12 63 520 Replacing main relay (M62, M54)

Switch off ignition.

Connect DIS Tester.

Detach sealing strips (1).

Fig 1: Detach Sealing Strips

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Turn bar through approx. 90°.

Remove cover.

Fig 2: Removing Cover

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Release lock (1).

Remove air funnel (2) towards top.

Fig 3: Removing Air Funnel Towards Top

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Release screws.

Tightening torque, see 12 90 4AZ in ENGINE ELECTRICAL SYSTEM - TIGHTENING TORQUES .

Remove cover (1) on control unit box.

Fig 4: Removing Cover On Control Unit Box

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Installation: 

Insert fixtures (1) of cover for control unit box in openings (2).

Fig 5: Inserting Fixtures Of Cover For Control Unit Box In Openings

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Order:

1. Main relay of Digital Motor Electronics
2. Engine fuses of Digital Motor Electronics
   Fig 6: Identifying Main Relay Of Digital Motor Electronics

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Notes on troubleshooting: 

If the starter motor cranks the engine during the starting sequence but the engine fails to fire, then:

1. Check engine fuses
2. If fuses are blown, replace them completely with fuse holder
3. Find out why fuses have blown

   Continue troubleshooting as per DIS instructions.