Circuit/System Description
The engine control module (ECM) commands the fans ON in high speed or low speed. In low speed, the fans are configured in series. In high speed, the fans are configured in parallel.
In low speed operation, the ECM applies ground to the coil side of the low speed relay. Voltage is applied directly to the left cooling fan through the switch side of the low speed relay. The right fan is connected in series to the left fan through the de-energized series/parallel relay so that both fans operate at low speed.
In high speed operation, the ECM applies a ground to the coil side of the low speed relay, the series/parallel relay, and the high speed relay. Voltage is applied directly to the right cooling fan through the switch side of the high speed relay. The left cooling fan obtains voltage through the low speed relay and ground through the series/parallel relay.
When the ECM is commanding a fan relay ON, the voltage of the control circuit should be low, near 0 volts. When the ECM is commanding a fan relay OFF, the voltage of the control circuit should be high, near battery voltage.
Circuit/System Description (V6)
The engine control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.
In low speed operation, the ECM applies ground to the coil side of the low speed fan relay. This energizes the coil and applies voltage directly to the left cooling fan through the switch side of the relay. The left fan is connected in series to the right cooling fan through the de-energized series/parallel (S/P) fan relay. The series circuit operates both fans at low speed.
In high speed operation, the ECM applies a ground to the coil side of the low speed fan relay, the S/P fan relay, and the high speed fan relay. When energized, the high speed fan relay applies voltage directly to the right cooling fan through the switch side of the relay. Simultaneously, the low speed fan relay and the S/P fan relay provide ignition voltage and a direct path to ground for the left cooling fan. With both fans connected in a parallel circuit, each fan receives full voltage and operates at high speed.
The engine control module (ECM) uses the engine coolant temperature (ECT) sensor to monitor the engine for an over-termperature condition. This condition occurs when the coolant temperature is above a calibrated value for a calibrated length of time. The ECM will disable half of the cylinders by turning OFF the fuel injectors. By disabling half of cylinders, the ECM is able to reduce the temperature of the coolant.
Circuit/System Description (with RPO LC3 or LH2)
The engine control module (ECM) uses the engine coolant temperature (ECT) sensor to monitor the engine for an overtermperature condition. This condition occurs when the coolant temperature is above a calibrated value for a calibrated length of time. The ECM will disable half of the cylinders by turning OFF the fuel injectors. By disabling half of cylinders, the ECM is able to reduce the temperature of the coolant.
The auxiliary coolant pump system provides a measure of prevention against fuel vaporization due to excessive engine temperatures. The engine control module (ECM) commands the auxiliary or after boil coolant pump ON when the engine coolant temperature exceeds a calibrated value after engine shut down. The ECM applies ground to the coil side of the auxiliary pump relay. This energizes the coil and applies voltage directly to the pump motor through the switch side of the relay.
The engine control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.
In low speed operation, the ECM applies ground to the coil side of the low speed fan relay. This energizes the coil and applies voltage directly to the left cooling fan through the switch side of the low relay. The left fan is connected in series to the right cooling fan through the de-energized series/parallel (S/P) fan relay. The series circuit operates both fans at low speed.
In high speed operation, the ECM applies a ground to the coil side of the low speed fan relay, the S/P fan relay, and the high speed fan relay. When energized, the high speed fan relay applies voltage directly to the right cooling fan through the switch side of the relay. Simultaneously, the low speed fan relay and the S/P fan relay provide ignition voltage and a direct path to ground for the left cooling fan. With both fans connected in a parallel circuit, each fan receives full voltage and operates at high speed.
The engine control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.
In low speed operation, the ECM applies ground to the coil side of the low speed fan relay. This energizes the coil and applies voltage directly to the left cooling fan through the switch side of the low relay. The left fan is connected in series to the right cooling fan through the de-energized series/parallel (S/P) fan relay. The series circuit operates both fans at low speed.
In high speed operation, the ECM applies a ground to the coil side of the low speed fan relay, the S/P fan relay, and the high speed fan relay. When energized, the high speed fan relay applies voltage directly to the right cooling fan through the switch side of the relay. Simultaneously, the low speed fan relay and the S/P fan relay provide ignition voltage and a direct path to ground for the left cooling fan. With both fans connected in a parallel circuit, each fan receives full voltage and operates at high speed.
The engine control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.
In low speed operation, the ECM applies ground to the coil side of the low speed fan relay. This energizes the coil and applies voltage directly to the left cooling fan through the switch side of the low relay. The left fan is connected in series to the right cooling fan through the de-energized series/parallel (S/P) fan relay. The series circuit operates both fans at low speed.
In high speed operation, the ECM applies a ground to the coil side of the low speed fan relay, the S/P fan relay, and the high speed fan relay. When energized, the high speed fan relay applies voltage directly to the right cooling fan through the switch side of the relay. Simultaneously, the low speed fan relay and the S/P fan relay provide ignition voltage and a direct path to ground for the left cooling fan. With both fans connected in a parallel circuit, each fan receives full voltage and operates at high speed.
The engine control module (ECM) commands the fans ON in high speed or low speed. In low speed, the fans are configured in series. In high speed, the fans are configured in parallel.
In low speed operation, the ECM applies ground to the coil side of the low speed relay. Voltage is applied directly to the left cooling fan through the switch side of the low speed relay. The right fan is connected in series to the left fan through the de-energized series/parallel relay so that both fans operate at low speed.
In high speed operation, the ECM applies a ground to the coil side of the low speed relay, the series/parallel relay, and the high speed relay. Voltage is applied directly to the right cooling fan through the switch side of the high speed relay. The left cooling fan obtains voltage through the low speed relay and ground through the series/parallel relay.
When the ECM is commanding a fan relay ON, the voltage of the control circuit should be low, near 0 volts. When the ECM is commanding a fan relay OFF, the voltage of the control circuit should be high, near battery voltage. If the ECM detects that the actual voltage of the relay control circuit is different than the expected voltage, DTC P0480 or P0481 will set and the affected ECM driver will be disabled.
The auxiliary coolant pump system provides a measure of prevention against fuel vaporization due to excessive engine temperatures. The engine control module (ECM) commands the auxiliary or after boil coolant pump On when the engine coolant temperature exceeds a calibrated value. The ECM applies ground to the coil side of the auxiliary pump relay. This energizes the coil and applies voltage directly to the pump motor through the switch side of the relay.
The auxiliary coolant pump system provides a measure of prevention against fuel vaporization due to excessive engine temperatures. The engine control module (ECM) commands the auxiliary or after boil coolant pump On when the engine coolant temperature exceeds a calibrated value. The ECM applies ground to the coil side of the auxiliary pump relay. This energizes the coil and applies voltage directly to the pump motor through the switch side of the relay.
The auxiliary coolant pump system provides a measure of prevention against fuel vaporization due to excessive engine temperatures. The engine control module (ECM) commands the auxiliary or after boil coolant pump On when the engine coolant temperature exceeds a calibrated value. The ECM applies ground to the coil side of the auxiliary pump relay. This energizes the coil and applies voltage directly to the pump motor through the switch side of the relay.
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.