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

MODEL 166 as of model year 2016 

MODEL 292 

Function requirements, general 

• "Engine running" or "Drive train operational" signal not set (vehicle switched off)

MODEL 166 (except 166.063) as of model year 2016

MODEL 292

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 "Drive train operational" status via chassis CAN 1 (CAN E1), the electronic ignition lock control unit (N73) and interior CAN (CAN B) to the SAM control unit (N10).

MODEL 166.063 as of model year 2016

The ME-SFI [ME] control unit transmits the status "Engine running" or "Drive train ready" over the engine CAN (CAN C1), the powertrain control unit (N127), chassis CAN 1, the 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 vehicle when the engine is off. 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 subfunctions:

• Consumer shutoff function sequence 
• Function sequence for no-load current management 
• Function sequence for remote charging/jump start 

Additional function requirements for consumer shutoff 

• Circuit 15 ON or Circuit 15R ON

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

Consumer shutoff function sequence 

The SAM control unit actuates the consumer shutoff function under the following conditions:

• On-board electrical system voltage drops below U = 11.8 V (for t = 5 s)
• 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 in the table below.

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	Consumers with reduced or no power	Responsible control unit	Maximum Current in A
1	1	Heating level 6, PTC heater booster (R22/3) (with engine 642.8, 651.9), passenger side	ACC control and operating unit (N22/7)	18, 5
2	2	Heating level 5, PTC heater booster (R22/3) (with engine 642.8, 651.9), driver side	ACC control and operating unit (N22/7)	18, 5
3	3	Heating level 4, PTC heater booster (R22/3) (with engine 642.8, 651.9), passenger side	ACC control and operating unit (N22/7)	18, 5
4	4	Heating level 3, PTC heater booster (R22/3) (with engine 642.8, 651.9), driver side	ACC control and operating unit (N22/7)	18, 5
5	5	Heating level 2, PTC heater booster (R22/3) (with engine 642.8, 651.9), passenger side	ACC control and operating unit (N22/7)	18, 5
6	6	Heating level 1, PTC heater booster (R22/3) (with engine 642.8, 651.9), driver side	ACC control and operating unit (N22/7)	18, 5
7	7	Seat heater stage 3 (with CODE 401 (Climatised seats for driver and front passenger) or with CODE 873 (Seat heater for driver and front passenger))	Driver seat control unit (N32/1) (with CODE 275 (Memory package) over the interior CAN (CAN B), without CODE 275 (Memory package) over the center console switch LIN (LIN B12) connected) and the front passenger seat control unit (N32/2) (with CODE P64 (Memory package) over the interior CAN (CAN B), without CODE P64 (Memory package over the center console switch LIN (LIN B12) connected))	13, 2
8	8	Seat heater stage 2 (with CODE 401 (Climatised seats for driver and front passenger) or with CODE 873 (Seat heater for driver and front passenger))	Driver seat control unit (N32/1) (with CODE 275 (Memory package) over the interior CAN (CAN B), without CODE 275 (Memory package) over the center console switch LIN (LIN B12) connected) and the front passenger seat control unit (N32/2) (with CODE P64 (Memory package) over the interior CAN (CAN B), without CODE P64 (Memory package over the center console switch LIN (LIN B12) connected))	13, 2
9	9	Wiper park position heater (R2/10) via wiper park position heater relay (F58kS)	ACC control and operating unit (N22/7)	15, 0
10	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
11	11	Steering wheel heater (with CODE 443 (Steering wheel heater))	Steering column tube module control unit (N80)	8, 0
12	12	Rear window heater (R1) via rear window heater relay (F4kB)	ACC control and operating unit (N22/7)	30, 0
13	13	Rear blower motor (M2/1) P = 50 %	ACC control and operating unit (N22/7)	5, 5
14	14	Blower motor (A32m1) P = 50 %	ACC control and operating unit (N22/7)	16, 0
15	15	Fan motor (M4/7) P = 50 %	ACC control and operating unit (N22/7)	31, 0
16	16	Circuit 15R2 socket relay (F4kA)	SAM control unit (N10)	6, 0...8, 0
17	18	Seat heater stage 1	Driver seat control unit (N32/1) (with CODE 275 (Memory package) over the interior CAN (CAN B), without CODE 275 (Memory package) over the center console switch LIN (LIN B12) connected) and the front passenger seat control unit (N32/2) (with CODE P64 (Memory package) over the interior CAN (CAN B), without CODE P64 (Memory package over the center console switch LIN (LIN B12) connected))	3, 3
18	19	Use of residual heat without CODE 494 (USA version)	ACC control and operating unit (N22/7)	8, 0
		Rear blower motor (M2/1) P = 0 %	ACC control and operating unit (N22/7)	6, 0
19	20	Stationary heater (with CODE 228 (Stationary heater))	Stationary heater control unit	10, 0
20	21	Radio (A2) (with CODE 505 (Radio 20 NTG5 non-navigation-capable) or with CODE 522 (Audio 20 radio) or COMAND controller unit (A40/3) (with CODE 531 (COMAND APS))	Radio (A2) or 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 not activated again until after a reset of circuit 15C ON.

Additional function requirements for no-load current management 

• Transition from terminal 15R to terminal 15C

The electronic ignition lock control unit sends the status of circuit 15 over the interior CAN to the 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 SAM control unit. Actuation of the circuit 30g relay (F33k1) in the battery compartment prefuse 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 via CAN. This in turn, authorizes e.g. the sliding roof control module (A98/1) to move an open 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 terminal 15R to terminal 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 over 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.

The following control units receive the shutoff signal via the interior CAN:

• Instrument cluster (A1)
• Radio (A2) (with CODE 505 (Radio 20 NTG5 non-navigation-capable) or CODE (522) Audio 20 radio))
• COMAND controller unit (A40/3) with CODE 531 (COMAND APS)
• Panoramic sliding sunroof control unit (A98n1) in panoramic sliding sunroof control module (A98) (with CODE 413 (Panoramic sliding sunroof))
• Sliding roof control module (A98/1)
• ACC control and operating unit (N22/7)
• Trailer recognition control unit (N28/1) (for CODE 550 (Trailer hitch))
• Driver's seat control unit (N32/1) (with CODE 275 (Memory package) connected over interior CAN (CAN B), without CODE 275 (Memory package) over center console switch LIN (LIN B12))
• Front passenger seat control unit (N32/2) (with CODE P64 (Memory package) connected via interior CAN (CAN B), without CODE P64 (Memory package) connected via center console switch LIN (LIN B12))
• Electronic ignition switch control unit
• Liftgate control unit (N121/1) (with CODE 890 (EASY-PACK liftgate))

The radio (A2) with CODE 505 (Radio 20 NTG5 not navigation compatible), with CODE 522 (Audio 20 radio) or the COMAND controller unit (A40/3) with CODE 531 (COMAND APS) sends the switch-off signal over the telematics CAN (CAN A) to the following control units:

• Audio/COMAND display (A40/8)
• Audio/COMAND control panel (A40/9)
• Touchpad (A105) (with CODE 531 (COMAND APS))

The electronic ignition lock control unit sends the shutoff signal over chassis CAN 1 to the following control units and components:

• Left front reversible emergency tensioning retractor (A76)
• Right front reversible emergency tensioning retractor (A76/1)
• Supplemental restraint system control unit (N2/10)
• Electronic Stability Program control unit (N30/4)
• AIRmatic control unit (N51/3) (with CODE 489 (AIRmatic))
• Chassis gateway control unit (N93/7) (with CODE 23P (Driving assistance package PLUS))
• 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:

• Multifunction camera (A40/11) (with CODE 22P (Lane package))
• Reversing camera (B84/3) (with CODE 218 (Reversing camera))
• Parking system control unit (N62) (with CODE 235 (Active Parking Assist))
• Tire pressure monitor control unit (N88) (with CODE 475 (Tire pressure monitor))
• 360° camera control unit (N148) (with CODE 501 (360 degree camera))
• Left headlamp control unit (E1n9) (with CODE 640 (High Performance LED) or CODE 641 (Dynamic left-hand traffic LED headlamp) or CODE 642 (Dynamic right-hand traffic LED headlamp))
• Right headlamp control unit (E2n9) (with CODE 640 (High Performance LED) or CODE 641 (Dynamic left-hand traffic LED headlamp) or CODE 642 (Dynamic right-hand traffic LED headlamp))

The chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)) sends the shutoff signal over the chassis FlexRay (Flex E) to the following control units:

• Radar sensors control unit (N62/1) (for code 23P (Driving assistance package PLUS))
• Stereo multifunction camera (A40/13) (with CODE 23P (Driving assistance package PLUS))

The radio (A2) with CODE 505 (Radio 20 NTG5 not navigation compatible), with CODE 522 (Audio 20 radio) or the COMAND controller unit (A40/3) with CODE 531 (COMAND APS) sends the shutoff signal over the Media Oriented System Transport (MOST) to the following control units

• Tuner unit (A90/4) (with CODE 536 (SIRIUS satellite radio), with CODE 537 (Digital radio (DAB)), with CODE 865 (TV tuner))
• Sound system amplifier control unit (N40/3) (with CODE 810 (Sound system) located under the driver seat, with CODE 811 (Advanced sound system) located in the spare wheel well)

If the telematics CAN, interior CAN, chassis CAN 1, chassis CAN 2, chassis FlexRay and Media Oriented System Transport are in "sleep mode" during signal transmission, the corresponding control units are activated. 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. The SAM control unit sends the status of the relay terminal 30g over the interior CAN, electronic ignition lock control unit and the radio with CODE 505 (Radio 20 NTG5 not navigation compatible), with CODE 522 (Audio 20 radio) or the COMAND controller unit with CODE 531 (COMAND APS) over the telematics CAN, chassis CAN 1, chassis CAN 2 and the Media Oriented System Transport to the corresponding control units.

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 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 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. The electronic ignition lock control unit and the radio (A2) with CODE 505 (Radio 20 NTG5 not navigation compatible), with CODE 522 (Audio 20 radio) or the COMAND controller unit (A40/3) with CODE 531 (COMAND APS) receives this signal and sends it over the telematics CAN, chassis CAN 1, chassis CAN 2 and the Media Oriented System Transport to the corresponding control units. Closing the circuit 30g relay causes power to again be supplied via circuit 30g.

The following conditions authorize a closing of the circuit 30g relay:

• Switching on circuit 15R:

  The timer for the waiting time is reset. The circuit 30g relay remains closed until the status for circuit 15R ON is present.

• Unlocking or opening of a door or the liftgate or switching on circuit 15C:

  The timer for the waiting time is reset.

• Switching on of the hazard warning system, the standing or parking lights or the signaling system of special-purpose vehicles:

  The timer for the waiting time is reset.

• Activation of anti-theft alarm system (ATA [EDW]) (with CODE 551 (Anti-theft alarm system (ATA [EDW]))):

  The timer for the waiting time is reset.

• Triggering of panic alarm:

  The timer for the waiting time is reset.

• Activation of stationary heater (with CODE 228 (Stationary heater)):

The timer for the waiting time is 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:

• 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 

• Terminal 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 quiescent current-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 no-load current fault roll.

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

• Terminal 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:

• 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 system for circuit 15R or higher. The message "Measure no-load current" appears in the multifunction display (A1p13) of the instrument cluster. The diagnostic system 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 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 system.

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.

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 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 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.

If the battery output of the high-voltage battery (A100g1) is extremely low (P < 8 kW) when the hybrid system is being started in model 166.063, starting capability can be achieved by transferring energy from the 12 V on-board electrical system to the high-voltage on-board electrical system.

If an external charger is connected and the power electronics control unit measures a voltage of more than U = 12.8 V in the 12 V-on-board electrical system with the engine hood open, energy with a maximum power of P = 500 W is transferred via on-board electrical system battery and power electronics control unit to the high-voltage on-board electrical system, and the high-voltage battery is charged (only with circuit 15 ON).

Procedure for external charging of on-board electrical system battery 

1. Open cover (1) (slide in direction of arrow) and connect positive terminal of charger to positive terminal point (2).
2. Connect negative terminal of charger to ground point (3).
3. Charge on-board electrical system battery as per operating instructions for charger. Charge on-board electrical system battery in well-ventilated rooms only. Turn on charging unit after connecting it to battery. Turn off charging unit before disconnecting it from battery. Charge on-board electrical system battery with DC only, a charging current of approx. 10 % of the capacity is recommended for the charging process.

Jump starting procedure 

1. Open cover (1) (slide in direction of arrow) and connect positive terminal of jumper cable to positive terminal point (2).
2. Connect positive terminal of jumper cable to positive terminal of jump start battery
3. Connect negative terminal of jumper cable to negative terminal of jump start battery.
4. Connect negative terminal of jumper cable to ground point (3).
5. Start engine. 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 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-2074-97NBA
	Electrical function schematic for comfort function shutoff		PE54.10-P-2076-97NBA
	Overview of energy management system components		GF54.10-P-9990GN