Monitor Description

Torque converter lock-up is controlled by the ECM based on speed sensor NT, speed sensor NC, engine speed, engine load, engine temperature, vehicle speed, ATF 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 counter gear speed (NC). When conditions are appropriate, the ECM requests "lock-up" by applying control voltage to shift solenoid valve SL. When shift solenoid valve SL is turned on, it applies pressure to the lock-up relay valve and locks the torque converter.

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 shift solenoid valve SL or lock-up system performance. The ECM will turn on the MIL and store the DTC.

HINT: 

Example:

When the following is met, the system judges it to be 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 70 rpm more than the input turbine speed.)