12 51 001 Replacing wiring harness section for engine (N55)
Aluminum screws/bolts are permitted with and without color coding (blue).
For reliable identification:
Jointing torque and angle of rotation must be observed without fail (risk of damage).
Necessary preliminary work:
- Read out the fault memory of the DME control unit.
- Switch off ignition.
- Disconnect BATTERY EARTH LEAD .
- Remove right suspension cross-brace. See 51 71 346 REMOVING AND INSTALLING/REPLACING RIGHT (REAR) SUSPENSION CROSS-BRACE .
- Remove sound insulation for bulkhead on right. See 51 71... REMOVING AND INSTALLING/REPLACING SOUND INSULATION FOR BULKHEAD UPPER PART .
- Remove sound insulation at the rear of the engine.
- Remove intake PLENUM .
- Partially detach WIRING HARNESS for injectors and ignition coils.
- Remove CLEAN AIR PIPE .
- Remove FAN COWL .
- Remove front UNDERBODY PROTECTION .
- Remove rear underbody protection. See 51 47 491 REMOVING REFITTING/REPLACING REAR ENGINE UNDERCOVER .
Disconnect connectors (1) and (2) and release from the carrier plate (3).
Disconnect all connectors from engine wiring harness on the carrier plate and release from the carrier plate (3).
Installation note:
Make sure rubber grommets are correctly fitted (water tightness).
Unclip grommet hold-down device (1).
Release wiring harnesses (2) from bulkhead.
Release screws (1).
Unclip upper part of cable channel (2) and expose the wiring harnesses.
Unlock all connectors (1) from control unit and disconnect.
Installation note:
Make sure grommets are correctly fitted (water tightness).
Release screws (1) below cable channel (2).
Replace aluminum screws.
Tightening torque 13 53 10AZ .
Release screws (1).
Tightening torque 12 90 8AZ .
Release cable channel (2).
Installation note:
Reconnect the earth connection.
Replace aluminum screws.
| Unlock and disconnect following connectors and lines | |
| Unlock connector on charging pressure sensor and disconnect | |
| Unlock connector on hot film air mass meter and disconnect | |
| Unlock connector on intake pressure sensor and disconnect | |
| Unlock connector on oxygen sensor and disconnect | |
| Unlock connector on monitoring sensor and disconnect | |
| Unlock connector on pressure converter and disconnect | |
| Unlock connector on high-pressure fuel sensor and disconnect | |
| Unlock connector on tank vent valve and disconnect | |
| Unlock connector on starter motor and disconnect | |
| Unlock connector on the knock sensors and disconnect | |
| Unlock connector on oil temperature sensor and disconnect | |
| Unlock connector on fuel low-pressure sensor and disconnect | |
| Unlock connector on throttle body and disconnect | |
| Unlock connector on high pressure pump and disconnect | |
| Unlock connector on alternator and disconnect | |
| Unlock connector on air conditioning compressor and disconnect | |
| Unlock connector on oil level sensor and disconnect | |
| Unlock connector on crankshaft sensor and disconnect | |
| Unlock connector on heating element for air duct and disconnect | |
| Unlock connector on coolant thermostat and disconnect | |
| Unlock connector on hydraulic valve and disconnect | |
| Unlock connector on the coolant pump and disconnect | |
| Unlock connector on exhaust turbocharger and disconnect | |
| Unlock connector on both camshaft adjustment solenoid valves and disconnect | |
| Release earth cable on crankcase lower section Tightening torque 12 90 9AZ . | |
| Release earth cable at rear of cylinder head Tightening torque, 12 90 10AZ . | |
| Unlock connector on intake camshaft pulse sensor and disconnect | |
| Unlock connector on exhaust camshaft pulse sensor and disconnect | |
| Unlock connector on oil pressure switch and disconnect | |
| Unlock connector on switching motor for eccentric shaft and disconnect |
Release wiring harness if necessary from existing clips and clamps.
Feed out wiring harness and remove.
Installation note:
Check wiring harness installation arrangement.
Check plug connections for correct fit.
Check stored fault message.
Clear diagnostic fault entries from fault memory.