P0480

DTC P0480: Cooling Fan Relay 1 Control Circuit

Wiring Diagram:

Circuit Description
Ignition voltage is supplied directly to the cooling fan relay coil. The Engine Control Module (ECM) controls the relay by grounding the control circuit via an internal switch called a driver. The primary function of the driver is supply the ground for the component being controlled. Each driver has a fault line which is monitored by the ECM. When the ECM is commanding a component ON, the voltage of the control circuit should be low (near 0 V). When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the Diagnostic Trouble Code (DTC) to set.
The relay is used to control the high current flow to the cooling fan motors. This allows the ECM driver to only have to handle the relatively low current used by the relay.

Conditions for Setting the DTC
- Ignition ON.
- An open, a short to ground or a short to battery condition in the low speed cooling fan control circuit exists.
- Ignition voltage is between 11 and 16 V.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- The MIL will turn OFF after four consecutive validation cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 40 consecutive warm up cycles without a fault.
- The DTC(s) can be cleared by using the scan tool.

Diagnostic Aids
Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and/or Failure Records data can be useful in determining how many miles since the DTC set. The fail counter and pass counter can also be used to determine how many ignition cycles the diagnostics reported a Freeze Frame conditions (RPM, load, vehicle speed, temperature, etc.) that are noted.
This will isolate when the DTC failed.

Step 1-3:

Step 4-13:

Troubleshooting