Monitor Description

Torque converter lock-up is controlled by the ECM based on the turbine (input) speed sensor NT, output 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 speed (NT). The ECM calculates the actual transmission gear by comparing input turbine speed (NT) to output shaft speed (NC). When conditions are appropriate, the ECM requests "lock-up" by applying control voltage to shift solenoid SLU. When SLU is turned on, it 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 shift solenoid valve SLU or lock-up system performance.

The ECM will illuminate the MIL and store this DTC.

Example:

When any of the following conditions are 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 input turbine speed.)