GF32.33-D-2005H Electronic Level Control (ELC) at Vehicle Standstill Function
GF32.33-D-2005H Electronic Level Control (ELC) At Vehicle Standstill Function
- with CODE (CE2) Rear air suspension
The "electronic level control (ELC [ENR]) at vehicle standstill function" is made up of the following subfunctions:
^ Self-test
^ Behavior during starting procedure
^ Behavior at "circuit 30 OFF" status
^ Behavior at "circuit 15 OFF" status (sleep mode)
^ Behavior at "circuit 15 ON" status
^ Manual deactivation of electronic level control system
^ Automatic deactivation of electronic level control system
Self-test
At a "circuit 15 ON" status, the ELC control unit (N97) (on model 639 (N51/3)) performs a self-test and a system test.
Depending on the fault, it is stored either in a temporary or permanent memory.
Depending on the fault, the ELC [ENR] warning lamp (A1e5) in the instrument cluster (A1) is activated and the ELC Behavior during starting procedure system is switched to passive/service mode.
The mode is indicated by the ELC warning lamp in the instrument cluster and the indicator lamp in the lock electronic level control switch (S77/1) lighting permanently.
Behavior during starting procedure
If during the raising process, circuit 15X (start engine) is activated, then the raising process is immediately interrupted. The raising process is continued with once the engine is recognized to be in a stable condition.
Behavior at "circuit 30 OFF" status
If the battery (G1) is disconnected, the temporary faults (malfunctions) are deleted, the hard faults remain stored. After disconnecting the battery a self-test is performed.
Behavior at "circuit 15 OFF" status (sleep mode)
Function requirements
^ Circuit 15 OFF
^ Last control operation of ELC system completed
Model 639
The ELC control unit (and therefore the Controller Area Network bus class B (interior) (CAN-B)) at "circuit 15 OFF" status and with an open liftgate is only active for t = 50 s.
The background to this is that the raise or lower level control switch (S77) is not wake-up capable, i.e. the raise or lower level control switch cannot activate the electronic level control system when it is in the sleep mode.
During this period automatic adaptations to the vehicle's rear axle level can be made by the ELC control unit.
If the liftgate is closed, the electronic level control system and the CAN-B switch to the quiescent state as quickly as possible.
The quiescent state of CAN-B is interrupted through renewed activation of circuit 15.
Model 906
The raise/lower electronic level control switch (S77/2) is not connected to a wake-up capable input of the ELC control unit. Therefore the electronic level control system and the CAN-B always enters the sleep mode as soon as possible after a "circuit 15 OFF" status, because it can be activated at any given time again.
Model 639 and model 906
Following "circuit 15 OFF" and when CAN B is in the quiescent state, the ELC control unit stores the last set 3 operating modes (automatic mode, manual ode or passive/service mode) and when CAN-B is activated again, it automatically switches to the stored operating mode.
Behavior at "circuit 15 ON" status
At a "circuit 15 ON" status the lock electronic level control switch and the raise/lower electronic level control switch (for model 639 raise or lower level control switch) can be used to select between the following 3 operating modes:
- Automatic mode (automatic level adaptation):
- In this mode, the rear axle level is adjusted automatically while the vehicle is in motion or stationary. In this mode, the ELC [ENR] warning lamp in the instrument cluster and the indicator lamp in the lock electronic level control switch are not activated.
- Manual mode (manual raise and lower):
- In this mode, when the raise/lower electronic level control switch is activated (with model 639 raise or lower level control switch) the vehicle's rear axle level is manually raised or lowered in each case by up to approx. 60 mm.
The mode is indicated by the electronic level control warning lamp in the instrument cluster flashing on and off.
The mode is also indicated on model 639 by the indicator lamp in the lock level control switch (S77/1) flashing on and off.
- Passive/service mode (e.g. workshop):
- In this mode, no level control takes place at the rear axle, e.g. when performing work on the vehicle at the workshop or if the ELC system has malfunctioned. The mode is indicated by the ELC warning lamp in the instrument cluster and the indicator lamp in the lock electronic level control switch lighting permanently.
To ensure that it is possible to switch between the 3 operating modes (automatic mode, manual mode or passive/service mode), the lock electronic level control switch or the raise/lower electronic level control switch (for model 639 raise or lower level control switch) has to be pressed for t = 1.5 s.
Manual deactivation of electronic level control system
An automatic level adaptation of the electronic level control system can be deactivated by actuating the lock electronic level control switch, this may be necessary, e.g. when changing a wheel or when performing repair work on the vehicle lift.
Finally, the lock electronic level control switch can be used to activate the electronic level control (ELC [ENR]) system and therefore the automatic level adaptation again.
Automatic deactivation of electronic level control system
Automatic deactivation of the electronic level control system takes place under the following conditions:
- When a fault was detected
- "Circuit 61 OFF" and weak battery
- In order to protect the level control compressor (A9/1) against overheating as a result of repeated raising or lowering of the vehicle rear axle
- When the vehicle rear axle is raised or lowered on one or both sides quickly enough
- When the vehicle stops for t = 80 s on a vehicle lift (lowering time-out period)
- When CAN-B is in the quiescent state (sleep mode)
