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Engine Coolant Temperature Signal For A/T

PURPOSE
When the engine coolant temperature is lower than 25°C (77°F) the switch in ECM turns ON to cause A16 circuit to be grounded. When it is higher than 30°C (86°F), the switch turns OFF to open the circuit.

The transmission control module uses it to control the A/T (Torque converter clutch (Lock-up) and overdrive systems).