Theory Of Operation

WARNING: This page is about a different variant/trim than selected.

The primary purpose of transmission thermal management system is to keep the Transmission fluid at its optimal operating temperature range. This is accomplished by directing coolant flow not required for cabin heat to the Thermal Management Unit (TMU) located on the left hand side of the Transmission which transfers heat from the engine coolant to the transmission oil fluid. Coolant flow is directed by means of the Coolant Three Way Valve located upstream of the cabin heater coolant supply. The coolant that is sent from the Coolant Three Way Valve warms the transmission fluid in order to get it up to the ideal operating temperature range quicker.

The Coolant Three Way Valve is supplied Battery voltage and a ground circuit. The Coolant Three Way Valve position is electrically controlled using a 12 volt PWM high side signal from the Powertrain Control Module (PCM). The PCM will send a PWM signal of 25% or 75% to the Coolant Three Way Valve, depending on whether the coolant is desired to be directed to the Heater Core or the TMU. The Coolant Three Way Valve has an internal position sensor that sends a signal back to the PCM. The sensor operates as a typical three wire sensor which has a 5-Volt Supply circuit, Signal circuit, and Return circuit.