• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Cooling Fan Relay Control Circuit | P0480 | P0480 | P0480 | -- |
Cooling Fan Relay Coil Voltage Supply Circuit | P0480 | P0480 | -- | -- |
The engine cooling fan system consists of one cooling fan and one relay. The relay is powered by the battery positive voltage circuit and controlled by a switched ground from the engine control module (ECM).
During operation, the ECM supplies the ground path for the cooling fan relay, which is relay 1, through the cooling fan relay control circuit. This energizes the cooling fan relay coil, closes the relay contacts, and supplies battery positive voltage from the cooling fan fuse through the cooling fan motor supply voltage circuit to the cooling fan. The cooling fan motor is grounded through its own ground circuit.
• | The engine is running. |
• | The system voltage is between 11-18 volts. |
• | The relay control circuit is transitioned from OFF to ON, or ON to OFF. |
• | An improper voltage level has been detected on the cooling fan relay control circuit. |
• | The condition must be present for a minimum of 30 seconds. |
DTC P0480 is a Type B DTC.
DTC P0480 is a Type B DTC.
Cooling Fan Description and Operation
Control Module References for scan tool information
Ignition ON, command the relay ON and OFF with a scan tool. Feel or listen to verify that the relay turns ON and OFF with each command.
⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the relay. |
⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
⇒ | If the cooling fan does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the cooling fan. |
⇒ | If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM. |
⇒ | If the resistance is not within the specified range, replace the relay. |
⇒ | If the DMM does not indicate the specified values, test the control circuit for an open or a short to voltage. If the circuit tests normal, replace the ECM. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.