DME 7.2

P0481
495 Fan Output Stage 2 - Open Circuit

P0481
495 Fan Output Stage 2 - Below Limit

P0481
495 Fan Output Stage 2 - Above Limit

Function
Two two-stage electric fans are installed to keep the coolant cool. The electric fans are each triggered via two relays by the DME control module.

Diagnosis conditions
- Engine running
- Battery voltage greater than 7 V


NOTE: The triggering wire for relays stage 2 terminal 85, is monitored.

Wiring Diagram:

Open Circuit:

Short Circuit To Ground:

Short Circuit To B+:

1 Check both relays.

1. Remove relay.
2. Connect ohmmeter to terminals 85 and 86.
Display: approx. 75 ohms

2 Check wiring from DME control module, pin IV/20, to relays for continuity.

1. Connect special tool 9637 to wiring harness (DME control module connector).
2. Remove relay stage 2 of coolant fan 1.
3. Remove relay stage 2 of coolant fan 2.
4. Connect ohmmeter to special tool 9637, pin IV/20, and relay slot of coolant fan 1, pin 2 (terminal 85).
Display: 0 - 5 ohms
5. Connect ohmmeter to special tool 9637, pin IV/20, arid relay slot of coolant fan 2, pin 2 (terminal 85).
Display: 0 - 5 ohms

If infinity ohms is displayed, check connector X 2/3, pin 22, arid wiring harness for chafing and pinching damage.

3 Perform adaptation.

1. Switch on the ignition.
2. Wait one minute. Do not press the accelerator.
3. Switch off the ignition for at least 10 seconds.
4. Read out the fault memory.

4 Check wiring from DME control module, pin IV/20, to relays for short circuit to ground.

1. Connect special tool 9637 to wiring harness (DME control module connector).
2. Remove relay stage 2 of coolant fan 1.
3. Remove relay stage 2 of coolant fan 2.
4. Connect ohmmeter to special tool 9637, pin IV/20, and ground.
Display: infinity ohms

If 0 - 5 ohms is displayed, check wiring for chafing and pinching damage.

5 Check wiring from DME control module, pin IV/20, to relays for short circuit to B+

1. Connect special tool 9637 to wiring harness (DME control module connector).
2. Remove relay stage 2 of coolant fan 1.
3. Remove relay stage 2 of coolant fan 2.
4. Connect voltmeter to special tool 9637 pin IV/20, and ground.
Ignition on.
Display: 0 V

If battery voltage is displayed, check wiring harness for chafing and pinching damage.