Mportant

Fuel System - Electronic Control

911 Carrera 2 911 Carrera 4

1

Ignition pulse to output stage

27

2

Ground - output stage shield

28 29

3

DME relay ground f (fuel pump)

V

1

30

1

4

Idle speed control

. l*o 1

38

5

Tank venting valve

2

31

6

Engine speed to

1 1 21 1

39

32

tachometer

3

33

7

Signal from air flow

1 122 1

40

34

sensor

4

36

8

Signal from Hall sensor

, I" 1

41

9

5

10

Ground - oxygen

6

, 1" 1

42

37

11

sensor shield Knock sensor I

7

1 |25 1

43

38

12

Power supply,

, I" 1

44

39

air flow sensor

8

40

13

Lead L from diagnostic

1 127 1

45

42

plug

9

14

Ground

! i™ 1

46

43

15

ti signal, cyl. 3

10

44

16

ti signal, cyl. 6

, I" 1

47

45

17

ti signal, cyl. 1

11

46

18

Permanent positive

, |30 1

48

47

19

Ground

12

48

20

, |31 1

49

13

49

21

Diagnostic plug, knocking

, 1

50

yes + no

14

50

22

Check engine control

, |33 1

51

23

Resonance plate

15

51

24

Ground

, 134 1

52

52

25

16

1

1 I35 1

53

26

Ground for air flow meter

53

54

17

1

! |36 1

55

54

18

, 137 1

55

19

1

Oxygen sensor signal Knock sensor II Shield, for knock sensors, Hall sensor and ground for knock sensors Positive to Hall sensor Consumption gauge ti signal, cyl. 5 ti signal, cyl. 4 ti signal, cyl. 2

Voltage from DME relay with ignition

Version coding Air-conditioning compressor AC switch

Intake air temperature NTC I Engine temperature NTC II Altitude potentiometer Speed/reference mark positive Speed/reference mark negative shield

Heating/air-conditioning regulation

Idle signal - throttle valve Full load signal - throttle valve Coding plug, characteristic map Diagnostic plug, lead K

ftHTreöliriP5le 0f Contents

911 Carrera 4

cm cm cm m

co t

CO CO

g 55

CB.O

ra 0

co 0

iS c

Test point cm co m co co o cm co m co oo

ra ra c

Engine will not start

Engine hard to start

Erratic idling

Poor pick-up

Misfiring

High fuel consumption

Engine hesitation

Poor power output

Poor hot starting

Diagnosis not possible

Fault, Fault Code

Possible Causes, Elimination, Remarks

Test point 1a

Power supply for DME control unit (V)

a) Permanent positive (B+) If there is no B+, the fault 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 1b Power supply for DME

control unit (V) too high/too low Fault code 1 11

b) Power supply via DME relay

Connect a voltmeter to terminal 24 (-) and terminal 37 (+) of the control unit plug with the help of test leads. Turn on the ignition.

Display: Battery voltage

No display: Check current path in accordance with wiring diagram

Note:

Cars with burglar alarm: Check power supply from ignition lock to terminal 86 of the DME relay via the burglar alarm control unit in accordance with the wiring diagram.

Cars without burglar alarm: Check the plug jumpers on plug section (provided for installation of a burglar alarm control unit).

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