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GMLAN Signal
Service Battery
Charging System
Indication On
Service Battery
Charging System
Indication On
Service Battery
Charging System
Indication On
Battery Saver
Indication On
Battery Voltage
Indication
B1517.5A
Cluster with DIC
Battery
DIC Message
Telltale
Display
No
No
Low Battery
Voltage
B1517.03
Yes
Service Battery
Charging System
High Battery
Voltage
B1517.07
Yes
Service Battery
Charging System
Battery Current
Sensor
Performance
Current Sensor
Polarity Check
B1516.08
No
No
B1516.66
Yes
Service Battery
Charging System
B1527.00
No
No
-
No
WBattery Saver
Active
B151A.58
No
Low Battery
Parameter
Name
Battery Voltage
Sense Fault
High Parasitic
Load
Energy
Management
Load Shed No3
Low Voltage
DTC
If any DTC is set and if all of the conditions required to set this particular DTC are cleared
(problem corrects itself), after some seconds.
Functional description EPM
The purpose of the Electric Power Management feature is to maintain engine startability and
prevent vehicle failures due to discharged batteries. When the battery State-of-Charge
(SOC) is low, the vehicle’s engine idle speed is increased slightly. When the battery SOC
continues to drop, the rear defog, heated seats, and heated mirrors may be momentarily shut
off. As an extreme measure, when the battery SOC is very low, the A/C compressor and
engine cooling fan after-blow may also be turned off. Once the battery SOC reaches an
appropriate level, these items will be turned back on. These measures should be rarely
visible to the customer, except during the extreme measures.
Normal operation mode
In normal operation mode the system voltage is calculated based on the actual battery
temperature and the SOC. Therefore an array of curves is used, representing optimal
charging conditions.
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Charging Voltage For Different Battery SOCs and Temperatures
16.000
70% SOC
Charging Battery Voltage in Volts
15.500
15.000
80% SOC
14.500
90% SOC
100% SOC
14.000
13.500
13.000
-40
-20
0
20
40
60
80
Estimated Battery Temperature in Degrees C
There are functionalities of the EPM System that cause different voltage behaviors like:
• Start-Up voltage boost
Battery recovers charge lost during cranking it occurs after every ignition cycle and it
lasts 30 seconds
• Headlamp Mode
Purpose of this mode is to maintain optimum headlamp system performance
anytime the EPM system is in any low voltage modes
• Wiper Mode
Purpose of this mode is to maintain optimum wiper system performance anytime the
EPM system is in any low voltage modes
• Sulfation Mode
Battery voltage increase to optimum battery charging voltage for a short time (3-5
minutes) to avoid sulfation. Battery sulfation mode occurs any time the battery
voltage has been at 13V or below for more than 45 minutes.
• Plant Assembly Mode
Improve battery warranty during assembly and while the vehicle is located at the
dealer for the first x miles.
• Voltage Reduction Mode
Voltage reduction mode’s purpose is to reduce the voltage under certain conditions,
anytime the battery is fully charged.
• Fuel Economy Mode
To save fuel, the RVC generator will only provide power to the system if the battery is
fully charged and even drain the battery to a lower SOC in certain conditions
• Climate Control Voltage Boost request
This request will be used if the RVC control algorithm is in Voltage Reduction mode
or in Fuel Economy mode.
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Idle Speed
During periods of high electrical loads and battery discharging, the engine idle speed is
increased to increase the generator output.
The IB noticeability is with respect to Creep Torque, Audible Noise and Vibration. The
maximum degree of noticeability may vary as a function of Resonances, Temperature or
Gear.
• Idle Boost 0 is defined as the normal or base operating mode (with respect to EPM)
with no idle boost requested.
• Idle Boost 1 is defined as the maximum rpm without being noticeable by 95% of all
customers with the engine cooling fans at low speed, the radio off, and the HVAC
blower at medium speed.
• Idle Boost 2 is defined as the maximum rpm without being noticeable by 75% of all
customers with the same loads as for level 1. Thus with the engine cooling fans at
high speed, or the radio on at moderate volume, or the HVAC blower at high speed,
Level 2 will be unnoticeable by more than 75% of all customers. If it is noticeable it
should not be objectionable.
• Idle Boost 3 is defined as the maximum rpm without excessive creep torque. It is
expected to occur very rarely, and to be noticeable by 75% of all customers and it
requires driver notification to prevent warranty claims.
Load Shed
If an increased idle speed doesn’t result in suitable voltages, an additional feature will be
enabled called Load Shedding which will reduced or entirely turned off some certain
electrical loads. The loads that may be reduced or turned off are considered customer
convenience rather than customer safety features.
Examples of loads are:
Heated seats, Heated rear window defogger, Heated exterior mirrors, HVAC blower
• Load Shed 1
Reduces load: HVAC blower
• Load Shed 2
Reduces load: HVAC blower
• Load Shed 3
Turns off: heated seats, heated rear window defogger, heated exterior mirrors,
HVAC blower
If EPM activates Load Shedding Level 3, a message will displayed in the IPC: “Battery Saver
active!
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Exterior Lighting
BCM controls all exterior lights. Beside the conventional switch, there are some additional
features which will be explained below.
Light switch
The position of the switch responsible for exterior lighting is read out by the BCM. There are
four possible states:
Automatic Light
Parking light
Off
Low beam
The connection between “Off” and “Automatic Light” is drawn dashed, because “Off” is a
non latching switch state. The switch will not stay in “Off” position, but go back into
“Automatic Light” position. See section “Automatic light” for details.
Automatic Light
Automatic Light is switched on as default. It can be switched off by turning the light switch
to “Off” position. It will be switched on again by doing so again.
RSM or the ambient light sensor(dashboard mounted) will send the actual ambient light
values to the BCM which then will determine day or night condition and by that adjust
interior and exterior lights automatically to calibrated settings . If the car is equipped with
RSM, a Tunnel Detect feature is also available which will react quicker if car enter a tunnel.
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Lead me to the car
There are 2 version of this feature. The first one is for ROW and second one is for North
America. Both version activates for 30 seconds
First one activates by pressing the “Panic” button (short press) on the UID and cancel by a
second press or a non OFF power mode.
The second version will be automatically activated by pressing “Unlock”button on the UID.
The second one will in addition only activate when BCM detects night condition as it´s
ambient light dependent and cancels by pressing lock button or a non OFF power mode.
The following lamps will be activated:
• Parking Light
• Rear Light
• Reverse Light
• Number plate light
• Low beam
Second version also activates interior light and can be configured off in customization
menu.
Follow me home
If the Power Mode is OFF and the driver door is opened, the driver can activate the flash-topass switch to activate the “Follow me home” feature. BCM will activate the following lights:
• Parking Light
• Rear Light
• Reverse Light
• Number plate light
• Low beam
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Immobilizer
Functional description Immobilizer
The main immobilizer function is performed as an interaction between several modules. The
process that determines whether the engine may be engaged or not consists of several
steps:
1. Key Authentication:
o Every key delivered with the car has been registered in the BCM.
o On key authentication, the transponder code of the key will be read
out by the PEPS system. It is sent to the BCM which compares it to the
registered keys.
2. Vehicle Authentication:
o At end-of-line, pass phrases have been programmed into several
ECUs.
o During the authentication process, BCM sends out a broadcast
message to force some modules to send these keys back. Since BCM
knows the pass phrases either, it is able to compare the received and
stored keys.
o Participating ECUs are EBCM, ECC, IPC and SDM.
o At least three of these modules have to answer within a given time, an
answer of IPC is always required.
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3. ECM Ù BCM Challenge Response:
o ECM sends out a 4 Byte random number (challenge) to the BCM.
o BCM performs a calculation with the challenge (using end-of-line
programmed variables) and sends the converted value back to ECM.
o ECM performs the calculation itself.
o Both results are compared in the ECM. If equal, engine start is
permitted.
If any of these three steps fails, the engine will not start by disabling starter, fuel
injection and spark. In addition, a telltale will indicate the error.
Backup Authentication
If the battery in the Remote Control is empty there is second way to Authenticate the driver
and that is to use the Immobilizer Coil/module which is installed in the arm rest box in
middle console. This coil is used to readout the transponder code of the key. The
information is sent to the BCM.
Connectors and pin assignment Immobilizer Coil
X1
1
2
3
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Pigtail Wire Color
Pigtail Wire Gauge
Return / Ground
Linear Interconnect Network Bus 11
Supply Voltage
Terminal Plating
3277
7533
3276
Shield Group
Circuit Description
Twist Group & Rate
Minimum Wire
Gauge
Max. Wire
Resistance
Circuit #
Cavity
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Interior Lighting
The interior lighting is controlled by the BCM. At first, all controllable lights will be explained.
Subsequently, behavior in every possible state will be described. At the end of the chapter, a
table provides an overview over Interior Lighting Features.
Controllable Interior Lights and Function
Dome lamps
o illuminate the passenger compartment
o activated by Welcome Light and on door open recognition
Spotlight
o shall make it possible to read in dark surrounding of the passenger compartment
o separate control of driver and co-driver spotlight
Rear Passenger Reading Lamp
o shall make it possible to read in dark surrounding of the passenger compartment
Trunk lamp
o illuminates the trunk if opened
Makeup lamp
o shall illuminate the area in front of the makeup mirror
Glove Box light
o illuminates the glove box if opened
Door Handle light
o illuminates the pocket box in the door
PRNDL illumination
Cigarette Lighter
o cigarette lighters provide an illuminated ring
IP switches
o switches not mounted within a faceplate are controlled by the BCM according to
backlight function
Radio switches
o according backlight function
ECC switches
o according backlight function
IPC Backlight
o according backlight function
Main Display (TID, GID, CID)
o activated by:
Radio
Ignition on/off
ECC Display
o activated by Ignition on/off
IPC Display
o activated by opened Driver Door (Odo-only)
o activated by Ignition on/off
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Welcome Light
If the driver unlocks the doors via RF key, welcome light is activated. This means switching
on the dome lamp and puddle lights. Welcome light leads into Theater Dimming if a door is
opened. If no door is opened within a timeout (0…255s, 1s steps, 0: disable), Welcome Light
fades out.
Theater Dimming (IGN off)
In case of “Ignition off” Theater Dimming will be activated, if doors are opened.
Door Open behavior
If a door is opened, interior light will be switched on. BCM differentiates between driver door
and others. On door open recognition, the following lights will be switched on:
driver door
Dome lamps
Mirror puddle light option
Door cortesy light
Footweel light
Ambient light Door handle,
door pocket, footwell, front
dome light area.
• Heart beat Start/Stop Switch
(flashing)
•
•
•
•
•
other doors
• Dome lamps
• Mirror puddle
light (option)
• Door cortesy light
• Footweel light
• Ambient light
Door handle,
door pocket,
footwell, front
dome light area.
Door Close behavior
If a door is closed, the lights will be switched off. There is a difference again between driver
door and others.
When the driver door is closed, the lights will stay on for some time (approx. 20 seconds).
After that time, they will fade out. Within every other door, the lights that have been
switched on will be switched off by fading out immediately.
If the driver switch into > accessory state before the lights went out, they will be switched off
faster
Door open/close light
If a door is opened in “Ignition on” state, dome lamps, Heart beat Start/Stop Switch
(flashing) and puddle light will be switched on. If the doors are closed again, they fade out
immediately.
Inadvertent Load
The following lights are controlled by an inadvertent load relay and will therefore switch off
after some time:
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•
•
•
•
•
Glove Box Light
Sunshade
Dome lamps
Reading lamps
Trailer hook
Door open energy saving (IGN off)
To prevent the battery from running down in “Ignition off” state while the door stays open,
the lights will be switched off after some time. This feature disabled all lamps, in addition to
the Inadvertent Load controlled ones.
Dimming interior lights
Most interior lights are dimmable by the potentiometer mounted left to the IPC:
• IPC
• SWC
• radio display
• radio faceplate
• HVAC faceplate
• top console
• all LEDs installed in the switches
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