12 14 518 Replacing impulse sensor (cylinder bank 7-12) (M73)

Interrogate fault memory of DME control unit.

Switch off ignition.

Remove rear splash guard.

Disconnect plug connection on impulse sensor on crankshaft (flywheel) for DME 2 (cylinder 7 -12).

Fig 1: Disconnecting DME 2 Impulse Sensor Crankshaft Plug Connection (Cylinder 7-12)

Unscrew screw. Remove impulse sensor.

Installation:

Observe the following when replacing the transmission, the flywheel or the pulse sensor:

Note whether one or more shims are installed between the transmission housing and the pulse sensor. If one or more shims are installed, the distance between the pulse sensor and the pulse teeth of the increment wheel must be measured.

Fig 2: Removing Impulse Sensor (Cylinder 7-12)

Turn the engine on the front central bolt so that a full pulse tooth (1) can be seen through the opening of the removed pulse sensor. Make sure that the pulse tooth (1) is exactly centered in the hole.

Fig 3: Locating Pulse Tooth (Cylinder 7-12)

The depth to the pulse teeth of the flywheel must be determined with special tool 00 2 407.

Note depth.

Fig 4: Measuring Flywheel Pulse Teeth Depth (Cylinder 7-12)

Measure depth (A) of pulse sensor.

Deduct depth (A) of pulse sensor from depth of flywheel. This result is the gap dimension.

Adjust a gap dimension of 0.55 +/- 0.2 mm with the shims.

The dimension 0.55 mm should be achieved as exactly as possible in order to:

Enable exact misfiring recognition.
Prevent pulse sensor from contacting pulse teeth.

Fig 5: Measuring Pulse Sensor Depth (Cylinder 7-12)

Installation:

Interrogate fault memory of control unit on Digital Motor Electronics (DME), check fault messages in memory, rectify faults and cancel fault memory.