Transaxle Temperature Sensor (Trans Temp)

The transaxle temperature sensor is used to control TCC and line pressure. The transaxle temperature sensor attaches to upper control valve assembly. See Figure . The sensor is a negative temperature coefficient thermistor which receives a five volt signal from PCM. When temperature is cold, sensor resistance is high; therefore PCM sees a high signal voltage. As fluid warms, sensor resistance decreases, voltage drop access sensor decreases so signal voltage will become lower. The transaxle temperature sensor may be tested with a Voltmeter across pin terminals C and D of 8-way transaxle connector. Nominal voltage readings at specified temperatures are given in Voltage levels at PCM.The transaxle temperature sensor has two modes of operation.

• Hot mode enable (Above 130°C [266°F]) - TCC On in 3rd at 30 mph, 0-10 degrees throttle angle and 4th at 39 mph, 0-10 degrees throttle angle - This reduces transaxle temperature by decreasing heat generated in torque converter. It also provides maximum cooling by routing transaxle fluid directly to transaxle cooler in engine radiator.
• Super-hot disable (270 HP RPO LD8 ENGINE) (Above 140°C [284°F]) - VCC Off, Inhibit operation of 4th - Super-hot is a condition where a hot engine adds heat to transaxle through transaxle cooler. By inhibiting VCC and 4th gear operation, engine works under less load. This reduces heat added to transaxle fluid by transaxle cooler. As both engine and transaxle cool off, VCC and 4th gear are permitted again.