Starting and Charging: Service and Repair
Wiring Harness - Replacing Engine Section (M73)
Follow instructions on connecting and disconnecting battery.
Switch off ignition.
Remove battery negative line.
Remove complete splash guard.
Remove fan wheel.
Rotate screws through 90°. Remove cover from cylinder head cover.
Press down detent (2) and remove plug connection (1).
Open clips (1).
Unfasten hose clip (2) from auxiliary hose for air pump.
Disconnect plug-in connection (3).
Unfasten hose clip (4).
Remove upper section of right suction filter housing with mass air flow sensor.
Open clips (1).
Unfasten hose clip (2) from auxiliary hose for air pump.
Disconnect plug-in connection (3).
Remove upper section of left suction filter housing with mass air flow sensor.
Unfasten screws in retaining brackets (1 and 2) on cylinder head cover. Remove retaining brackets.
Unfasten connections on left ignition coils (1 and 2).
Disconnect plug connection on tank vent valve.
Unfasten screw connection on positive battery line from positive battery terminal.
Disconnect plug connection (1) from camshaft sensor and plug connection (2) from vacuum control unit.
Disconnect left plug connections (1 and 2).
Remove tank vent valves (1 and 2) with bracket.
Disconnect connections on alternator, unfastening cable ties (1 and 2).
Connections here illustrated on removed alternator.
Unfasten plug connection (1).
Unfasten nut (2).
Unclip diagnosis connector from bracket.
Disconnect right plug connections (1 and 2).
Disconnect plug connections on actuator motors for throttle valves.
Disconnect plug connection on cable ducts (1 and 2).
(1) Knock sensor on cylinder (1 to 3)
(2) Knock sensor on cylinder (4 to 6)
Disconnect plug connection on cable ducts (1 and 2).
(1) Knock sensor on cylinder (7 to 9)
(2) Knock sensor on cylinder (10 to 12)
Unfasten nut on rear cable duct.
Unfasten nut.
Unfasten plug connection on injector valves.
Open fast release connections on tank vent valves, press down interlock (1) and remove hose (2).
Unclip oil drip tray.
Remove fan.
Pressure hose from pressure pipe on non-return valve for air induction to cylinders 7 - 12.
Loosen hose clamp. Pull off hose.
Pressure hose from pressure pipe on non-return valve for air induction to cylinders 1 - 6.
Loosen hose clamp. Pull off hose.
Unfasten hose clip to remove pressure hose from air pump to pressure pipe. Pull off hose.
Unscrew and remove pressure pipe with bracket (1). Remove non- return valve for cylinders 1-6.
Unfasten plug connection from temperature sensor for coolant temperature.
Unfasten plug connection (1) from oil level sensor and starter motor (2).
Slide cable duct backwards to remove from front interlock (1) then lift it up (2).
At this point, the wiring harness is effectively removed, e.g. it was possible to remove the intake air manifold.
Unfasten plug connection on impulse sensor on crankshaft (flywheel) for DME of cylinder 1 - 6 (DME 1).
Installation:
Clip line from impulse sensor (2) into bracket (1).
Unfasten plug connection on impulse sensor on crankshaft (flywheel) for DME of cylinder 7 - 12 (DME 2).
Unclip lines from bracket on transmission bell housing.
Installation:
Clip lines into bracket on the transmission bell housing.
Installation:
Clip lines into bracket on the transmission bell housing.
Installation:
Clip lines into bracket on the transmission bell housing.
Unfasten plug connection for position switch on automatic transmission.
Unfasten plug connection for shift unit on automatic transmission.
Unfasten screws and remove cover of plug connections for left and right Lambda oxygen sensors. Mark (identify) plug connections and disconnect.
Unclip wiring harnesses from left and right Lambda oxygen sensors on the heat shields.
Unclip and remove wiring harness on transmission bracket.
Unclip and remove wiring harness on transmission bracket.
Remove heat baffle plates from left and right catalytic converters.
Extract complete wiring harness from vehicle underside.
Remove from top side of vehicle:
Disconnect cable tie on cylinder head of cylinder bank 1-6
Ground wires on cap of spring strut shock absorber: unfasten nuts.
Unfasten screws in cover on electronics box.
Remove relays (1 to 3) with bracket.
1. Relays for Digital Motor Electronics (DME 1)
2. Relays for Digital Motor Electronics (DME 2) (can be recognized because cross section of feed lines is greater than 2.5 mm(2))
3. Relay for starter motor inhibit
Disconnect plug connection on temperature sensor for electronics box.
Disconnect plug connections (1 to 4).
1. Control unit for Digital Motor Electronics for cylinders 1 - 6 (DME 1)
2. Control unit for Digital Motor Electronics for cylinders 7 - 12 (DME 2)
3. Control unit for Electronic Transmission Control (EGS)
4. Control unit for Electronic Engine Power Control (EML)
Disconnect plug connections (1 to 4). Unfasten cable tie on back of cylinder head (cylinder bank 7-12).
Remove complete wiring harness.