12 51 001 Replacing wiring harness section for engine (M54)

WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2005 BMW 325xi, 2005 BMW 325i, 2005 BMW 325Ci, 2004 BMW 325xi, and 2004 BMW 325i. However, it is still accessible from the selected car via links, so may be relevant.

Interrogate fault memory of DME control unit.

Switch off ignition.

Follow instructions for disconnecting and connecting battery, refer to 12 00... INSTRUCTIONS FOR DISCONNECTING AND CONNECTING BATTERY .

Disconnect battery negative lead from battery.

WARNING: Scalding hazard! Only perform these tasks on an engine that has cooled down.

E53 And E46:

Remove underbody protection.

E53, E46, E39:

Detach plug (1) from oil level sensor.

Unclip cable from cable holder (2) and lay upwards.

Fig 1: Detaching Plug From Oil Level Sensor

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When fitted:

Remove vacuum tank for exhaust flap.

Unlock plug (1) and detach from pulse generator for crankshaft.

Fig 2: Unlocking Plug And Detach From Pulse Generator

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Release nuts (1).

Tightening torque, refer to 12 41 4AZ in ENGINE ELECTRICAL SYSTEM - TIGHTENING TORQUES - 325I, CI & XI - E46 .

Detach leads (2) from starter motor.

Fig 3: Detaching Leads From Starter Motor

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Unlock plug (1) and detach from coolant temperature sensor.

Release cable tie (2).

Fig 4: Unlocking Plug And Detach From Coolant Temperature Sensor

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Disconnect plug connection (1).

Fig 5: Disconnecting Plug Connection

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E53 Only:

Release cable tie (2) on transmission housing and disconnect cable (3).

Unlock plug (1) and detach from reverse gear switch.

Fig 6: Unlocking Plug And Detach From Reverse Gear Switch

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E53 And E46 Only:

Remove heater bulkhead, refer to 51 71 080 REMOVING AND INSTALLING/REPLACING HEATER BULKHEAD .

E53, E46 And E39:

Unclip plug connections (1) on oxygen control sensors from holders and disconnect.

Fig 7: Uncliping Plug Connections On Oxygen Control Sensors

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E53 Only:

Disconnect all plugs in control unit box.

Unlock cable holders (2).

Remove cables (1) from cable holders (2).

Release screws (3).

Remove holder (4).

Fig 8: Removing Cables From Cable Holders

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Release nut.

Remove grounding cables from ground support point.

Detach profile seal (1) towards top.

Fig 9: Detaching Profile Seal Towards Top

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Installation:

To prevent leaks, you must install profile seals correctly.

Detach profile seals (1) towards top.

Fig 10: Detaching Profile Seals Towards Top

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Installation:

To prevent leaks, you must install profile seals correctly.

E46 Only:

Pull off sealing strip (1).

Fig 11: Pulling Off Sealing Strip

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Withdraw vacuum line and battery positive lead from assembly compartment partition wall.

Turn fasteners (1) through 90°. This unlocks the fasteners (1).

Remove assembly compartment partition wall (2) towards top.

Fig 12: Removing Assembly Compartment Partition

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Installation:

To ensure watertightness, it is essential to install profile seals of vacuum line, battery positive lead and engine wiring harness correctly.

Fig 13: Installing Profile Seals Of Vacuum Line

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Release screws (1).

Installation:

Remove cover from electronics box.

Pull out profile seal (1).

Unlock plug (2) and disconnect.

Fig 14: Pulling Out Profile Seal

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E39 Only:

Disconnect all plugs in control unit box.

Remove air duct on left and right.

Release fasteners (1).

Detach rubber strip (2).

Fig 15: Detaching Rubber Strip (2)

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Release fasteners (1).

Remove firewall panel (2).

Fig 16: Releasing Fasteners

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E53, E46 And E39:

Remove throttle assembly.

Remove intake air manifold.

Unlock plug (1) and detach from alternator.

Fig 17: Unlocking Plug (1) And Detaching From Alternator

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Unlock plug (1) on pulse generator of inlet camshaft and detach from cable duct (2).

Fig 18: Unlocking Plug (1) On Pulse Generator Of Inlet Camshaft And Detaching From Cable Duct (2)

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Unlock plug (1) and detach from solenoid valve of VANOS adjustment unit.

Unlock plug (2) and detach from pulse generator for exhaust camshaft.

Fig 19: Unlocking Plug And Detach From Solenoid Valve Of VANOS Adjustment Unit

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Unlock plug (1) and detach from thermostat housing.

Fig 20: Unlocking Plug And Detach From Thermostat Housing

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NOTE: Interrogate fault memory of DME control unit. Check stored fault messages. Rectify faults. Then clear fault memory.