Troubleshooting

DTC P0743 Torque Converter Clutch Circuit Electrical

CIRCUIT DESCRIPTION

DTC Detecting Condition:

The shift solenoid valve SL is turned ON and OFF according to signals from the ECM to control the hydraulic pressure acting on the lock-up relay valve, which then controls operation of the lock-up clutch.

Fail-safe function:
If the ECM detects a malfunction, it turns the shift solenoid valve SL OFF.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

Torque converter lock-up is controlled by the ECM based on engine rpm, engine load, engine temperature, vehicle speed, transmission temperature, and shift range selection. The ECM determines the lock-up status of the torque converter by comparing the engine rpm (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 valve SL. When opened, solenoid SL applies pressure to the lock-up relay valve and locks the torque converter clutch. If the ECM detects an open or short in the SL solenoid circuit, the ECM interprets this as a fault in the solenoid valve SL or its circuit. The ECM will turn on the MIL and store the DTC.

Wiring Diagram:

Step 1:

Step 2 - 3:

INSPECTION PROCEDURE