• | 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 Speed Control | P1482 | P1482 | P1482 | -- |
Cooling Fan Motor Supply Voltage | -- | -- | -- | -- |
Cooling Fan Low Reference | -- | -- | -- | -- |
Battery Positive Voltage | -- | -- | -- | -- |
Ground | -- | -- | -- | -- |
The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated signal to the cooling fan speed control module. The cooling fan control module varies the voltage drop across the engine cooling fan motor in relation to the pulse width modulated signal. The cooling fan speed is affected by many different conditions and can be adjusted from 10 to 84 percent duty cycle (PWM). A duty cycle of 84 percent is considered high fan speed. When multiple cooling speed requests are received the ECM uses the highest cooling fan speed of all the requests. During normal fan ON operation the control circuit voltage will be low and near battery voltage when the fan is OFF.
• | The battery voltage is between 9-18 volts. |
• | The engine speed is greater than 400 RPM. |
• | The commanded state of the output driver module (ODM) and the actual state of the control circuit do not match. |
• | The condition is present for more than 5 seconds. |
DTCs P1482 is Type B DTCs.
DTCs P1482 is Type B DTCs.
Cooling Fan Description and Operation
• | Circuit Testing |
• | Wiring Repairs |
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
Important: Circuit/System Verification must be performed first or misdiagnosis may result.
⇒ | If the lamp is ON, test the cooling fan speed control circuit for a short to ground. If the circuit tests normal, replace the ECM. |
⇒ | If the lamp is OFF, test the cooling fan speed control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
⇒ | If the cooling fan does not activate, replace the cooling fan. |
⇒ | If the fan does not activate correctly, test the cooling fan speed control module voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, replace the cooling fan speed control module. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for ECM replacement, setup, and programming