Removal and installation the DME control unit (BMW 5 Series E39)

Note: Each control unit is programmed with certain basic parameters, which represent only average values. The control unit, depending on the engine condition, receives different values of input quantities from the sensors, which are compared with the accumulated values. The control unit then changes the execution commands accordingly. New values of quantities are accumulated, and thus the so-called "learning" process occurs.

If the DME control unit is without power supply for more than one hour (the unit is removed or the battery is disconnected), then its self-learning system loses the accumulated values of quantities.

When commissioning a control unit with erased value data or when installing a new unit, the system must accumulate the value data again. This process after starting the engine can lead to unstable engine operation at idle and malfunctions when operating in forced idle mode. It is necessary to drive the vehicle for several minutes at variable speed until all values characterizing the engine condition have leveled out.

After installing a new control unit at a BMW service station, it is necessary to enter the vehicle code and program it. This requires a device that allows diagnostics and data entry. If possible, the engine should be warmed up while driving the car with the old control unit, and then install the new control unit with the warm engine. This allows for faster adaptation of the new control unit to operating conditions.

Removal

Before removing the control unit, it is recommended that the BMW service station read and print out the information from the fault code memory. This will help determine what faults are present, see also.



Disconnect the negative (-) battery cable. The battery is located in the engine compartment behind the right side trim.

Caution: Read the instructions in the chapter "Removing and installing the battery".

To access the electronics unit, remove the microfilter box for cleaning the air in the cabin in the rear right part of the engine compartment.



Unscrew the mounting screws "1" and remove the fuse box cover.



Release the locking clamp of the plug connector and disconnect the connector.

Pull the control unit out of the retaining clips. There is no need to loosen the clamp mounting bolts.

Note: If the automatic transmission is equipped, the second control unit is located next to the DME control unit.

Installation

When purchasing a replacement unit, the unit number and coding are indicated. It is advisable to take the removed unit with you to identify the part.

Insert the control unit, connect the plug connector and secure it with the clamp.

Put the lid back in place.

Install the battery.

If the control unit has been de-energized for more than an hour or if a new unit has been installed: warm up the engine to operating temperature. Perform a test drive of approximately 10 minutes at various speeds. In this case, the control unit "learns" the engine parameters.