Radiator Shutter Circuit Description LG5
The ENG Circuit Breaker supplies voltage to the load side of the Ignition Relay.
The IGN 1 Circuit Breaker supplies control voltage to the Ignition Relay. The Ignition Relay is energized when the Ignition Switch is turned to the START or the RUN position. The Ignition Relay then supplies voltage through CKT 639 (PNK) to the Radiator Shutter Control Valve. Current flows through the control valve through CKT 36 (LT GRN) to the Radiator Shutter Engine Coolant Temperature Sensor.
When the coolant temperature is below 90.6°C (195°F) the sensor remains closed. When the sensor is closed, current is allowed to flow through the sensor ground to CKT 150 (BLK), completing the circuit. Either air pressure or oil pressure then flows through the Radiator Shutter Control Valve in order to close the Radiator Shutter.
The coolant sensor monitors the engine coolant temperature. The coolant sensor opens when the coolant temperature reaches 90.6°C (195°F).
The following actions occur when the sensor opens:
| • | The circuit opens. |
| • | The Radiator Shutter Control Valve closes. |
| • | The air pressure or the oil pressure is bled off. |
| • | The Radiator Shutters open. |
Radiator Shutter Circuit Description GM Diesel
The IGN 1 Circuit Breaker supplies voltage to the Radiator Shutter Control Valve Relay when the Ignition Switch is in the START or the RUN position.
The Engine Control Module (ECM) monitors the engine coolant temperature signal that is received from the Engine Coolant Temperature Sensor. The ECM then grounds the coil side of the Radiator Shutter Control Valve Relay. When the relay is energized, voltage is available at the Radiator Shutter Control Valve through CKT 999 (YEL).
The following actions occur because the control valve is permanently grounded by CKT 150 (BLK):
| • | The Radiator Shutter Control Vale is energized. |
| • | The Radiator Shutters close. |
The following actions occur when the engine coolant temperature reaches 90.6°C (195°F):
| • | The ECM removes the ground from the control side of the relay. |
| • | The Radiator Shutter Control Valve de-energizes. |
| • | The Radiator Shutters open. |
