Engine Off Energy Management, Function - GF54.10-P-1050GW
Model 463 (except 463.342)
as of Model year 2013 up to Model year 2019
Model 463.342
Function requirements, general
- "Engine running or drive train operational not set (vehicle switched off)
The CDI control unit (N3/9) (engine 642) or the ME-SFI control unit (N3/10) (engine 157, 273) sends the "engine running" or "Drive train operational" signal via chassis CAN 1 (CAN E1), the electronic ignition lock control unit (N73) and interior CAN (CAN B) to the SAM control unit (N10).
On vehicles with engine 176, the ME-SFI control unit sends the "engine running" or "Drive train operational" signal via the drive train CAN (CAN C), powertrain control unit (N127), chassis CAN 1, electronic ignition lock control unit and interior CAN to the SAM control unit.
Engine OFF energy management, general
Engine OFF energy management ensures the stability of the on-board electrical system and the starting capability of the engine when the vehicle is parked. This functionality is integrated into the 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 sub-functions:
- Function sequence for consumer reduction (deactivation of convenience functions)
- Function sequence for no-load current management
- Function sequence for remote charging/jump start
Additional function requirement for consumer reduction (deactivation of comfort functions)
- Circuit 15 ON or circuit 15R ON
The electronic ignition lock control unit sends the circuit 15 status over the interior CAN to the SAM control unit.
Function sequence for consumer reduction (deactivation of convenience functions)
If the on-board electrical system voltage drops below U = 11.8V for t = 5 s, the front SAM control unit activates the consumption reduction function (shutoff comfort functions) and sends the request to reduce output or shutoff of consumers to the control units that are connected to the interior CAN over the interior CAN and to the control units that are connected to chassis CAN 1 over the interior CAN, electronic ignition lock control unit and chassis CAN 1.
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 cut off out of the engine ON energy management function (up to shutoff stage 18).
| Sequence | Shutoff stage | Power-reduced or deactivated function | Responsible control unit | Maximum current in A |
|---|---|---|---|---|
| 1 | 7 | Seat heater stage 3 | Driver seat control unit (N32/1) Front passenger seat control unit (N32/2) | 13, 2 |
| 2 | 8 | Seat heater stage 2 | Driver seat control unit (N32/1) Front passenger seat control unit (N32/2) | 13, 2 |
| 3 | 10 | Mirror heater | Left front door control unit (N69/1) Right front door control unit (N69/2) | 3, 5 |
| 4 | 11 | Steering wheel heater (with code VL0 (Heated multifunction steering wheel)) | Steering column tube module control unit (N80) | 8, 0 |
| 5 | 12 | Rear window heater | A/C control and operating unit (N22/7) | 30, 0 |
| 6 | 14 | Blower P = 50 % | A/C control and operating unit (N22/7) | 16, 0 |
| 7 | 15 | Fan P = 50% | A/C control and operating unit (N22/7) | 31, 0 |
| 8 | 18 | Seat heater stage 1 | Driver seat control unit (N32/1) Front passenger seat control unit (N32/2) | 3.3 |
| 9 | 19 | Residual heat utilization | A/C control and operating unit (N22/7) | 8, 0 |
| 10 | 20 | Stationary heater (with code H12 (Stationary heater)) | Stationary heater control unit (A6n1) | 10, 0 |
| 11 | 21 | Audio system | COMAND controller unit (A40/3) | 2, 0 |
Even when the on-board electrical system voltage stabilizes at a value in excess of U = 11.8 V, the consumer shutoff is not canceled. The switched-off consumers are switched on again only after circuit 15C has been switched in. The electronic ignition lock control unit sends the circuit 15 status over the interior CAN to the SAM control unit.
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 SAM control unit.
Function sequence for no-load current management
No-load current management ensures the engine's starting capability even after extended idle times. No-load current management is integrated into the SAM control unit. Actuation of the circuit 30g relay (F33k1) in the battery compartment pre-fuse box (F33) switches off the 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 circuit 30g relay is opened at the earliest after t = 75 minutes, but no later than after t = 6 hours.
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:
- Activation of no-load current management over CAN
- Open the circuit 30g relay
Before the circuit 30g relay is opened a corresponding signal to reduce the power of the control units is transmitted by SAM control unit via CAN.
The no-load current management system comprises the following sub-functions:
- 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
The no-load current shutoff system function comprises the following sub-functions:
- 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 circuit 30g relay will be opened after t = 75 min. The SAM control unit reads in the data from the battery sensor over the battery sensor-LIN (LIN B15) and evaluates it.
If the on-board electrical system voltage drops within the waiting time to U < 11.8 V, the circuit 30g relay is prematurely opened.
If U < 11.8 V, the battery sensor will go into sleep mode (reduced power consumption).
At t = 5 min before the circuit 30g relay is opened, the SAM control unit sends a shutoff signal as advance notice to the corresponding control units supplied with power via circuit 30g. The SAM control unit transmits this cutoff signal via interior CAN.
The following control units receive the shutoff signal via the interior CAN:
- COMAND controller unit (A40/3)
- A/C control and operating unit (N22/7)
- Driver seat control unit (N32/1)
- Front passenger seat control unit (N32/2)
- Electronic ignition switch control unit
The COMAND controller unit sends the shutoff signal via the telematics CAN (CAN A) and Media Oriented System Transport (MOST).
The following control units receive the shutoff signal via the telematics CAN:
- Audio/COMAND display (A40/8)
- Audio/COMAND display (A40/9)
- Digital TV tuner (A90/3) (with code EM8 (TV tuner) and code ZJ1 (Version for Japan))
The following control units receive the shutoff signal via MOST:
- Sound system amplifier control unit (N40/3) (with code EU9 (Harman Kardon® Logic 7® surround sound system))
- Digital Audio Broadcasting control unit (N87/3) (with code EF6
(Digital radio (DAB)))
- Satellite Digital Audio Radio (SDAR) control unit (N87/5) (with code ZU8 (USA national version))
- Media interface control unit (N125/1) (with code EH3 (Media Interface))
The electronic ignition lock control unit sends the shutoff signal over the chassis CAN 1 to the following control units:
- Supplemental Restraint System control unit (N2/10)
- Headlamp range adjustment control unit (N71) (as of production date September 1st, 2015)
- Electronic Stability Program control unit (N30/4)
- Steering column tube module control unit (N80)
The electronic ignition lock control unit sends the shutoff signal over the chassis CAN 2 (CAN E2) to the following control units:
- Parking system control unit (N62) (with code EZ8 (PARKTRONIC))
- Headlamp range adjustment control unit (up to production date August 31st, 2015)
- Tire pressure monitor control unit (N88) (with code RY6 (Tire pressure monitor))
If a CAN is in "sleep mode" during signal transmission, the corresponding control units are 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
After expiry of t = 5 min. the no-load current management opens the circuit 30g relay, provided there has been no reason to shut down in the meantime. For this purpose, the SAM control unit actuates the circuit 30g circuit directly. The SAM control unit then transmits the switching status of the circuit 30g relay via interior CAN.
Detailed information on the signal flow is given in the chapter "Requesting consumer shutoff (no-load current switch)".
Function sequence for energize consumers
The no-load current management closes the circuit 30g relay as soon as a system is activated. All the functions are then available again. The circuit 30g relay is only opened again if the waiting time of t = 6 h has expired, the on-board electrical system voltage is less than U = 11.8V or the no-load current is too high.
If the SAM control unit receives a wake-up signal, the no-load current management closes the circuit 30g relay and signals over the interior CAN that the wake-up conditions for the control units are active again.
Closing the circuit 30g relay causes power to again be supplied via circuit 30g.
Detailed information on the signal flow is given in the chapter "Requesting consumer shutoff (no-load current switch)".
The following conditions authorize a closing of the circuit 30g relay:
- Switching on terminal 15R
- Unlocking or opening of a door or the rear-end door or switching on circuit 15C
- Switching on hazard warning system, standing or parking lights
- Activation of anti-theft alarm system (ATA) (with code FZ5 (Anti-theft alarm system) or code FZ8 (Alarm system))
- Activation of stationary heater (with code H12 (Stationary heater))
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 comprises the following sub-functions:
- Function sequence for activate no-load current diagnosis
- 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 battery sensor-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.
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
- Circuit 15R ON
- On-board electrical system voltage values fall below limits
Function sequence for cancel/end no-load current diagnosis
The no-load current diagnosis is canceled when the limit value (U < 11.8 V) for the on-board electrical system voltage is undershot. 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
- 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 evaluation function comprises the following sub-functions:
- No-load current reference value measurement function sequence
- 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 message "Measure no-load current!" appears in the multifunction display (A1p13) of the instrument cluster (A1). The request for this is sent by the SAM control unit over the interior CAN (except code E11 (Stealth lights with convoy marking)) or over the interior CAN, stealth lights control unit (N1) and the instrument cluster CAN (CAN KI) (with code E11 (Stealth lights with convoy marking)) to the instrument cluster. The diagnostic tester must then be removed and the vehicle locked so that the 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 over the battery sensor LIN to the rear SAM control unit, which then saves it as the no-load current reference value in the 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 goes out. 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.
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 state of charge is below 80%, a fault message will be shown in the multifunction display of the instrument cluster. The request for this is sent by the SAM control unit over the interior CAN (except code E11 (Stealth light with convoy marking)) or over the interior CAN, stealth light control unit and the instrument cluster CAN (with code E11 (Stealth light with convoy marking)) to the instrument cluster.
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.
Charge on-board electrical system battery in well-ventilated rooms only.
During a jump start procedure or during any testing in the workshop, one of the front doors must be opened to enable the alternator management to change to the jump starting mode or the workshop mode and the alternator voltage to be increased to U = 13.9 V.
| Electrical function schematic for no-load current management | PE54.10-P-2074-97ZGA | ||
| Electrical function schematic for comfort function shutoff | PE54.10-P-2076-97ZGA | ||
| Overview of energy management system components | Model 463 (except 463.342) as of Model year 2013 up to Model year 2019 Model 463.342 as of Model year 2013 |
GF54.10-P-9990GW |