Electric Thermostat With Heater Element
| ITEM | DESCRIPTION |
|---|---|
| 1 | Hose connection - Engine outlet |
| 2 | Hose connection - Turbocharger, heater core and Transmission fluid coolant return |
| 3 | Hose connection - Coolant expansion tank |
| 4 | Hose connection - Radiator lower hose |
| 5 | Electrical connector - Heater element |
| 6 | Hose connection - Variable coolant pump |
The electric thermostat contains a wax heating element. When energized, the heater element heats the wax element, partially controlling the thermostat function along with engine coolant temperature control. Operation is therefore activated not only by the engine coolant temperature, but as specified by the Powertrain Control Module (PCM). This enables a finer control of the opening and closing of the electric thermostat.
The wax provides higher engine coolant temperature during part load conditions and at low speed cycles. The increased engine coolant temperature results in reduced friction in the engine, improved combustion in the cylinders and reduced fuel consumption and emissions. The electric thermostat heater element assembled within the wax element, pulls down the engine coolant temperature during high load conditions and speed points. This protects the engine from thermal overload.
Opening of the electric thermostat is at a temperature of 101°C +/- 2°C (213°F +/- 4°F).
Operation of the electric thermostat is controlled by the PCM upon the following inputs:
- Engine coolant set point (°C)
- Engine speed (rpm)
- Torque (Nm)
- Terrain Mode position (Normal, Sand, Rock, etc)
- Cylinder block temp (°C)
- Environmental temp (°C)
- Radiator bottom hose temp (°C)
- Air mass flow (Kg/h)
The electric thermostat has a power feed from the Engine Junction Box (EJB), a switched power supply from the PCM relay. The electric thermostat is also provided with a hardwired connection to the PCM and a ground connection. When the PCM starts to regulate the system, the PCM supplies a ground path for the heater element in the electric thermostat. This causes the wax element to expand and increase the stroke of the main valve, opening the radiator flow route.