P0493
DTC P0483 or P0493Circuit Description
The following DTCs are for the cooling fan.
- P0483 is for the difference of the commanded cooling fan speed compared to actual fan speed is greater than 1000 RPM.
- P0493 is for a cooling fan over speed condition, approximately 6800 RPM.
The cooling fan relay sends a pulse width modulation (PWM) signal of 12-14 volts to the cooling fan through the cooling fan clutch supply voltage circuit. The powertrain control module (PCM) uses this PWM signal in order to control the speed of the cooling fan. The signal controls the position of the oil control valve inside the cooling fan clutch. If the cooling fan RPM is different than the PCM is expecting, DTC P0483 will set. The actual cooling fan RPM vs the desired cooling fan RPM is not always exactly the same. There can be up to an 800 RPM difference. If the PCM detects that the cooling fan speed is over 6800 RPM then DTC P0493 will set.
Conditions for Running the DTC
- For DTC P0483:
- The engine is running.
- The system voltage is greater than 8.5 volts.
- The intake air temperature (IAT) is greater than -7°C (19°F).
- DTCs P0480 and P0526 are not set.
- The engine speed is less than 3200 RPM.
- The engine speed is not changing more than 250 RPM for 5 seconds.
- Fan command is greater than 0%.
- For DTC P0493 is that the engine is running.
Conditions for Setting the DTC
- For DTC P0483 is the difference between commanded and actual cooling fan speed is greater than 1000 RPM for 100 seconds.
- For DTC P0493 the cooling fan RPM is greater than 6800 RPM.
Action Taken When the DTC Sets
- For DTC P0483:
- The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
- The PCM will store the conditions as Freeze Frame/Failure Records data.
- The PCM commands the cooling fan to 100%.
- For DTC P0493:
- The Reduced Engine Power indicator illuminates.
- The PCM will store the conditions as Freeze Frame/Failure Records data.
Conditions for Clearing the MIL/DTC
The PCM turns OFF the MIL after the third consecutive trip that the diagnostic test has run and passed.
Diagnostic Aids
- An inline connector could cause an intermittent DTC. Ensure to test for poor connections and pin retention at all inline connectors.
- If the condition is not present, refer to Testing for intermittent and Poor Connections.
- Disconnect the harness connector of the cooling fan from the shroud. Inspect the exposed wires between the harness connector and the tubing.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step ensures that the DTC has failed this ignition cycle. If the scan tool displays Passed, then the answer is No.
3. The cooling fan noise should increase as the cooling fan engages. It can take up to 2 minutes for full cooling fan engagement. If cooling fan is previously fully engaged, then there will not be a noticeable change in cooling fan noise. Compare noise to a known good vehicle. If fan noise is louder than the known good vehicle, then answer Yes.
4. In the previous step the cooling fan was fully engaged. This step tests to ensure that the cooling fan will disengage. A noticeable noise difference should be heard between a fully engaged cooling fan and a disengaged cooling fan. The cooling fan is completely disengaged when the excessive fan noise is not heard.
5. Tests the PCM's ability to control the cooling fan. If answer to question is Yes, ensure to refer to all Diagnostic Aids.
6. Inspect for a mechanical condition which causes the DTC to set.
7. Tests for voltage on the cooling fan clutch supply voltage circuit of the cooling fan. The cooling fan connector is a seal connector. You must use jumper wires for testing or damage to wiring or connector could happen.
8. Tests the cooling fan relay for a PWM signal on the cooling fan clutch supply voltage circuit of the cooling fan.
DTC P0483 or P0493
