Notes on replacement of automatic luggage compartment lid actuation control unit

After the emergency operation mode has been activated, when restarting the automatic luggage compartment lid actuation control unit (HKL) it is important to ensure that the plug connections to the electric motors (luggage compartment lid lifting drive, roller cover for luggage compartment drive) are connected first. Then connect the plug for the vehicle electrical system. The sequence is reversed for the removal procedure. That means: Start by disconnecting the plugs leading to the onboard electrical system.

Before replacing the automatic luggage compartment lid actuation's (HKL) control unit first note the stored opening height at the Central Information Display (CID) and transfer it to the new automatic luggage compartment lid actuation control unit.

Note for service technicians: 

After a luggage compartment lid lifting drive or a control unit for automatic luggage compartment lid actuation (HKL) has been replaced, the tailgate's opening and closing procedures must be adapted to the vehicle. Following installation the new automatic luggage compartment lid actuation control module or new luggage compartment lid lifting drives will not have any data on the position of the tailgate. The prescribed service function must be executed for initialization.

Following replacement of the control unit for the automatic luggage compartment lid actuation or luggage compartment lid lifting drive it is necessary to reprogram the upper mechanical end stop of the tailgate. To do so, the luggage compartment lid is moved to the upper end stop until it stops. This blocking of the tailgate and the subsequent suppression of the hall effect sensor impulses of the luggage compartment lid lifting drives marks the point of the maximum opening angle of the tailgate. A value of approx. 5 % of the total hall sensor impulses is subtracted from this point. This is the future opening angle of the tailgate. This point is also called the "soft stop".

The Soft Stop feature prevents the tailgate from opening all the way to its upper mechanical end stop. Should the tailgate open all the way to the end stop (travel stop) damage to the luggage compartment lid lifting drive and/or noises could result.

The position of the lower travel stop is defined based on the change in the status of the rear lid contact switch from open to closed.

The following graphic illustration shows the automatic luggage compartment lid actuation control unit for the roller cover for the luggage compartment electric motor and for the luggage compartment lid lifting drives.

Fig 1: Identifying Plug Connections

Courtesy of BMW OF NORTH AMERICA, INC.

The following illustration shows the automatic luggage compartment lid actuation control unit for the roller cover for luggage compartment electric motor.

Fig 2: Identifying Plug Connections

Courtesy of BMW OF NORTH AMERICA, INC.