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Fig. 2: Engine Cooling Schematic - Diesel DIAGNOSTIC INFORMATION AND PROCEDURES DIAGNOSTIC CODE INDEX DIAGNOSTIC CODE INDEX DTC P0480 OR P0481 Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach. DTC Description DTC P0480 or P0481 P0480: Cooling Fan Relay 1 Control Circuit DTC P1258 P1258: Engine Coolant Over temperature - Protection Mode Active
2008 Chevrolet Silverado 1500 2008 ENGINE Engine Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Diagnostic Procedure Instructions provide an overview of each diagnostic category. DTC Descriptor DTC P0480 Cooling Fan Relay 1 Control Circuit DTC P0481 Cooling Fan Relay 2 Control Circuit Diagnostic Fault Information Circuit/System Description The engine control module (ECM) commands the fans ON in either high speed or low speed, In low speed operation, the ECM applies ground to the coil side of the fan low relay. Voltage is In high speed operation, the ECM applies a ground to the coil side of the fan low relay, the fan The ECM monitors the low and high speed cooling fan relay control circuits for the following Short to ground Circuit Short to Ground High Resistance Open Short to Voltage Low Speed Cooling Fan Relay P0480 P0480 P0480 P0480 High Speed Cooling Fan Relay P0481 P0481 P0481 P0481
2008 Chevrolet Silverado 1500 2008 ENGINE Engine Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Short to voltage An open circuit If the ECM detects an improper voltage level on the low or high speed ECM driver circuits, then Conditions for Running the DTC The battery voltage is between 9-18 volts. The engine speed is greater than 400 RPM. Conditions for Setting the DTC The commanded state of the output driver module (ODM) and the actual state of the control The condition is present for more than 5 seconds. Action Taken When the DTC Sets DTCs P0480 and P0481 are Type B DTCs. Conditions for Clearing the MIL/DTC DTCs P0480 and P0481 are Type B DTCs. Diagnostic Aids This test procedure requires that the vehicle battery has passed a load test and is completely When disconnecting electrical connectors or removing fuses and relays from a fuse block, Use the J 35616 for any test that requires probing the underhood fuse block terminals, Reference Information Schematic Reference Engine Cooling Schematics Connector End View Reference
2008 Chevrolet Silverado 1500 2008 ENGINE Engine Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Component Connector End Views Electrical Center Identification Views Description and Operation Cooling Fan Description and Operation (w/o LFA) Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References Special Tools Required J 43244 Relay Puller Pliers J 35616 GM Approved Terminal Test Kit Circuit/System Verification 1. Ignition ON, command the cooling fan relay 1 ON and OFF several times using the scan tool output control function. You should hear both fans turn ON and OFF. Both should run 2. Ignition ON, command the cooling fan relays 2 and 3 ON and OFF several times using the scan tool output control function. When turned ON, the right fan should run on high and the 3. Ignition ON, command the cooling fan relays 1, 2, and 3 ON and OFF several times using the scan tool output control function. When turned ON, both fans should run on high speed. Circuit/System Testing
2008 Chevrolet Silverado 1500 2008 ENGINE Engine Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
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