Monitor Description

Torque converter lock-up is controlled by the ECM based on the speed sensor (NT), speed sensor (NC), engine speed, engine load, engine temperature, vehicle speed, transmission 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 RPM (NT). The ECM calculates the actual transmission gear by comparing the input turbine RPM (NT) to the counter gear RPM (NC). When conditions are appropriate, the ECM requests "lock-up" by applying control voltage to shift solenoid SL. When 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 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 70 RPM greater than the input turbine speed.)