Engine Control Module: Service and Repair

12 14 550 - Replacing control unit (DME) (N54)





Important!
Read and comply with notes on protection against electrostatic damage (ESD protection)





Necessary preliminary tasks:
- Switch off ignition
- Disconnect battery negative lead 61 20 900 Disconnecting and Connecting Battery Negative Lead
- Remove microfilter housing 64 31 081 Removing and Installing/Replacing Microfilter Housing

Important!
Follow instructions Service and Repair for removing and installing control units





Replacement:
- Carry out programming/coding
- If no data can be read out from the previous control unit, carry out injection quantity adjustment (description at end of instruction).





Important!
It is absolutely essential to read out the fault memory with the BMW diagnosis system and to create a fault memory printout.

Switch off ignition.





Lever out expander rivet.
Remove gasket (1).
Release screws (2).
Feed out partition (3) and remove.





Lever out expander rivet.
Release locks in direction of arrow.
Feed out fresh-air duct (1) and remove.





Open retainers.
Release lock (1) in direction of arrow.
Remove cover (2).





Release screws and remove retaining bar (1).
Unlock upper section (2) of partition seal in direction of arrow and remove.
Release grommets (3) for wiring harnesses from lower section of partition seal and from electronics box.

Installation Note:
Make sure grommets are correctly seated (watertightness).





Unlock plugs (1) using slide in direction of arrow and remove.
Remove control unit (2).

Installation Note:
Replacement:
Note device identification number and coding.





Injector adjustment:
If the DME control unit has been replaced, it will also be necessary to carry out adjustment of the injectors!
Injector adjustment is carried out with the aid of so-called adjustment values.
The adjustment values are printed in two blocks of three digits on each injector.
The adjustment values must be stored in the new control unit!





If injector adjustment is not carried out, the engine may run roughly or fail to start.
Read off the adjustment values and enter according to the installation location (cylinder) of the injectors:
- Connect DIS Tester
- Identify car
- Select "Function selection"
- Select "Service functions"
- Select "Engine electronics"
- Select "Adjustment programs"
- Select "Adjust injectors"
- Change "Test schedule"
- The adjustment value must be entered for each cylinder.





Note:
Check stored fault message.
Now clear the fault memory.