Circuit/System Description
The engine control module (ECM) sends a pulse width modulation (PWM) signal of 0-12 volts via the cooling fan clutch control circuit to the cooling fan relay. The ECM monitors the cooling fan clutch control circuit during vehicle operation. When the cooling fan is commanded on by the ECM, the control circuit is at a low voltage. When the cooling fan is commanded off, the control circuit is near battery voltage. The ECM uses this PWM to control the position of the oil control valve located inside the cooling fan clutch.
The cooling fan relay sends a pulse width modulation (PWM) signal of 12-14 volts to the cooling fan clutch through the cooling fan clutch supply voltage circuit. The engine control module (ECM) uses this PWM signal in order to control the speed of the cooling fan clutch. The signal controls the position of the oil control valve inside the cooling fan clutch.
The cooling fan relay sends a pulse width modulation (PWM) signal of 12-14 volts to the cooling fan by the cooling fan clutch supply voltage circuit. The engine control module (ECM) uses the PWM signal, which controls the speed of the cooling fan clutch by controlling the position of the oil control valve inside the clutch. If the cooling fan clutch RPM is too high when the control module is commanding 0 percent, DTC P0495 will set.
The engine control module (ECM) uses the cooling fan speed signal in order to determine the actual fan speed in relation to the desired fan speed. The ECM uses the cooling fan speed signal in order to reduce the cooling fan noise and in order to maintain the powertrain cooling requirements. The ECM supplies power and ground to the clutch hall effect sensor of the cooling fan clutch. The hall effect sensor returns a signal pulse through the speed signal circuit in response to the reluctor track, which is located inside the fan clutch.
The low engine coolant level indicator is controlled by the engine control module (ECM). The normal state of the engine coolant level switch is closed when in contact with coolant.
The optional coolant heater operates using 110 volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather. There is an internal thermal switch in the power cord that prevents operation above -18°C (0°F). The coolant heater helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. A weather shield on the cord is provided to protect the plug when not in use.
Reference Information
The optional coolant heater operates using 110 volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather. There are two heater cords available. One has an internal thermal switch in the power cord that prevents operation above -18°C (0°F) and the other operates at all temperatures. A weather shield on the cord is provided to protect the plug when not in use.