MOTRONIC M 2.7 WIRING DIAGRAM

TERMINAL ASSIGNMENT OF WIRING HARNESS PLUG FOR MOTRONIC M 2.7 CONTROL UNIT K61

Terminal Assignment

Ter. 1       Final stage, ignition module K 20/Ter. 4

Ter. 2       Recognition ‑ 1 at gear S 53

Ter. 3       Ground actuation for fuel pump relay K 68 / Ter. 85 B

Ter. 4       Ground actuation for idle speed adjuster M 33

Ter. 5       Ground actuation for tank vent valve Y 34

Ter. 6       Unoccupied

Ter. 7       Signal, hot‑wire mass air flow meter P 44/Ter. 3

Ter. 8       Signal, Hall sensor cylinder recognition P 47/Ter. 2

Ter. 9       Signal, odometer frequency sensor P 21

Ter. 10     Ground Ter. 31

Ter. 11     Signal, knock sensor

Ter. 12     Voltage supply, Hall sensor P 47/Ter. 3; throttle valve potentiometer P 34/Ter. 1

Ter. 13     Diagnostic excitation lead, diagnostic plug X 1 3/Ter. B

Ter. 14     Ground Ter. 31

Ter. 15     Unoccupied

Ter. 16     Ground actuation for injection valve Y 7, cylinder 3

Ter. 17     Ground actuation for injection valve Y 7, cylinder 1

Ter. 18     Battery Ter. 30

Ter. 19     Ground Ter. 31

Ter. 20     Unoccupied

Ter. 21     Ground actuation for charge pressure bypass valve Y 12

Ter. 22     Ground actuation for engine telltale

Ter. 23     Unoccupied

Ter. 24     Ground Ter. 31

Ter. 25     Ground actuation for hot‑wire mass air flow meter P 44 / Ter. 4, 'burn‑off' signal

Ter. 26     Ground, hot‑wire mass air flow meter P 44/Ter. 2

Ter. 27     Battery Ter. 1 5

Ter. 28     Signal, oxygen sensor P 32

Ter. 29     Unoccupied

Ter. 30     Ground supply for:

               ‑ knock sensor P 46

               ‑ coolant temperature sensor P 12

               ‑ intake air temperature sensor P 29

               ‑ throttle valve potentiometer P 34

Ter. 31     Ground actuation for hot start valve

Ter. 32     Tj signal for hoard computer

Ter. 33     Unoccupied

Ter. 34     Ground actuation for injection valve Y 7, cylinder 2

Ter. 35     Ground actuation for injection valve Y 7, cylinder 4

Ter. 36     Ground actuation for fuel pump relay K 68/Ter. 85

Ter. 37     Voltage supply for:

               ‑ control unit K 61

               ‑ hot‑wire mass air flow meter P 44/Ter. 5

Ter. 38     Unoccupied

Ter. 39     Unoccupied

Ter. 40     Input signal, air conditioning compressor

Ter. 41     Input switch, air conditioning ready

Ter. 42     Ground Ter. 31

Ter. 43     Tachometer

Ter. 44     Signal, Intake air temperature sensor P 29

Ter. 45     Signal, coolant temperature sensor P 12

Ter. 46     Unoccupied

Ter. 47     Unoccupied

Ter. 48     Signal, inductive pulse pick‑up P 35/Ter. 2

Ter. 49     Ground, inductive pulse pick‑up P 35/Ter. 1

Ter. 50     Unoccupied

Ter. 51     Unoccupied

Ter. 52     Recognition ‑ reverse gear

Ter. 53     Signal, throttle valve potentiometer P 34/Ter. 3

Ter. 54     Unoccupied

Ter. 55     Bi directional data lead, diagnostic plug X 13/Ter. 6

DIAGNOSIS

INTRODUCTION

The program section self‑diagnosis within the control unit, checks the sensor signals against pre‑programmed, 'look‑up' tables. If an open circuit should occur say, in the temperature sensor, this would result in an infinite resistance. The corresponding temperature of ‑35 °C is not plausible. The malfunction is therefore recognised.

Similar plausibility controls are carried out with other sensor signals.

A fault which has been recognised is stored with the corresponding trouble code.

BACK‑UP OPERATION

If a fault does occur, the control unit substitutes the following values so that the vehicle is not immobilised.

IMPORTANT NOTES AND PRECAUTIONS

When dealing with electronic control units and systems, observe the following instructions carefully, to avoid damaging the engine, control unit or ignition coil or endangering life:

1.     'Trouble codes' in the memory of electronic systems with self‑diagnosis are deleted by disconnecting the battery.

2.     Never start engine when battery connections are not absolutely tight.

3.     Wrong polarity of power supply (e.g. by battery terminals or ignition coil being wrongly connected) can lead to control unit being irreparably damaged.

4.     Disconnect battery from vehicle electrical system before charging or using a battery booster. Assist start only with a second 12 volt battery and jump cables.

5.     Never disconnect battery while engine is operating.

6.     Never short‑circuit ignition coil Ter. 1 to ground (e.g. to stop engine). Ignition coil and possibly also control unit could be irreparably damaged.

7.     Never allow battery positive terminal and ignition coil Ter. 1 to come into contact. Control unit will be damaged.

8.     Do not disconnect or connect wiring harness plug of control unit while ignition is switched on. First remove control relay or wart for approx. 20 seconds after switching off the ignition.

9.     Remove control unit at temperatures over 80 °C (drying oven).

10.  Remove control unit during electrical welding operations.

TROUBLE CODE TABLE

Safety Measures:

§                  Allow at least 20 seconds after switching off ignition before disconnecting/reconnecting plugs of electric/electronic modules.

§                  Never disconnect battery from vehicle electrical system with engine running.

§                  During welding work, always remove control units.

§                  At temperatures above +80 °C/+176 °F (drying oven), control units must be removed.

§                  Never use the quick‑charger for starting.

§                  Caution when touching voltage‑bearing parts of the ignition system.

§                  Use only high‑resistance voltage tester for checking.

IMPORTANT:   After disconnecting the battery, volatile memories must be reprogrammed. In the case of radio coding and radio station programming, the customer should be informed about the decoding and deleted station programming.

Diagram of Motronic M 2.7