2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 2204
Circuit/System Description
The hybrid engine cooling fan system consists of two electrical cooling fans, two resistors, three engine control module (ECM) fan control circuits,
and five fan relays. The relays are arranged in a series/parallel configuration that allows the ECM to operate the fans at low, medium, or high speed
depending on cooling requirements. The ECM controls the five relays by grounding the relay control circuits.
To operate the fans, the ECM activates the applicable relay by grounding the control circuit with a solid state device called a driver. The driver is
equipped with a feedback circuit. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the
feedback voltage. 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.
Conditions for Running the DTC
* The ignition voltage is between 11-32 volts.
* The engine speed is greater than 0 RPM.
* DTC P0480, P0481, and P0482 run continuously when the conditions above are met.
Conditions for Setting the DTC
* The commanded state of the ECM driver and the actual state of the control circuit do not match.
* The condition exists for greater than 5 seconds.
Action Taken When the DTC Sets
DTCs P0480, P0481 and P0482 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0480, P0481 and P0482 are Type B DTCs.
Diagnostic Aids
* The ECM has the capability of providing command to the fan relays even when a scan tool output control is being used. Always refer to the
fan control command parameters on the scan tool to know which fans are being commanded ON by the ECM.
* The scan tool cooling fan output control operates as follows:
- Fan Relay 1 operates both fans at a low speed.
- Fan Relay 2 operates both fans at medium speed.
- Fan Relays 1, 2, and 3 operates both fans at high speed.
Reference Information
Schematic Reference
Engine Cooling Schematics (See: Engine, Cooling and Exhaust/Cooling System/Diagrams)
Connector End View Reference
* Component Connector End Views (See: Diagrams/Connector Views)
* Powertrain Component Views (See: Locations/Component Locations/Powertrain Component Views)
* Electrical Center Identification Views (See: Maintenance/Fuses and Circuit Breakers/Fuse/Application and ID)
Description and Operation
Cooling Fan Description and Operation (Gas) (See: Engine, Cooling and Exhaust/Cooling System/Description and Operation/Cooling Fan
Description and Operation (Gas))
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
