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Volt meter on 2013 Silverado


Best Answer govtech4, 16 May 2013 - 11:28 PM

from 2013 GM service information

 

 

Charging System Description and Operation


 




Electrical Power Management
Overview


The electrical power management system is designed to monitor and control the
charging system and send diagnostic messages to alert the driver of possible
problems with the battery and generator. This electrical power management system
primarily utilizes existing on-board computer capability to maximize the
effectiveness of the generator, to manage the load, improve battery
state-of-charge and life, and minimize the system's impact on fuel economy. The
electrical power management system performs 3 functions:


  • It monitors the battery voltage and estimates the battery condition.

  • It takes corrective actions by boosting idle speeds, and adjusting the
    regulated voltage (if equipped).

  • It performs diagnostics and driver notification.

The battery condition is estimated during ignition-off and during
ignition-on. During ignition-off the state-of-charge of the battery is
determined by measuring the open-circuit voltage. The state-of-charge is a
function of the acid concentration and the internal resistance of the battery,
and is estimated by reading the battery open circuit voltage when the battery
has been at rest for several hours.


The state-of-charge can be used as a diagnostic tool to tell the customer or
the dealer the condition of the battery. Throughout ignition-on, the algorithm
continuously estimates state-of-charge based on adjusted net amp hours, battery
capacity, initial state-of-charge, and temperature.


While running, the battery degree of discharge is primarily determined by a
battery current sensor (if equipped), which is integrated to obtain net amp
hours.


If equipped with a battery current sensor, the electrical power management
function is also designed to perform regulated voltage control to improve
battery state-of-charge, battery life, and fuel economy. This is accomplished by
using knowledge of the battery state-of-charge and temperature to set the
charging voltage to an optimum battery voltage level for recharging without
detriment to battery life.


The Charging System Description and Operation is divided into 3 sections. The
first section describes the charging system components and their integration
into the electrical power management. The second section describes charging
system operation. The third section describes the instrument panel cluster
operation of the charge indicator, driver information center messages, and
voltmeter operation.



Charging System Components

Generator


The generator is a serviceable component. If there is a diagnosed failure of
the generator it must be replaced as an assembly. The engine drive belt drives
the generator. When the rotor is spun it induces an alternating current (AC)
into the stator windings. The AC voltage is then sent through a series of diodes
for rectification. The rectified voltage has been converted into a direct
current (DC) for use by the vehicles electrical system to maintain electrical
loads and the battery charge. The voltage regulator integral to the generator
controls the output of the generator. It is not serviceable. The voltage
regulator controls the amount of current provided to the rotor. If the generator
has field control circuit failure, the generator defaults to an output voltage
of 13.8 V.


 


Body Control Module (BCM)


The body control module (BCM) is a GMLAN device. It communicates with the
engine control module (ECM) and the instrument panel cluster for electrical
power management (electrical power management) operation. The BCM determines the
output of the generator and sends the information to the ECM for control of the
generator turn on signal circuit. It monitors the generator field duty cycle
signal circuit information sent from the ECM for control of the generator. It
monitors a battery current sensor (if equipped), the battery positive voltage
circuit, and estimated battery temperature to determine battery state of charge.
The ECM performs idle boost.


 


Battery Current Sensor (if equipped)


The battery current sensor is a serviceable component that is connected to
the negative battery cable at the battery. The battery current sensor is a
3-wire hall effect current sensor. The battery current sensor monitors the
battery current. It directly inputs to the BCM. It creates a 5-volt pulse width
modulation (PWM) signal of 128 Hz with a duty cycle of 0–100 percent. Normal
duty cycle is between 5–95 percent. Between 0–5 percent and 95–100 percent are
for diagnostic purposes.


 


Engine Control Module (ECM)


When the engine is running, the generator turn-on signal is sent to the
generator from the ECM, turning on the regulator. The generator's voltage
regulator controls current to the rotor, thereby controlling the output voltage.
The rotor current is proportional to the electrical pulse width supplied by the
regulator. When the engine is started, the regulator senses generator rotation
by detecting AC voltage at the stator through an internal wire. Once the engine
is running, the regulator varies the field current by controlling the pulse
width. This regulates the generator output voltage for proper battery charging
and electrical system operation. The generator field duty terminal is connected
internally to the voltage regulator and externally to the ECM. When the voltage
regulator detects a charging system problem, it grounds this circuit to signal
the ECM that a problem exists. The ECM monitors the generator field duty cycle
signal circuit, and receives control decisions based on information from the
BCM.


 


Instrument Panel Cluster


The instrument panel cluster provides the customer notification in case a
concern with the charging system. There are 2 means of notification, a charge
indicator and a driver information center message of SERVICE BATTERY CHARGING
SYSTEM if equipped.


 



Charging System Operation

The purpose of the charging system is to maintain the battery charge and
vehicle loads. There are 6 modes of operation and they include:


  • Battery Sulfation Mode

  • Charge Mode

  • Fuel Economy Mode

  • Headlamp Mode

  • Start Up Mode

  • Voltage Reduction Mode

The engine control module (ECM) controls the generator through the generator
turn ON signal circuit. The ECM monitors the generator performance though the
generator field duty cycle signal circuit. The signal is a pulse width
modulation (PWM) signal of 128 Hz with a duty cycle of 0–100 percent. Normal
duty cycle is between 5–95 percent. Between 0–5 percent and 95–100 percent are
for diagnostic purposes. The following table shows the commanded duty cycle and
output voltage of the generator:









Commanded Duty Cycle



Generator Output Voltage





10%



11 V




20%



11.56 V




30%



12.12 V




40%



12.68 V




50%



13.25 V




60%



13.81 V




70%



14.37 V




80%



14.94 V




90%



15.5 V


The generator provides a feedback signal of the generator voltage output
through the generator field duty cycle signal circuit to the ECM. This
information is sent to the body control module (BCM). The signal is PWM signal
of 128 Hz with a duty cycle of 0–100 percent. Normal duty cycle is between
5–99 percent. Between 0–5 percent and 100 percent are for diagnostic purposes.



Battery Sulfation Mode

The BCM will enter this mode when the interpreted generator output voltage is
less than 13.2 V for 45 minutes. When this condition exists the BCM will enter
Charge Mode for 2–3 minutes. The BCM will then determine which mode to enter
depending on voltage requirements.



Charge Mode

The BCM will enter Charge Mode when ever one of the following conditions are
met.


  • The wipers are ON for than 3 seconds.

  • GMLAN (Climate Control Voltage Boost Mode Request) is true, as sensed by the
    HVAC control head. High speed cooling fan, rear defogger and HVAC high speed
    blower operation can cause the BCM to enter the Charge Mode.

  • The estimated battery temperature is less than 0°C (32°F).

  • Battery State of Charge is less than 80 percent.

  • Vehicle speed is greater than 145 km/h (90 mph)

  • Battery current sensor fault exists (if equipped).

  • System voltage was determined to be below 12.56 V

When any one of these conditions is met, the system will set targeted
generator output voltage to a charging voltage between 13.9–15.5 V, depending on
the battery state of charge and estimated battery temperature.



Fuel Economy Mode

The BCM will enter Fuel Economy Mode when the estimated battery temperature
is at least 0°C (32°F) but less than or equal to 80°C (176°F), the calculated
battery current is less than 15 amperes and greater than −8 amperes, and the
battery state-of-charge is greater than or equal to 80 percent. Its targeted
generator output voltage is the open circuit voltage of the battery and can be
between 12.5–13.1 V. The BCM will exit this mode and enter Charge Mode when any
of the conditions described above are present.



Headlamp Mode

The BCM will enter Headlamp Mode when ever the headlamps are ON (high or low
beams). Voltage will be regulated between 13.9–14.5 V.



Start Up Mode

When the engine is started the BCM sets a targeted generator output voltage
of 14.5 V for 30 seconds.



Voltage Reduction Mode

The BCM will enter Voltage Reduction Mode when the calculated ambient air
temperature is above 0°C (32°F). The calculated battery current is less than
1 ampere and greater than −7 amperes, and the generator field duty cycle is less
than 99 percent. Its targeted generator output voltage is 12.9 V. The BCM will
exit this mode once the criteria are met for Charge Mode.



Auxiliary Battery
Charging (TP2)


The auxiliary battery provision (TP2) can be used to supply electrical power
to additional equipment that the customer may choose to add, such as a slide-in
camper or trailer, without discharging the vehicles primary battery. The
auxiliary battery relay closes when the engine is running, in order to allow the
generator to charge the auxiliary battery. The relay opens when the engine is
off, so that the accessories will not discharge the vehicles primary battery,
which is used for engine starting. If the vehicle is equipped with an auxiliary
battery, the relay will be located on the driver's side of the vehicle, next to
the underhood electrical center. Generally, a fuse should not be used in the
STUD 1 Fuse 68 position of the underhood fuse block, if the vehicle is equipped
with an auxiliary battery. A plastic plug may be installed in this position
instead of a fuse. If a fuse is installed in this position, the accessories will
discharge the primary battery in addition to the auxiliary battery.



Instrument Panel Cluster
Operation


Charge Indicator Operation


The instrument panel cluster illuminates the charge indicator and displays a
warning message in the driver information center if equipped, when the one or
more of the following occurs:


 


  • The engine control module (ECM) detects that the generator output is less
    than 11 V or greater than 16 V. The instrument panel cluster receives a GMLAN
    message from the ECM requesting illumination.

  • The instrument panel cluster determines that the system voltage is less than
    11 V or greater than 16 V for more than 30 seconds. The instrument panel cluster
    receives a GMLAN message from the body control module (BCM) indicating there is
    a system voltage range concern.

  • The instrument panel cluster performs the displays test at the start of each
    ignition cycle. The indicator illuminates for approximately 3 seconds.

Display Message: BATTERY NOT CHARGING SERVICE CHARGING SYSTEM or SERVICE
BATTERY CHARGING SYSTEM


The BCM and the ECM will send a serial data message to the driver information
center for the BATTERY NOT CHARGING SERVICE CHARGING SYSTEM or SERVICE BATTERY
CHARGING SYSTEM message to be displayed. It is commanded ON when a charging
system DTC is a current DTC. The message is turned OFF when the conditions for
clearing the DTC have been met. During cold weather warm-up and extreme
electrical demand , the generator capacity can be briefly exceeded causing this
message to be displayed for up to two minutes.

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11 replies to this topic

#1 JBACA33

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Posted 16 May 2013 - 05:59 PM

I have a 2013 Silverado 1500 with 5.3 engine. The volt guage after starting goes up to about 16 or 17 volts and after about 1 minuite it goes down to about 11 or 12 and then cycles like that back and forth every 2 or 3 minuites. Every other vehicle I have stays pretty much on 14 volts when running.

Does anyone else have this going on with their Silverado?



#2 CDFiXER

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Posted 16 May 2013 - 06:22 PM

Normal. Welcome to the forum.


2013 1500 6.2l LTZ

#3 neilbedwell

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Posted 16 May 2013 - 10:12 PM

Totally freaked me out, too, at first but it is completely normal.  Somebody correct me if I am wrong, but it is my understanding that the computer cycles the alternator voltages up and down based on load in order to save fuel.   



#4 11hennesseysilverado

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Posted 16 May 2013 - 10:13 PM

Hi Johnny, to me that's not normal at all.  Did it do it when you bought the truck ? Or did it just begin ?  It sounds to me like the built in voltage regulator in the alternator is failing.  It's also possible that the battery has an internal short and the alternators regulator is cycling (switching on and off) to control the charge and prevent any damage.  If the battery were suffering some sort of anomaly, the truck would likely seem hard or slow to start.  You shouldn't have to hold the ignition switch on for any longer than a second or so.  Any time you turn on the ignition before you attempt to start the truck, the volt meter should rise to about 12 volts, give or take a half a volt, no more, depending on whether you have a brand new battery or an older one.  Upon starting, depending on the charge status of the battery,  the alternator will start to charge the battery to replenish the amperage (energy) used in starting the motor and gradually rise from 12.5 to 13.5 volts.  Maximum charging voltage should not exceed 14 volts or damage to the battery will result.  While a temporary surge to 15 volts is not normal either, a severely drained battery can draw an initial surge from the alternator but 16-17 volts is abnormal to me. If you take the truck an auto parts store like discount, advance, napa and so forth, most of them have battery and electrical system testers that can be placed on your trucks battery and analyze it's electrical system and status.  Most of them will do it for free.  Or you can go to the dealer since your truck is under warranty and let them diagnose the issue and tell you whether its normal or not.  If they do tell you everything is ok and the response of the meter is normal but you later have a failure, you have proof you took it to them when you first observed  the problem.  That way they can not accuse you of failing to notice a pending problem in a timely manner.  Good luck, enjoy the best truck out there.


Edited by 11hennesseysilverado, 16 May 2013 - 10:15 PM.


#5 11hennesseysilverado

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Posted 16 May 2013 - 10:21 PM

Wow, I just noticed another reply with the same problem.  I own a 2011 LTZ 4x4 CC and mine never has had that issue, and in all my years in tinkering with all sorts of vehicles and boats, I've never seen a normal electrical system rise to over 15 volts on a surge and then bounce back and forth unless it was in trouble.  I would get a reassurance from the selling dealer or your nearest dealer that the issue will not leave you stranded.


Edited by 11hennesseysilverado, 16 May 2013 - 11:04 PM.


#6 11hennesseysilverado

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Posted 16 May 2013 - 10:33 PM

In response to neil's post, I've never heard of the electrical system in a truck or car cycle back and forth to save gas.  It will cycle on and off depending on electrical load to maintain an electrical level of around 13 volts dependng on the amount of accessories in use.  Truck alternators range in size from about 95 amp to about 135 amp based on truck type.  There are heavier duty units and on some trucks up to 2 alternators to meet electrical demand of the vehicle.  It is true though that the more electrical accessories that are in use or on while the engine is running, will cause more resistance and draw a few more horses from the motor to operate, but negligable. Unless you are are a racer who needs every available ounce of torque and horsepower, you won't notice anything.


Edited by 11hennesseysilverado, 16 May 2013 - 11:06 PM.


#7 M. Cueva

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Posted 16 May 2013 - 10:48 PM

Hi Johnny, to me that's not normal at all.  Did it do it when you bought the truck ? Or did it just begin ?  It sounds to me like the built in voltage regulator in the alternator is failing.  It's also possible that the battery has an internal short and the alternators regulator is cycling (switching on and off) to control the charge and prevent any damage.  If the battery were suffering some sort of anomaly, the truck would likely seem hard or slow to start.  You shouldn't have to hold the ignition switch on for any longer than a second or so.  Any time you turn on the ignition before you attempt to start the truck, the volt meter should rise to about 12 volts, give or take a half a volt, no more, depending on whether you have a brand new battery or an older one.  Upon starting, depending on the charge status of the battery,  the alternator will start to charge the battery to replenish the amperage (energy) used in starting the motor and gradually rise from 12.5 to 13.5 volts.  Maximum charging voltage should not exceed 14 volts or damage to the battery will result.  While a temporary surge to 15 volts is not normal either, a severely drained battery can draw an initial surge from the alternator but 16-17 volts is abnormal to me. If you take the truck an auto parts store like discount, advance, napa and so forth, most of them have battery and electrical system testers that can be placed on your trucks battery and analyze it's electrical system and status.  Most of them will do it for free.  Or you can go to the dealer since your truck is under warranty and let them diagnose the issue and tell you whether its normal or not.  If they do tell you everything is ok and the response of the meter is normal but you later have a failure, you have proof you took it to them when you first observed  the problem.  That way they can not accuse you of failing to notice a pending problem in a timely manner.  Good luck, enjoy the best truck out there.

 

 

Sorry, GM has had this charging system for at least 10 years or so. Mine does it but it never goes above 15 and never below 11. It does stay on the lower side (not charging) since I replaced the OEM with a AGM that has way more power (than the acid one ever did). He can take it in and they can test it since it is under warranty but the owner's manual does state that this is normal unless an error message comes on the dash (or light). 


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#8 txab

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Posted 16 May 2013 - 11:03 PM

From  your 2011 manual:

 

When the engine is running, this
gauge shows the condition of the
charging system. The gauge can
transition from a higher to lower or
a lower to higher reading. This is
normal. If the vehicle is operating
outside the normal operating range,
the charging system light comes
on. See Charging System Light on
page 5‑24 for more information.
The voltmeter gauge may also read
lower when in fuel economy mode.
This is normal.

Readings outside the normal
operating range can also occur
when a large number of electrical
accessories are operating in
the vehicle and the engine is
left idling for an extended period.
This condition is normal since the
charging system is not able to
provide full power at engine idle.
As engine speeds are increased,
this condition should correct itself
as higher engine speeds allow the
charging system to create maximum
power.
The vehicle can only be driven for a
short time with the readings outside
the normal operating range. If the
vehicle must be driven, turn off all
accessories, such as the radio and
air conditioner.
Readings outside the normal
operating range indicate a possible
problem in the electrical system.
Have the vehicle serviced as soon
as possible.

 

 

Also the gauges are not meant to be super accurate. They give an overall picture. Plug a scan tool in to find what actual voltages the ECM is seeing. Certainly having the vehicle checked is not a bad idea.

 

 

ETA:  Hey Mike! :seeya:


Edited by txab, 16 May 2013 - 11:06 PM.

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#9 govtech4

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Posted 16 May 2013 - 11:28 PM   Best Answer

from 2013 GM service information

 

 

Charging System Description and Operation


 




Electrical Power Management
Overview


The electrical power management system is designed to monitor and control the
charging system and send diagnostic messages to alert the driver of possible
problems with the battery and generator. This electrical power management system
primarily utilizes existing on-board computer capability to maximize the
effectiveness of the generator, to manage the load, improve battery
state-of-charge and life, and minimize the system's impact on fuel economy. The
electrical power management system performs 3 functions:


  • It monitors the battery voltage and estimates the battery condition.

  • It takes corrective actions by boosting idle speeds, and adjusting the
    regulated voltage (if equipped).

  • It performs diagnostics and driver notification.

The battery condition is estimated during ignition-off and during
ignition-on. During ignition-off the state-of-charge of the battery is
determined by measuring the open-circuit voltage. The state-of-charge is a
function of the acid concentration and the internal resistance of the battery,
and is estimated by reading the battery open circuit voltage when the battery
has been at rest for several hours.


The state-of-charge can be used as a diagnostic tool to tell the customer or
the dealer the condition of the battery. Throughout ignition-on, the algorithm
continuously estimates state-of-charge based on adjusted net amp hours, battery
capacity, initial state-of-charge, and temperature.


While running, the battery degree of discharge is primarily determined by a
battery current sensor (if equipped), which is integrated to obtain net amp
hours.


If equipped with a battery current sensor, the electrical power management
function is also designed to perform regulated voltage control to improve
battery state-of-charge, battery life, and fuel economy. This is accomplished by
using knowledge of the battery state-of-charge and temperature to set the
charging voltage to an optimum battery voltage level for recharging without
detriment to battery life.


The Charging System Description and Operation is divided into 3 sections. The
first section describes the charging system components and their integration
into the electrical power management. The second section describes charging
system operation. The third section describes the instrument panel cluster
operation of the charge indicator, driver information center messages, and
voltmeter operation.



Charging System Components

Generator


The generator is a serviceable component. If there is a diagnosed failure of
the generator it must be replaced as an assembly. The engine drive belt drives
the generator. When the rotor is spun it induces an alternating current (AC)
into the stator windings. The AC voltage is then sent through a series of diodes
for rectification. The rectified voltage has been converted into a direct
current (DC) for use by the vehicles electrical system to maintain electrical
loads and the battery charge. The voltage regulator integral to the generator
controls the output of the generator. It is not serviceable. The voltage
regulator controls the amount of current provided to the rotor. If the generator
has field control circuit failure, the generator defaults to an output voltage
of 13.8 V.


 


Body Control Module (BCM)


The body control module (BCM) is a GMLAN device. It communicates with the
engine control module (ECM) and the instrument panel cluster for electrical
power management (electrical power management) operation. The BCM determines the
output of the generator and sends the information to the ECM for control of the
generator turn on signal circuit. It monitors the generator field duty cycle
signal circuit information sent from the ECM for control of the generator. It
monitors a battery current sensor (if equipped), the battery positive voltage
circuit, and estimated battery temperature to determine battery state of charge.
The ECM performs idle boost.


 


Battery Current Sensor (if equipped)


The battery current sensor is a serviceable component that is connected to
the negative battery cable at the battery. The battery current sensor is a
3-wire hall effect current sensor. The battery current sensor monitors the
battery current. It directly inputs to the BCM. It creates a 5-volt pulse width
modulation (PWM) signal of 128 Hz with a duty cycle of 0–100 percent. Normal
duty cycle is between 5–95 percent. Between 0–5 percent and 95–100 percent are
for diagnostic purposes.


 


Engine Control Module (ECM)


When the engine is running, the generator turn-on signal is sent to the
generator from the ECM, turning on the regulator. The generator's voltage
regulator controls current to the rotor, thereby controlling the output voltage.
The rotor current is proportional to the electrical pulse width supplied by the
regulator. When the engine is started, the regulator senses generator rotation
by detecting AC voltage at the stator through an internal wire. Once the engine
is running, the regulator varies the field current by controlling the pulse
width. This regulates the generator output voltage for proper battery charging
and electrical system operation. The generator field duty terminal is connected
internally to the voltage regulator and externally to the ECM. When the voltage
regulator detects a charging system problem, it grounds this circuit to signal
the ECM that a problem exists. The ECM monitors the generator field duty cycle
signal circuit, and receives control decisions based on information from the
BCM.


 


Instrument Panel Cluster


The instrument panel cluster provides the customer notification in case a
concern with the charging system. There are 2 means of notification, a charge
indicator and a driver information center message of SERVICE BATTERY CHARGING
SYSTEM if equipped.


 



Charging System Operation

The purpose of the charging system is to maintain the battery charge and
vehicle loads. There are 6 modes of operation and they include:


  • Battery Sulfation Mode

  • Charge Mode

  • Fuel Economy Mode

  • Headlamp Mode

  • Start Up Mode

  • Voltage Reduction Mode

The engine control module (ECM) controls the generator through the generator
turn ON signal circuit. The ECM monitors the generator performance though the
generator field duty cycle signal circuit. The signal is a pulse width
modulation (PWM) signal of 128 Hz with a duty cycle of 0–100 percent. Normal
duty cycle is between 5–95 percent. Between 0–5 percent and 95–100 percent are
for diagnostic purposes. The following table shows the commanded duty cycle and
output voltage of the generator:









Commanded Duty Cycle



Generator Output Voltage





10%



11 V




20%



11.56 V




30%



12.12 V




40%



12.68 V




50%



13.25 V




60%



13.81 V




70%



14.37 V




80%



14.94 V




90%



15.5 V


The generator provides a feedback signal of the generator voltage output
through the generator field duty cycle signal circuit to the ECM. This
information is sent to the body control module (BCM). The signal is PWM signal
of 128 Hz with a duty cycle of 0–100 percent. Normal duty cycle is between
5–99 percent. Between 0–5 percent and 100 percent are for diagnostic purposes.



Battery Sulfation Mode

The BCM will enter this mode when the interpreted generator output voltage is
less than 13.2 V for 45 minutes. When this condition exists the BCM will enter
Charge Mode for 2–3 minutes. The BCM will then determine which mode to enter
depending on voltage requirements.



Charge Mode

The BCM will enter Charge Mode when ever one of the following conditions are
met.


  • The wipers are ON for than 3 seconds.

  • GMLAN (Climate Control Voltage Boost Mode Request) is true, as sensed by the
    HVAC control head. High speed cooling fan, rear defogger and HVAC high speed
    blower operation can cause the BCM to enter the Charge Mode.

  • The estimated battery temperature is less than 0°C (32°F).

  • Battery State of Charge is less than 80 percent.

  • Vehicle speed is greater than 145 km/h (90 mph)

  • Battery current sensor fault exists (if equipped).

  • System voltage was determined to be below 12.56 V

When any one of these conditions is met, the system will set targeted
generator output voltage to a charging voltage between 13.9–15.5 V, depending on
the battery state of charge and estimated battery temperature.



Fuel Economy Mode

The BCM will enter Fuel Economy Mode when the estimated battery temperature
is at least 0°C (32°F) but less than or equal to 80°C (176°F), the calculated
battery current is less than 15 amperes and greater than −8 amperes, and the
battery state-of-charge is greater than or equal to 80 percent. Its targeted
generator output voltage is the open circuit voltage of the battery and can be
between 12.5–13.1 V. The BCM will exit this mode and enter Charge Mode when any
of the conditions described above are present.



Headlamp Mode

The BCM will enter Headlamp Mode when ever the headlamps are ON (high or low
beams). Voltage will be regulated between 13.9–14.5 V.



Start Up Mode

When the engine is started the BCM sets a targeted generator output voltage
of 14.5 V for 30 seconds.



Voltage Reduction Mode

The BCM will enter Voltage Reduction Mode when the calculated ambient air
temperature is above 0°C (32°F). The calculated battery current is less than
1 ampere and greater than −7 amperes, and the generator field duty cycle is less
than 99 percent. Its targeted generator output voltage is 12.9 V. The BCM will
exit this mode once the criteria are met for Charge Mode.



Auxiliary Battery
Charging (TP2)


The auxiliary battery provision (TP2) can be used to supply electrical power
to additional equipment that the customer may choose to add, such as a slide-in
camper or trailer, without discharging the vehicles primary battery. The
auxiliary battery relay closes when the engine is running, in order to allow the
generator to charge the auxiliary battery. The relay opens when the engine is
off, so that the accessories will not discharge the vehicles primary battery,
which is used for engine starting. If the vehicle is equipped with an auxiliary
battery, the relay will be located on the driver's side of the vehicle, next to
the underhood electrical center. Generally, a fuse should not be used in the
STUD 1 Fuse 68 position of the underhood fuse block, if the vehicle is equipped
with an auxiliary battery. A plastic plug may be installed in this position
instead of a fuse. If a fuse is installed in this position, the accessories will
discharge the primary battery in addition to the auxiliary battery.



Instrument Panel Cluster
Operation


Charge Indicator Operation


The instrument panel cluster illuminates the charge indicator and displays a
warning message in the driver information center if equipped, when the one or
more of the following occurs:


 


  • The engine control module (ECM) detects that the generator output is less
    than 11 V or greater than 16 V. The instrument panel cluster receives a GMLAN
    message from the ECM requesting illumination.

  • The instrument panel cluster determines that the system voltage is less than
    11 V or greater than 16 V for more than 30 seconds. The instrument panel cluster
    receives a GMLAN message from the body control module (BCM) indicating there is
    a system voltage range concern.

  • The instrument panel cluster performs the displays test at the start of each
    ignition cycle. The indicator illuminates for approximately 3 seconds.

Display Message: BATTERY NOT CHARGING SERVICE CHARGING SYSTEM or SERVICE
BATTERY CHARGING SYSTEM


The BCM and the ECM will send a serial data message to the driver information
center for the BATTERY NOT CHARGING SERVICE CHARGING SYSTEM or SERVICE BATTERY
CHARGING SYSTEM message to be displayed. It is commanded ON when a charging
system DTC is a current DTC. The message is turned OFF when the conditions for
clearing the DTC have been met. During cold weather warm-up and extreme
electrical demand , the generator capacity can be briefly exceeded causing this
message to be displayed for up to two minutes.


How do you write a signature on a laptop screen ??

lmao.


I'm here all week ,try the Veal !!


Rob

#10 txab

txab

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Posted 16 May 2013 - 11:35 PM

That answers that.... :D


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#11 Shaners

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Posted 17 May 2013 - 01:39 PM

I have seen this 4-5 times on my 2013 Avalanche in the first 1500 miles.  Truck is running at idle and full operating temps...  99% of the time it reads 14+ volts.

 

 

 

Attached File  gages.jpg   109.99KB   20 downloads


Edited by Shaners, 17 May 2013 - 01:41 PM.

2013 Avalanche LTZ. White Diamond Tricoat paint w/Ebony leather. (mine)

2005 BMW 645Ci convertible w/only 21k miles

2013 Ford C-Max SEL Hybrid (hers)


Please PM me if you have any questions or concerns.


#12 govtech4

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Posted 17 May 2013 - 08:29 PM

That answers that.... :D

 

 

lmao !!!


How do you write a signature on a laptop screen ??

lmao.


I'm here all week ,try the Veal !!


Rob




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