P0481

P0481

Fan control output stage 2 - open circuit/below limit value/above limit value

Diagnostic conditions
- Time after the engine is started longer than 10 seconds

Possible cause of fault
- Break in wiring in power supply to fan module 2 (small/to the left)
- Short circuit to ground in control line to fan module 2
- Short circuit to B+ in control line to fan module 2
- Fan module control module 2 faulty
- DME control module faulty

Affected terminals
DME control module connector B, pin 104, and fan connector 2, pin 3
Fan connector 2 pin 1, 2, and 4

Diagnosis/troubleshooting

WARNING:
Danger of injury.
When this fault occurs, the fan could suddenly start up with the ignition switched on. Bear the following points in mind to avoid risk of injury:
- Only work on the fan with the ignition switched off.
- Have a second person prevent the ignition from being accidentally switched on.

WARNING:
Danger of injury.
In the following instructions, it is recommended to connect another fan as a test step. Bear the following points in mind to avoid risk of injury:
- Connect the new fan so that objects cannot come into contact with it (body parts, hair, clothing, tools...)
- Only when this is done should the fan connector be connected.
- Have another person switch on the ignition
- When the diagnosis is finished, switch off the ignition and then disconnect the connector from the new fan

Fan 2 connector assignment (small/to the left)

Output stage for fan control 2

NOTE:
- The diagnosis monitors the fan module control line.
- Using a PWM ground signal, the DME sends a request to the control module integrated into the fan module. This request is acknowledged on the same line (feedback to the DME control module). If this feedback is not received, the fan goes into limp-home mode.
- The fan module cannot be tested from the input side.