Monitor Description

Torque converter lock-up is controlled by the ECM based on the transmission revolution sensor (NT), transmission revolution sensor (NC), engine speed, engine load, engine temperature, vehicle speed, automatic transaxle fluid temperature, and gear selection. The ECM determines the lock-up status of the torque converter by comparing the engine speed (NE) to the input turbine speed (NT). The ECM calculates the actual transmission gear by comparing the input turbine speed (NT) to the output shaft speed (NC). When certain conditions are met, the ECM requests "lock-up" by cutting control voltage to the solenoid (SL) valve. When the solenoid (SL) valve is turned off, pressure is applied to the lock-up relay valve and the torque converter is locked.

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 solenoid (SL) valve or lock-up system performance. The ECM will illuminate 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 speed between the input side (engine speed) and output side (input turbine speed) of the torque converter when the ECM commands lock-up.

  (Engine speed is at least 170 rpm more than the input turbine speed.)

• There is no difference in rotation speed between the input side (engine speed) and output side (input turbine speed) of the torque converter when the ECM commands lock-up off.

  (The difference between engine speed and input turbine speed is less than 35 rpm.)