Monitor Description

Torque converter lock-up is controlled by the ECM based on the transmission revolution sensor (NT and NC), engine speed, engine load, engine temperature, vehicle speed, ATF temperature and gear selection signals. The ECM determines the lock-up status of the torque converter assembly by comparing the engine speed (NE) to the transmission revolution sensor (NT) signal. The ECM calculates the actual gear by comparing the transmission revolution sensor (NT) signal to the transmission revolution sensor (NC) signal. When conditions are appropriate, the ECM requests "lock-up" by applying voltage to the solenoid (SLU) valve. When the solenoid (SLU) valve is turned on, pressure is applied to the lock-up relay valve and locks the torque converter assembly.

If the ECM does not detect lock-up after lock-up has been requested or if it detects lock-up when it is not requested, it interprets this as a malfunction of the solenoid (SLU) valve, illuminates the MIL and stores this DTC.

HINT: 

Example:

When any of the following is met, the system judges it as a malfunction.

• There is a difference in speed between the input side (engine speed) and output side (input turbine speed) of the torque converter assembly when the ECM commands lock-up. (Engine speed is at least 170 rpm more than input turbine speed.)
• There is no difference in speed between the input side (engine speed) and output side (input turbine speed) of the torque converter assembly when the ECM commands lock-up off. (The difference between engine speed and input turbine speed is less than 35 rpm.)