Porsche 944 Dme Relay Wiring Diagram

Pin assignment of DME control unit plug

Note

Slots marked black are not used.

1 Ignition coil

2 Ground, ignition output stage (MP IX)

3 Ground (Fuel pump relay)

4 Idle speed positioner, opening winding

5 not used

6 Speed signal at rev counter

7 Air mass sensor signal

8 Hall sender signal

9 Speed signal from speedometer

10 Ground, electronics (MP VIII)

11 Knock sensor 1

12 Positive terminal, Hall sender / throttle

13 Diagnostics L-wire

14 Ground, injection valves (MP IX)

15 not used

16 Injection valve cylinder 3

17 Injection valve cylinder 1

18 Terminal 30

19 Ground, electronics

20 not used

21 Check Engine warning lamp

22 Idle speed positioner, closing winding

23 VarioCam

24 Ground of remaining output stages (MP IX)

25 Hot-wire burnoff

26 Ground, air mass sensor

27 Terminal 15

28 Oxygen sensor/idle CO potentiometer

29 Knock sensor 2

30 Ground NTC/shield knock sensor

31 Knock yes/no

32 Control of AC relay

DME-Dlagnosls/Troubleshootlng

Printed in Germany - III, 1991

Diagnosis not practicable

Poor hot starting

Engine hesitation

Poor energie power

High fuel consumption

Misfiring

Poor pick-up

Erratic idling

Engine hard to start

Engine will not start

Test point

Engine in perfect running condition Battery charged Starter motor cranks the engine Terms in bold letters = Display Fault Memory / Fault Path

Fault Code 1

Test equipment

Plug, control Unit

X

X

X

X

1

Supply voltage

11

V

24 —» 18 24 —> 27

X

X

X

X

X

X

X

2

Engine temperature sensor 2

14

£2

45 —» 30

X

X

X

3

Throttle potentiometer

16

V

X

X

4

Oil temperature sensor

17

a

47->30

X

X

X

X

X

X

5

Rpm signal

18

=

49 —» 48

6

Speed signal <• Speedometer

19

=

9->24

X

X

X

X

X

X

X

7

Air flow sensor

21

vn

X

X

X

X

8

Oxygen regulation

23

X

X

X

X

9

Oxygen sensor

24

V

10

ignition timing change

26

X

X

X

11

Opening winding of idle stabilizer

27

V

X

X

X

12

Closing winding of idle stabilizer

28

V

13

Activation of AC relay

29

V n

X

X

X

14

Knock sensor 1

31

X

X

X

15

Knock sensor 2

32

X

X

X

16

Control unit faulty

33

-1

i

X

X

X

15

Knock sensor 2

32

X

X

X

16

Control unit faulty

33

X

X

X

17

Hall signal

34

=

X

X

X

18

VarioCam

35

V

19

Idle CO potentiometer

36

X

X

X

20

Control unit faulty

41

X

21

Fuel pump relay (DME-relay)

42

V

x

X

X

X

X

22

Tank ventilation relay

43

V =

23

Check Engine warning lamp

45

X

X

X

X

X

X

X

24

Injection valve cylinder 1

51

Vfl

X

X

X

X

X

X

X

25

Injection valve cylinder 2

52

Vi)

X

X

X

X

X

X

X

26

Injection valve cylinder 3

53

Vil

X

X

X

X

X

X

X

27

Injection valve cylinder 4

54

V £1

X

X

X

X

X

X

X

X

X

28

Fuel pressure

X

X

X

X

X

X

X

X

X

29

Intake system leaks

X

X

X

X

X

X

30

Ground and plug connections

X

X

X

X

X

X

X

X

X

31

Ignition system

=

X

X

32

Alternator + Regulator

V

x

33

Leads K + L

V

V = Voltmeter C2 = Ohmmeter = = Oscilloscope

V = Voltmeter C2 = Ohmmeter = = Oscilloscope

33 Tank venting valve

34 Injection valve cylinder 2

35 Injection valve cylinder 4

36 DME relay 85

37 DME relay 87

38 not used

39 not used

40 AC switch input

41 Coolant temperature switch (115'C)

42 Position switch (selector lever)

43 not used

44 Ground, version coding

45 Engine temperature sensor 2

46 not used

47 Oil temperature sensor

48 Speed signal / reference mark

49 Speed signal / reference mark

50 not used

51 Ignition angle cut-in (Tiptronic)

52 Throttle position to transmission control unit

53 Signal from throttle potentiometer

54 Version coding

55 Diagnosis for lead K

DME-Dlagnosis/Troubleshooting Printed in Germany - III, 1991

Fault, Fault Code Possible Causes, Elimination, Remarks Test Point 1a

Power supply for a) Permanent positive (B+ ) If there is no B+ the fault

DME control unit (V) memory is cleared

Test procedure:

Connect a voltmeter to terminal 24 (-) and terminal 18 (+) of the control unit plug with the help of test leads.

Display: Battery voltage

No display: Check current flow and ground paths in accordance with wiring diagram.

Test point 1 b Power supply of

DME control unit (V) too high/too low

Fault code 1 11

b) Power supply via terminal 15

Check regulator voltage with the engine running. Specified value approx. 13.8 V

Connect a voltmeter to terminal 24 (-) and terminal 27 (+) of the control unit plug with the help of test leads. Turn on ignition.

Display: Battery voltage

No display: Check current flow according to wiring diagram

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Fault, Fault Code Possible Causes, Elimination, Remarks Test point 2

Engine temp, sensor Using System Tester 9288, the engine temperature can be read off

(NTC ll/ii) directly in menu item „Actual values".

Fault code 1_14 no is not p|ausib|e display:

Connect ohmmeter to terminal 45 and terminal 30 of the disconnected DME control unit plug with the help of test leads.

If the above values are not obtained, check directly at engine temperature sensor.

Note: Temperature sensor 2 informs the control unit of the engine temperature. It provides additional fuel in the cold starting and warm-up stages of engine operation.

Open circuit ii):

The DME control unit of the 968 adjusts to a value pre-set in the control unit that approximately corresponds to that of the engine at operating temperature. Enrichment by the faulty temperature sensor 2 when the engine is warm does not occur (emergency running program). This results in starting problems when the engine is cold (no cold start enrichment).

Short circuit to ground:

When engine is cold: No engine pickup, too lean, engine stops. No effect if engine is at operating temperature.

Replacement value is applicable to both types of fault!

Fault, Fault Code Possible Causes, Elimination, Remarks

Continue reading here: Test point

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