducted when the vehicle speed is 37 mph (60 km/h) or more.
^ This test can be conducted in the 6th 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.)

Step 1 (Part 1):

Step 1 (Part 2), Step 2-3:

Step 4-6: