P0A05

The actuation of the circulation pump for the low-temperature circuit has an open circuit.


Possible cause:

- M13/8 (Power electronics circulation pump)
Affected functions:

- Engine diagnosis
- Engine output

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Test 1: Check component M13/9 (Power electronics circulation pump 2).

1. Check component M13/9 (Power electronics circulation pump 2).

Test 1.1: Check component M13/9 (Power electronics circulation pump 2) by means of actuation.

Test 1.2: Check power supply of component M13/9 (Power electronics circulation pump 2).

Test 1.3: Check component K108/1 (Power electronics circulation pump relay 2).

1.1. Check component M13/9 (Power electronics circulation pump 2) by means of actuation.
Test prerequisite

- Switch on ignition.
- Actuate component M13/9 (Power electronics circulation pump 2).(Move on to actuation with button F2)
Figure legend

- B10/13 (Low-temperature circuit temperature sensor)
- M13/8 (Power electronics circulation pump 1)
- M13/9 (Power electronics circulation pump 2)
- N83/1 (DC/DC converter control module)
- N129/1 (Power electronics control unit)







Warning!Communication with ECU required.


1.2. Check power supply of component M13/9 (Power electronics circulation pump 2).
Test prerequisite

- Actuation is not OK.
Test sequence

- Switch off ignition.
- (M13/9) Measure direct voltage with multimeter between 2 and 1 (M13/9)
- Switch on ignition.
- Proceed to 'Actuation' with F2
Specified value

- Voltage[11.0...15.0] V


Warning!Communication with ECU required.


1.3. Check component K108/1 (Power electronics circulation pump relay 2).
Figure legend

- A -ConnectionTest cable 35-pin socket box
- 001 -Sockets of component N3/10 (ME-SFI [ME] control unit)
- 05 -35-pin socket box
- 050 -126-pin socket box
- 108 -Test cable 266 589 01 63 00
- N3/10 (ME-SFI [ME] control unit)
- II 1-63ConnectionTest cable
- III 64-126ConnectionTest cable
Warning!

- Connection A of test cable 108 may NOT be connected to connection B of the 126-pin socket box (050).
Continue to test with button F2







Test prerequisites

- Actuation of component M13/9 (Power electronics circulation pump 2) is not OK.
Test sequence

- Measure direct current with multimeter between socket [F.2] 98 of the 126-pole socket box tester and socket [F.44] 14 of the 35-pole socket box tester.
- Switch on ignition.
Specified value

- Amperage[0.1...0.3] A
- Component M13/9 (Power electronics circulation pump 2) is switched on and is heard to run.
Question

- Is the measurement value OK?


YES
The measurement value is OK.Further possible causes of fault

- M13/9 (Power electronics circulation pump 2)
End of test

NO
The measurement value is not OK.Possible cause and remedy

- Lines to component K108/1 (Power electronics circulation pump relay 2)
- Check voltage supply lines of component K108/1 (Power electronics circulation pump relay 2) as per wiring diagram.
- K108/1 (Power electronics circulation pump relay 2)
End of test