GF54.10-P-1050FL Engine Off Energy Management, Function

GF54.10-P-1050FL Engine Off Energy Management, Function

Function requirements, general
^ Circuit 61 OFF (vehicle parked)

The CDI control unit (N3/9) (with diesel engine) or ME-SFI control unit (N3/10) (with gasoline engine) makes available the circuit status of circuit 61 via the chassis CAN (CAN E). The front SAM control unit with fuse and relay module (N10/1) forwards this via the interior CAN (CAN B) to the rear SAM control unit with fuse and relay module (N10/2).

Engine off energy management, general
Engine off energy management ensures the stability of the onboard electrical system and the starting capability of the vehicle when the engine is off.
This functionality is integrated into the rear SAM control unit and serves to extend the service life of the on-board electrical system battery (G1). To this end, active electrical consumers may be switched off.

Engine off energy management comprises the following subfunctions:
^ Consumer shutoff function sequence
^ No-load current management function sequence
^ Function sequence of remote charging/jump start

Additional function requirements for consumer shutoff
^ Circuit 15 ON or Circuit 15R ON
^ On-board electrical system emergency mode not active

The electronic ignition lock control unit (N73) transmits the circuit status of circuit 15 via the interior CAN to the rear SAM control unit.

Consumer shutoff function sequence
When the on-board electrical system voltage falls below U = 11.8 V, the consumer shutoff function will be activated under the following conditions:
- Engine OFF (circuit 61 OFF)
- Change from circuit 15 ON to circuit 15R ON

Given constant shutoff conditions, one consumer will be shut off every t = 5 s in addition to the consumer reduction from the engine on energy management function. The shutoff sequence is shown in the following table.

The list includes those consumers whose power supply is reduced or cutoff as part of the engine on energy management function (up to shutoff step 20).

Steps 1-24:

Even when the on-board electrical system voltage is stabilized at a value above
U = 11.8 V, consumer shutoff is not revoked. Power is only returned to the shutoff consumers following a reset, which is performed by turning the transmitter key (A8/1) to circuit 15C.

Additional function requirements for no-load current management
^ Transition from circuit 15R to circuit 15C

The electronic ignition lock control unit sends the circuit 15 status via the interior CAN to the rear SAM control unit.

No-load current management function sequence
No-load current management ensures the starting capability of the vehicle. The no-load current management is integrated in the rear SAM control unit and makes possible longer idle times of the vehicle.

To this end, power may be cut off to the consumers on circuit 30g through actuation of the no-load current shutoff relay (F32k2). The no-load current management tolerates an increased energy consumption for a certain time after switching off the engine (maximum t = 75 min). This allows, for example, the radio to be played while the car is being washed.

For this purpose the no-load current management checks in cycles the voltage and current consumption every t = 6 min. If in the process a high no-load current is established for a certain time, the no-load current switch is opened at the earliest after t = 75 min, but at the latest after 6 h.

Following a period of t = 6 h, or as soon as the on-board electrical system's voltage values drop below certain limits and compromise the starting capability of the vehicle, the extended run-on monitoring function initiates the following actions:
- Activate no-load current shutoff via Controller Area Network (data bus/CAN Bus) (CAN)
- Open no-load current shutoff relay

Before the no-load current switch is opened a corresponding signal to reduce the power of the control units is transmitted via CAN. This causes, for example, the overhead control panel control unit to move an open tilting/sliding roof into the tilt position No-load current management comprises the following subfunctions:
^ No-load current shutoff function sequence
^ No-load current diagnosis function sequence
^ No-load current reference value/residual charging current assessment function sequence

No-load current shutoff function sequence
The no-load current shutoff function comprises the following subfunctions:
^ Request consumer shutoff function sequence
^ Shut off consumers function sequence
^ Energize consumers function sequence

Request consumer shutoff function sequence
During the transition from circuit 15R to circuit 15C, the vehicle changes to the "vehicle rest" operating state. The timer counting down to no-load current shutoff is then started (waiting time t = 6 h). The no-load current is continuously monitored by the battery sensor (B95). At too high no-load current the no-load current shutoff relay is opened after t = 75 min at the earliest.
The data from the battery sensor are read and evaluated by the rear SAM control unit via the on-board electrical system LIN (LIN B7).
If during the waiting time the on-board electrical system voltage falls to U < 11.8 V, the no-load current shutoff relay will be opened early.

If U < 11.8 V, the battery sensor will go into sleep mode (reduced power consumption).

At t = 5 min. prior to the no-load current shutoff relay opening, the rear SAM control unit sends a shutoff signal via the interior CAN as advance notice to the control units involved. This shutoff signal is relevant to all control units receiving power via circuit 30g.
Via the interior CAN the shutoff signal is transmitted to:
- Instrument cluster (A1)
- Radio (A2) (with code (510) Audio 20 with CD changer or code (523) MB Audio 20 radio)
- Radio with auto pilot system (A2/56) (with code (511) Audio 50 APS incl. DVD changer or code (525) MB Audio 50 APS radio)
- COMAND controller unit (A40/3) (with code (512) COMAND APS incl. DVD changer or code (527) COMAND APS with single DVD drive (with navigation) or code (528) COMAND incl. DVD changer)
- Panoramic sliding roof control module (A98) (with code (413) Panoramic glass sunroof with top sliding sunroof)
- Pneumatic pump for dynamic multicontour seat (M40/1) (with code (432) Left and right dynamic multicontour seat)
- Front SAM control unit with fuse and relay module (/)N10/1
- Automatic air conditioning control and operating unit (N22/7)
- Rear seat heater control unit (N25/6) (with code (872) Electrically heated left and right rear seats)
- Steering wheel heater control unit (N25/7) (with code (443) Steering wheel heater
- Special vehicle multifunction control unit (N26/9) (with code (965) Electrical preinstallation for rental vehicle)
- Trailer recognition control unit (N28/1) (with code (550) Trailer hitch)
- Driver seat control unit (N32/1) (with code (275) Memory package for electrically adjustable front seats)
- Front passenger seat control unit (N32/2) (with code (275) Memory package for electrically adjustable front seats)
- Left front dynamic multicontour seat control unit (N32/19) (with code (432) Left and right dynamic multicontour seat)
- Right front dynamic multicontour seat control unit (N32/22) (with code (432) Left and right dynamic multicontour seat)
- Reversing camera control unit (N66/2) (with code (218) Reversing camera and code (498) Japan version)
- Left front door control unit (/)N69/1
- Right front door control unit (/)N69/2
- Left rear door control unit (/)N69/3
- Right rear door control unit (/)N69/4
- Keyless-Go control unit (N69/5) (with code (889) Keyless-Go)
- Overhead control panel control unit (with code (414) Power glass tilting/sliding sunroof)
- Electronic ignition lock control unit (N73)
- WSS (Weight Sensing System) control unit (N110) (with code (494) USA version)
- Trunk lid control unit (N121) (model 212.0 with code (881) Remote trunk closing (RTC [HDFS]))
- Liftgate control unit (N121/1) (model 212.2)

The front SAM control unit routes this signal via the chassis-CAN to the following control units:
- Left front reversible emergency tensioning retractor (A76)
- Right front reversible emergency tensioning retractor (A76/1)
- Supplemental restraint system control unit (/)N2/10
- CDI control unit (with diesel engine)
- ME-SFI [ME] control unit (with gasoline engine)
- PARKTRONIC control unit (N62) (with code (220) PARKTRONIC or code (230) Exclusive parking assist)
- Steering column module control unit (N80)
- Tire pressure monitor control unit (N88) (with code (475) Tire pressure monitor (premium))

If the interior CAN and chassis CAN are in "sleep mode" during signal transmission, the control units will be woken up. The involved control units will then prepare themselves for power supply shutoff.
Within t = 5 min., these control units will go into "power-down mode" (decentralized power management).

Shut off consumers function sequence
Following a period of t = 5 min., no-load current management opens the no-load current shutoff relay provided no closing causing event has occurred in the meantime. The rear SAM control unit sends the status of the no-load current shutoff relay via the interior CAN. The front SAM control unit receives this and provides it via the chassis CAN to the other control units.

Energize consumers function sequence
When the system wakes up, no-load current management closes the no-load current shutoff relay and all functions are made available again.

The no-load current shutoff relay will open again following a waiting time of t = 6 h or if the on-board electrical system voltage falls to U < 11.8 V or if the no-load current is too high.
If the rear SAM control unit receives a wake-up signal, no-load current management closes the no-load current shutoff relay and signals, via the interior CAN, that the wake-up conditions for the control units are again active. The front SAM control unit receives this signal and provides it via the chassis CAN to the other control units.
Closing the no-load current shutoff relay causes power to again be supplied via circuit 30g.

The following conditions will trigger the closure of the no-load current shutoff relay:
- Circuit 15R switches on:
The waiting time timer is reset. The no-load current shutoff relay remains closed as long as the status of circuit 15R is ON.
- A door is unlocked or opened or circuit 15C is switched on:
The waiting time timer is reset.
- The hazard warning system, the standing or parking lights, or the signaling system on special-purpose vehicles is switched on:
The waiting time timer is reset.
- The anti-theft alarm system (ATA [EDW]) is activated (with code (551) Antitheft alarm system (ATA [EDW])):
The waiting time timer will be reset.
- The panic alarm is triggered (with code (763) Radio remote control with panic switch):
The waiting time timer will be reset.
- Activation of stationary heater (with code (228) stationary heater):
The timer of the waiting time will be reset.

No-load current diagnosis function sequence
No-load current diagnosis records data to help troubleshoot possible fault profiles.

The no-load current diagnosis function comprises the following subfunctions:
^ Activate no-load current diagnosis function sequence
^ Cancel/end no-load current diagnosis function sequence

Additional function requirements for Activate no-load current diagnosis
^ Terminal 15R OFF

Activate no-load current diagnosis function sequence
Any of the following wake-up events will cause the battery sensor to start no-load current diagnosis via the on-board electrical system LIN:
- Increased no-load current following expiration of tolerance time of t = 75 min.
- On-board electrical system voltage values fall below limits and there has been a change in the kilometer reading since the last fault roll entry caused by undervoltage (also before expiration of tolerance time of t = 75 min.)

With the first waking event an entry in the no-load current fault roll takes place. The no-load current value is then monitored cyclically from that time on. The values will be updated if there are significant changes or if the no-load current diagnosis is canceled.

The following data are stored in nonvolatile memory in the no-load current fault roll:
- No-load current value upon occurrence of wake-up event
- Maximum no-load current during no-load current fault phase
- Minimum no-load current during no-load current fault phase
- Voltage of on-board electrical system battery upon occurrence of wake-up event
- Voltage of on-board electrical system battery at end of no-load current fault phase
- Duration of no-load current fault phase (in minutes)
- Kilometer reading
- Consumer status

As long as no-load current diagnosis is active, each additional battery sensor wake-up event will cause the data record to be updated.

Additional function requirements for Cancel/end no-load current diagnosis
^ terminal 15R
^ On-board electrical system voltage values fall below limits

Cancel/end no-load current diagnosis function sequence
The no-load current-diagnosis is terminated if the limits (U < 11,8 V) for on-board electrical system voltage are dropped below. The battery sensor will discontinue no-load current monitoring in order to minimize electricity consumption. Once this happens, no further entries will be added to the fault roll.

Additional function requirements for no-load current reference value/residual charging current assessment
^ Terminal 30

No-load current reference value/residual charging current assessment function sequence
After the vehicle has gone through production testing and possible runs on the test track, the no-load current has to be measured and an assessment made of the residual charging current of the on-board electrical system battery.

The no-load current-reference value/residual load current evaluation is comprised of the following subfunctions:
^ No-load current reference value measurement function sequence
^ Residual charging current assessment function sequence

No-load current reference value measurement function sequence
The measurement of the no-load current reference value is started using the diagnostic-tester at circuit 15R or higher.

The message "Measure no-load current" appears in the multifunction display (A1p13) of the instrument cluster. The diagnostic tester must then be removed and the vehicle locked so that the vehicle's no-load current will quickly drop. The battery sensor will then sense and save the maximum no-load current level to occur following the locking of the vehicle.
After the vehicle is woken up, the battery sensor sends the measured no-load current value via the on-board electrical system LIN to the rear SAM control unit, which then saves it as the no-load current reference value in nonvolatile memory.
The no-load current reference value can be read out using the diagnostic tester.

If the measured no-load current is within a defined tolerance range, the message in the multifunction display will disappear.

If the no-load current reference value is too high, a fault message will be shown in the multifunction display of the instrument cluster and measurement will begin again.

Residual charging current assessment function sequence
During production, charge is removed from the battery in the course of various function tests. The charge level of the on-board electrical system battery must therefore be assessed at the end of assembly. The charge level (ratio of current charge to the maximum storable charge in the on-board electrical system battery) serves as the measure for a sufficiently charged on-board electrical system battery.
This value must be above 80%.
If the charge level is below 80%, a fault message will be shown in the multifunction display of the instrument cluster. Measurement of the residual charging current is only done following successful measurement of the no-load current reference value. As a rule, the two values are released together.

Function sequence of remote charging/jump start
If the on-board electrical system battery does not have enough capacity to start the engine, the on-board electrical system battery must be charged or a jump start carried out.

As of 1.6.10 during the jump start process or in the workshop for test work one of the front doors must be opened so that the generator management changes into jump start mode and the generator voltage is increased to U = 13.,9 V.