Engine Off Energy Management, Function - GF54.10-P-1050CE
MODEL 204.0/2 as of model year 2009/YoM 08
MODEL 204.3
MODEL 204.9
Function requirements, general
- "Engine running" or "drivetrain operational" signal not set (vehicle switched off)
The CDI control unit (N3/9) (with diesel engine) or the ME-SFI [ME] control unit (N3/10) (with gasoline engine) sends the "Engine running" or the "Drivetrain operational" signal over the chassis CAN (CAN E), front SAM control unit with fuse and relay module (N10/1) and 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 on-board 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 encompasses the following subfunctions:
- Function sequence for consumer shutoff
- Function sequence for no-load current management
- Function sequence for remote charging/jump start
Additional function requirements for consumer shutoff
D Circuit 15 ON or circuit 15R ON
D 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.
Function sequence for consumer shutoff
The rear SAM control unit actuates the consumer shutoff function under the following conditions:
- On-board electrical system voltage lowered to less than U = 11.8 V
- Engine 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 as of 1.6.12 in the table below.
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 15).
| Shutoff step | Switch off stage | Consumers with reduced or no power | Executing control unit | Maximum Current in A |
|---|---|---|---|---|
| 1 | 1 | Heater stage 6 PTC heater booster (R22/3) (with engine 642.8/9, 646.8, 651.9) passenger side | Automatic air conditioning control and operating unit (N22/7) | 18.5 |
| 2 | 2 | Heater stage 5 PTC heater booster (R22/3) (with engine 642.8/9, 646.8, 651.9) driver side | Automatic air conditioning control and operating unit (N22/7) | 18.5 |
| 3 | 3 | Heater stage 4 PTC heater booster (R22/3) (with engine 642.8/9, 646.8, 651.9) passenger side | Automatic air conditioning control and operating unit (N22/7) | 18.5 |
| 4 | 4 | Heater stage 3 PTC heater booster (R22/3) (with engine 642.8/9, 646.8, 651.9) driver side | Automatic air conditioning control and operating unit (N22/7) | 18.5 |
| 5 | 5 | Heater stage 2 PTC heater booster (R22/3) (with engine 642.8/9, 646.8, 651.9) passenger side | Automatic air conditioning control and operating unit (N22/7) | 18.5 |
| 6 | 6 | Heater stage 1 PTC heater booster (R22/3) (with engine 642.8/9, 646.8, 651.9) driver side | Automatic air conditioning control and operating unit (N22/7) | 18.5 |
| 7 | 7 | Seat heater level 3 (with code (873) Seat heater for left and right front seats) | Rear SAM control unit with fuse and relay module (N10/2) | 13.2 |
| 8 | 8 | Seat heater level 2 (with code (873) Seat heater for left and right front seats) | Rear SAM control unit with fuse and relay module (N10/2) | 13.2 |
| 9 | 10 | Mirror heater (M21/1r1) and mirror heater (M21/2r1) | Left front door control unit (N69/1) and Right front door control unit (N69/2) | 3.5 |
| 10 | 12 | Rear window heater (R1) | Rear SAM control unit with fuse and relay module (N10/2) | 30.0 |
| 11 | 13 | Rear blower motor (M2/1) (with code (581) C-AAC) P = 50 % |
Automatic air conditioning control and operating unit (N22/7) | 5.5 |
| 12 | 14 | Blower motor (A32m1) P = 50% |
Automatic air conditioning control and operating unit (N22/7) | 16.0 |
| 13 | 15 | Combustion engine fan motor and air conditioning with integrated control (M4/7) P = 50% |
Automatic air conditioning control and operating unit (N22/7) | 31.0 |
| 14 | 16 | Circuit 15R relay (1) (N10/2kB) | Rear SAM control unit with fuse and relay module (N10/2) | 6 |
| 15 | 18 | Seat heater stage 1 (with code (873) Seat heater for left and right front seats) | Rear SAM control unit with fuse and relay module (N10/2) | 3.3 |
| 16 | 19 | Residual heat utilization (with code (581) Comfort automatic air conditioning and without code (494) USA version) | Automatic air conditioning control and operating unit (N22/7) | 8 |
| Rear automatic air conditioning operating unit (N22/4) (with code (581) Comfort automatic air conditioning) | 6 | |||
| 17 | 20 | Stationary heater (with code (228) Stationary heater) | Stationary heater control unit (A6n1) | 10 |
| 18 | 21 | Radio (A2) (with code (523) MB Audio 20 radio or code (510) Audio 20 incl. CD changer) or Radio with auto pilot system (A2/56) (with code (525) MB Audio 50 APS radio or code (511) Audio 50 APS incl. DVD changer) or COMAND controller unit (A40/3) (with code (527) COMAND APS with single DVD drive (with navigation) or code (512) COMAND incl. DVD changer or code (528) COMAND incl. DVD changer) |
Radio (A2) or Radio with auto pilot system (A2/56) or COMAND controller unit (A40/3) |
2 |
The shutoff sequence is shown up to 31.5.12 in the table below.
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 17).
| Shutoff step | Switch off stage | Consumers with reduced or no power | Executing control unit | Maximum Current in A |
|---|---|---|---|---|
| 1 | 1 | Heater stage 6 PTC heater booster (R22/3) (with engine 642.8/9, 646.8, 651.9) passenger side | Automatic air conditioning control and operating unit (N22/7) | 18.5 |
| 2 | 2 | Heater stage 5 PTC heater booster (R22/3) (with engine 642.8/9, 646.8, 651.9) driver side | Automatic air conditioning control and operating unit (N22/7) | 18.5 |
| 3 | 3 | Heater stage 4 PTC heater booster (R22/3) (with engine 642.8/9, 646.8, 651.9) passenger side | Automatic air conditioning control and operating unit (N22/7) | 18.5 |
| 4 | 4 | Heater stage 3 PTC heater booster (R22/3) (with engine 642.8/9, 646.8, 651.9) driver side | Automatic air conditioning control and operating unit (N22/7) | 18.5 |
| 5 | 5 | Heater stage 2 PTC heater booster (R22/3) (with engine 642.8/9, 646.8, 651.9) passenger side | Automatic air conditioning control and operating unit (N22/7) | 18.5 |
| 6 | 6 | Heater stage 1 PTC heater booster (R22/3) (with engine 642.8/9, 646.8, 651.9) driver side | Automatic air conditioning control and operating unit (N22/7) | 18.5 |
| 7 | 7 | Rear blower motor (M2/1) (with code (581) C-AAC) P = 50 % |
Automatic air conditioning control and operating unit (N22/7) | 5.5 |
| 8 | 8 | Blower motor (A32m1) P = 50% |
Automatic air conditioning control and operating unit (N22/7) | 16.0 |
| 9 | 9 | Combustion engine fan motor and air conditioning with integrated control (M4/7) P = 50% |
Automatic air conditioning control and operating unit (N22/7) | 31.0 |
| 10 | 10 | Trailer socket (X58) (with code (550) Trailer hitch) | Trailer recognition control unit (N28/1) (with code (550) Trailer hitch) | 8 |
| 11 | 11 | Circuit 15R relay (1) (N10/2kB) | Rear SAM control unit with fuse and relay module (N10/2) | 6 |
| 12 | 12 | Seat ventilation (with code (401) | Front comfort seats, incl. seat heating and seat ventilation) Rear SAM control unit with fuse and relay module (N10/2) | 2.2 |
| 13 | 13 | Seat heater level 3 (with code (873) Seat heater for left and right front seats) | Rear SAM control unit with fuse and relay module (N10/2) | 13.2 |
| 14 | 14 | Rear window heater (R1) | Rear SAM control unit with fuse and relay module (N10/2) | 30.0 |
| 15 | 16 | Seat heater level 2 (with code (873) Seat heater for left and right front seats) | Rear SAM control unit with fuse and relay module (N10/2) | 13.2 |
| 16 | 17 | Seat heater stage 1 (with code (873) Seat heater for left and right front seats) | Rear SAM control unit with fuse and relay module (N10/2) | 3.3 |
| 17 | 20 | Mirror heater (M21/1r1) and mirror heater (M21/2r1) | Left front door control unit (N69/1) and Right front door control unit (N69/2) | 3.5 |
| 18 | 21 | Residual heat utilization (with code (581) Comfort automatic air conditioning and without code (494) USA version) | Automatic air conditioning control and operating unit (N22/7) | 8 |
| Rear automatic air conditioning operating unit (N22/4) (with code (581) Comfort automatic air conditioning) | 6 | |||
| 19 | 22 | Rear dome lamp (E15/3) | Front SAM control unit with fuse and relay module (N10/1) (without code (414) Power glass tilting/sliding sunroof) or Overhead control panel control unit (N70) (with code (414) Power glass tilting/sliding sunroof) |
1 |
| Right trunk lamp (E18/4), left trunk lamp (E18/5) (model 204.2) | Rear SAM control unit with fuse and relay module (N10/2) | 0.5 | ||
| 20 | 23 | Roof sign lamp (E14/4), printer and card reader (with code (965) Electrical preinstallation for rental vehicles) | Special-purpose vehicle multifunction control unit (N26/9) (with code (965) Electrical preinstallation for rental vehicle) |
5 |
| 21 | 24 | Stationary heater (with code (228) Stationary heater) | Stationary heater control unit (A6n1) | 10 |
| 22 | 25 | Radio (A2) (with code (523) MB Audio 20 radio or code (510) Audio 20 incl. CD changer) or Radio with auto pilot system (A2/56) (with code (525) MB Audio 50 APS radio or code (511) Audio 50 APS incl. DVD changer) or COMAND controller unit (A40/3) (with code (527) COMAND APS with single DVD drive (with navigation) or code (512) COMAND incl. DVD changer or code (528) COMAND incl. DVD changer) |
Radio (A2) or Radio with auto pilot system (A2/56) or COMAND controller unit (A40/3) |
2 |
Even when the on-board electrical system voltage is stabilized at a value higher than
U = 11.8 V, consumer shutoff is not revoked. The switched off consumers are not activated again until a reset is made by turning the transmitter key (A8/1) to the circuit 15C ON position.
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 over the interior CAN to the rear SAM control unit.
Function sequence for no-load current management
No-load current management ensures the vehicle's starting capability even after extended idle times. No-load current management is integrated into the rear SAM control unit.
Actuation of the no-load current management relay (F32k2) shuts off consumers that are supplied with power through circuit 30g.
No-load current management however, can accommodate increased power consumption for a specific period after switching off the engine (maximum t = 75 min.). This allows, for example, the radio to be played while the car is being washed.
No-load current management cyclically measures the voltage and power consumption every t = 6 minutes. If an excessively high no-load current is determined for a specific period, the no-load current management relay is opened at the earliest after t = 75 min., but no later than t = 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 engine's starting capability, 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 opening the no-load current switch relay a corresponding signal is sent over the CAN to shutdown the control units. This signal authorizes, e.g. the overhead control panel control unit to move an open tilting/sliding roof to the tilt position.
No-load current management encompasses the following subfunctions:
- Function sequence for no-load current shutoff
- Function sequence for no-load current diagnosis
- No-load current reference value/residual charging current assessment function sequence
Function sequence for no-load current shutoff
No-load current management encompasses the following subfunctions:
- Function sequence for requesting consumer shutoff (no-load current switch)
- Function sequence for shut off consumers
- Function sequence for energize consumers
Function sequence for requesting consumer shutoff (no-load current switch)
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). If the no-load current is too high, the no-load current shutoff relay will be opened at the earliest after t = 75 minutes. The rear SAM control unit reads in the data from the battery sensor over the on-board electrical system LIN (LIN B7) and evaluates it.
If during the waiting time the on-board electrical system voltage falls to
U < 11.8 V drops, 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).
T = 5 min. before opening the no-load current shutoff relay the rear SAM control unit sends a cutoff signal as advance notice to all the control units supplied with power through circuit 30g.
The front SAM control unit sends this cutoff signal over the chassis CAN to the control units connected to the chassis CAN.
The following control units receive the shutoff signal via the interior CAN:
- Instrument cluster (A1)
- Radio (with code (523) MB Audio 20 radio or code (510) Audio 20 with CD changer)
- Radio with auto pilot system (with code (525) MB Audio 50 APS radio or code (511) Audio 50 APS with DVD changer)
- COMAND controller unit
(with code (527) COMAND APS with single DVD drive (with navigation) or code (512) COMAND APS with DVD changer or code (528) COMAND with DVD changer)
- Panoramic sliding sunroof control module (A98)
(with code (413) Panoramic glass sunroof with top sliding sunroof)
- Front SAM control unit
- Automatic air conditioning control and operating unit
- Special-purpose vehicle multifunction control unit
(with code (965) Electrical preinstallation for rental vehicles)
- Trailer recognition control unit
(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)
- Reversing camera control unit (N66/2)
(with code (218) Reversing camera and code (498) Japan version)
- Left front door control unit
- Right front door control unit
- Left rear door control unit (N69/3) (with model 204.0/2/9)
- Right rear door control unit (N69/4) (with model 204.0/2/9)
- 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 switch control unit
- Weight Sensing System (WSS) control unit (N110)
(with model 204.0 up to 28.2.11, model 204.9 up to 31.5.11 and model 204.3 with code (U10) Front passenger seat with weight detection)
- Liftgate control unit (N121/1) (model 204.2/9)
(with code (890) EASY-PACK liftgate)
The following control units receive the shutoff signal over the chassis CAN:
- Supplemental restraint system control unit (N2/10)
- CDI control unit (with diesel engine)
- ME-SFI [ME] control unit (with gasoline engine)
- Parking system control unit (N62)
(with code (220) PARKTRONIC or code (230) Exclusive parking assist)
- Steering column tube module control unit (N80)
- Tire pressure monitor control unit (N88)
(with code (470) Tire pressure monitor (Basis) or code (475) Tire pressure monitor (Premium))
If the interior CAN and chassis CAN are in "sleep mode" during signal transmission, the corresponding control units will be woken up. The 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).
Function sequence for shut off consumers
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 switching status of the no-load current shutoff relay over the interior CAN. The front SAM control unit receives it and sends it over the chassis CAN to the control units connected to the chassis CAN.
Function sequence for energize consumers
The no-load current management closes the no-load current shutoff relay as soon as a system is activated. All the functions are then available again.
The no-load current shutoff relay is opened again when the waiting time of t = 6 h has expired, the on-board electrical system voltage is less than U = 11.8 V or 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 sends it over the chassis CAN to the control units connected to the chassis CAN.
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 antitheft alarm system (ATA [EDW]) is activated (with code (551) Antitheft alarm system (ATA [EDW])):
The waiting time timer is reset.
- The panic alarm is triggered (with code (763) Radio remote control with panic switch):
The waiting time timer is reset.
- Activation of stationary heater (with code (228) stationary heater):
The timer of the waiting time will be reset.
Function sequence for no-load current diagnosis
No-load current diagnosis records data to help troubleshoot possible fault profiles.
The no-load current diagnosis function encompasses the following subfunctions:
D Function sequence for activate no-load current diagnosis
D Function sequence for cancel/end no-load current diagnosis
Additional function requirements for activate no-load current diagnosis
- Circuit 15R OFF
Function sequence for activate no-load current diagnosis
The battery sensor starts the no-load current diagnosis over the on-board electrical system LIN if one of the following events occurs:
- 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. Following this, the no-load current is cyclically checked. These 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
D Circuit 15R ON
D On-board electrical system voltage values fall below limits
Function sequence for cancel/end no-load current diagnosis
No-load current diagnosis will be canceled if the on-board electrical system voltage values fall below the defined limits (U < 11,8 V) 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 quiescent current fault roll.
Additional function requirements for no-load current reference value/residual charging current assessment
- Circuit 30 ON
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 charge current of the on-board electrical system battery.
The no-load current-reference value/residual charging current encompasses the following subfunctions:
- Function sequence for no-load current reference value measurement
- Function sequence for residual charge current assessment
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 "Measure no-load current!" message appears in the instrument cluster's travel distance display (A1p7) (model 204.0/2/3/9/(except 204.077/277/377) without code (442) Comfort multifunction steering wheel) or in the multifunction display (A1p13) (with code (442) Comfort multifunction steering wheel, model 204.077/277/377). 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 travel distance display or in the multifunction display goes out.
If the no-load current reference value is too high, a fault message will be shown in the travel distance indicator or the instrument cluster's multifunction display. Before the quiescent current is measured again, the ignition change from circuit 15C to circuit 15 and back again to circuit 15C must be performed. Finally, the vehicle can be locked again.
Function sequence for residual charge current assessment
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) serves as the measure for a sufficiently charged on-board electrical system battery. This value must be above 80%. If the charge level is less than 80 %, a fault message is shown on the instrument cluster's travel distance display or in the multifunction display.
Measurement of the residual charge 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 for 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 one of the front doors must be opened during a jump start procedure or during any testing in the workshop to enable the alternator management to change to the external starting aid mode or the workshop mode and the alternator voltage to be increased to U = 14.3 V.
| Electrical function schematic for consumer shutoff | PE54.10-P-2066-97FAA | ||
| Overview of system components for energy management | GF54.10-P-9990CE |