Electric Thermostat
| ITEM | DESCRIPTION |
|---|---|
| 1 | Hose connection - Radiator upper hose |
| 2 | Hose connection - Electric throttle |
| 3 | Heater element |
| 4 | Hose connection - Heater core |
| 5 | Hose connection - Radiator bypass |
| 6 | Engine coolant temperature sensor |
| 7 | Cylinder block outlet connection |
The electric thermostat independently controls the engine coolant flow to the cylinder head and cylinder block, improving engine warm up times. The thermostat contains a wax expansion element that incorporates a heater element. When energized the heating element heats the wax element, partially controlling the thermostat function, along with engine coolant temperature control. Operation is therefore performed not only by the engine coolant temperature, but as specified by the PCM . This enables a finer control of the opening and closing of the electric thermostat. Opening of the electric thermostat is at a temperature of 90°C +/- 2°C (194°F +/- 4°F).
The electrically heated thermostat is used to regulate the engine coolant temperature by the PCM . The increased wax temperature 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. An electric thermostat heater element assembled within the wax element to regulate the engine coolant temperature during high load conditions and speed points. This protects the engine from thermal overload.
Operation of the electric thermostat is controlled by the PCM upon the following inputs:
- Engine load
- Engine speed
- Vehicle speed
- Engine coolant temperature
- Intake air temperature.
The electric thermostat has a battery feed from the Engine Junction Box (EJB), a switched power supply from the PCM relay. It is also provided with a hardwired connection to the PCM and a ground connection. If the PCM starts to regulate the system, the PCM supplies a ground path for the heater element in the electric thermostat. This causes the element to expand and increase the opening dimension of the electric thermostat.