P0481

P0481

Diagnosis information - DME V6 DFI

Driver for fan control 2

WARNING:
Danger of injury:
If this fault occurs, the fan may already start when the ignition is switched on. The following points must be observed in order to exclude the risk of injury:
- Perform work on the fan only with the ignition switched off.
- Secure the ignition to prevent accidental switching on by other persons.

WARNING:
Danger of injury:
In the following instructions, trial connection of a different fan is recommended as a test step.
The following points must be observed in order to exclude the risk of injury:
- Fit the new fan so that no objects can become caught up in it (parts of the body, hair, clothing, tools, etc.)
- Only then connect the fan connector.
- Assign the task of switching on the ignition to another person
- When diagnosis has been completed, switch off the ignition and disconnect the connector of the new fan again

NOTE:
Diagnosis monitors control of the fan module.
The DFI sends a request to the control unit integrated in the fan module via this line by means of a pulse-width-modulated ground signal. This request is acknowledged on the same line (feedback to the DFI control unit). The fan switches to emergency operating mode if this feedback is not received.
The fan module cannot be measured on the input side.

Diagnostic conditions
- Time after engine starts greater than 10 seconds

Possible fault causes
- Open circuit in power supply line to fan module 2 (small / left)
- Short circuit to ground in control line to fan module 2
- Short circuit to B+ in control line to fan module 2
- Control unit of fan module 2 faulty

Affected contacts on the DFI control unit connector
Connector [B]:
- Contact 30

Affected contacts on connector of fan 2
Connector [A]:
- Contact 3
- Contact 1
- Contact 2
- Contact 4