"Service Battery Charging System"

G4Bama · May 29, 2015

I own a 2007 Silverado and I have been getting the message " Service Battery Charging System" along with the red battery display. This comes and goes but I have not noticed any performance lose. Another odd thing is that my lights flicker when they are own and the truck is idleing.

I checked the alternator output and it reads between 12.2 - 13.8 depending on the load ie... lights on, high beams on, AC running, cooling fans cycling etc. The battery reads 13.0 - 13.8 with truck running. I used a fluke meter for my voltage readings.

Thanks in advance for advice

DanMan_S · May 29, 2015

My 2009 used to do this. Turns out that the fusible link on the firewall was loose and full of grime. I pulled it apart, cleaned the terminals, coated it in dielectric grease, put it back together and the problem never came back.

gmtech4 · May 29, 2015

Message means there is a code to be pulled and diagnosed

DanMan_S · May 29, 2015

Message means there is a code to be pulled and diagnosed

When I had the problem, there were no codes to be pulled. It didn't give a CEL, and my scan gauge would give the all clear when I would try to read any codes.

G4Bama · May 29, 2015

I did not get a check engine light so there should be no code. This is a puzzling problem. I do not feel that my alternator is bad. We have a company in town who rebuilds alternator so I will take it and have it bench checked.

What is the 3 wire plug attached to the ground wire between the battery and chassis grounding point?

gmtech4 · May 30, 2015

When I had the problem, there were no codes to be pulled. It didn't give a CEL, and my scan gauge would give the all clear when I would try to read any codes.

There IS a code , just not where you're looking , I'm not sure what the computer is called off hand ,CSCM,,Charging System Control Module

Not pulled by a POS scanner

No cel is lit up for this code as it's NOT an engine code

Edited May 30, 2015 by govtech4

G4Bama · May 31, 2015

There is a code somewhere, there is always a code somewhere. Yep there is a code...really?

Back to the original question; who has experienced this issue and what did you do to fix?

gmtech4 · June 1, 2015

There is a code somewhere, there is always a code somewhere. Yep there is a code...really?

Back to the original question; who has experienced this issue and what did you do to fix?

What aren't you getting about the module having a code to have diagnosed , no one is going to chime in as you haven't gotten it scanned for someone to say " ya I had that code " !!!!

Come back with a code and I'll personally look it up for you on my service information

Other than that have a nice day

G4Bama · June 1, 2015

The electrical power management (EPM) 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 EPM 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 EPM 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.

• 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 (SOC) of the battery is determined by measuring the open-circuit voltage. The SOC 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 SOC 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 SOC based on adjusted net amp hours, battery capacity, initial SOC, and temperature.

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

In addition, the EPM function is designed to perform regulated voltage control (RVC) to improve battery SOC, battery life, and fuel economy. This is accomplished by using knowledge of the battery SOC 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 EPM. The second section describes charging system operation. The third section describes the instrument panel cluster (IPC) operation of the charge indicator, driver information center (DIC) 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 volts.

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 (IPC) for electrical power management (EPM) operation. The BCM determines the output of the generator and sends the information to the ECM for control of the generator field control 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, the battery positive voltage circuit, and estimated battery temperature to determine battery state of charge (SOC). The BCM sends idle boost requests to the ECM.

Battery Current Sensor

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)

The ECM directly controls the generator field control circuit input to the generator. The ECM receives control decisions based on messages from the BCM. It monitors the generators generator field duty cycle signal circuit and sends the information to the BCM.

Instrument Panel Cluster (IPC)

The IPC provides a means of customer notification in case of a failure and a voltmeter. There are 2 means of notification, a charge indicator and the driver information center (DIC) SERVICE BATTERY CHARGING SYSTEM message.

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. It monitors the generator performance though the generator field duty cycle signal circuit. The signal is 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. 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 a 5 volt 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 volts 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 more than 3 seconds.

• The 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)

• Current sensor fault exists

• System voltage was determined to be below 12.56 volts

• Tow/Haul mode is enabled

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 volts, depending on the battery state of charge and estimated battery temperature.

Fuel Economy Mode

The BCM will enter Fuel Economy Mode when the ambient air 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 amps and greater than -8 amps, and the battery state of charge (SOC) 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 volts. 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 the headlamps are ON. Voltage will be regulated between 13.9-14.5 volts

Start Up Mode

When the engine is started the BCM sets a targeted generator output voltage of 14.3 volts for 30 seconds.

Voltage Reduction Mode

The BCM will enter Voltage Reduction Mode when the calculated battery temperature is above 0°C (32°F). The calculated battery current is less than 1 amp and greater than -7 amps, and the generator field duty cycle is less than 99 percent. Its targeted generator output voltage is 13 volts. 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 (IPC) Operation

Charge Indicator Operation

The instrument panel cluster (IPC) illuminates the charge indicator and displays a warning message in the driver information center (DIC) when the one or more of the following occurs:

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

• The BCM determines that the system voltage is less than 11 volts or greater than 16 volts.

• The IPC receives a GMLAN message from the body control module (BCM) indicating there is a system voltage range concern.

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

• The ignition is ON, with the engine OFF.

Battery Voltage Gauge Operation

The IPC displays the system voltage as received from the BCM over the GMLAN serial data circuit. If there is no communication with the BCM then the gauge will indicate minimum.

This vehicle is equipped with a regulated voltage control (RVC) system. This system turns off the generator when it is not required in order to improve fuel economy. The generator will turn back on when additional voltage is required. This will cause the voltmeter to fluctuate between 12 and 14 volts as opposed to non-regulated systems which usually maintain a more consistent reading of 14 volts. This fluctuation with the RVC system is normal system operation and NO repairs should be attempted.

SERVICE BATTERY CHARGING SYSTEM

The BCM and the ECM will send a GMLAN message to the DIC for the 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 high electrical demand, the generator capacity can be briefly exceeded causing this message to be displayed for up to two minutes.

As you can see the message "SERVICE BATTERY CHARGING SYSTEM" is the code. This is not my first day troubleshooting a mechanical issue. I have a grasp of the concept, my interest is how other people resolve this issue when it occurred to them.

gmtech4 · June 2, 2015

Woopy !!!! Then fix it tech

ColoradoDave · June 2, 2015

As you can see the message "SERVICE BATTERY CHARGING SYSTEM" is the code. This is not my first day troubleshooting a mechanical issue. I have a grasp of the concept, my interest is how other people resolve this issue when it occurred to them.

The message "Service Battery Charging System" is not the DTC code, its the human readable equivalent of a check engine light for problems that are managed by the BCM. The BCM has interpreted there is a charging problem. This is based on any number of sensors readings the ECM and the BCM use to interpret the health of the charging system, exactly as your research that you posted has shown. Once the BCM determines there is a problem, it will set a DTC. The BCM then sends a message to the DIC (a human readable message...not the actual DTC) so you know there is a problem.

What Rob is saying without specifically saying it is that you'll need something more than an OBDII scanner to read the GM specific code related to this DTC. Because this is not an emission related DTC, DIY handheld scanners will not be able to read the DTC and will report all is fine (as has been noted twice in this thread). Scanners that are able to communicate over the GM bus, have the necessary GM modules loaded and can communicate with modules like the BCM will be able read the actual DTC that is triggering the DIC human readable message you see. You need the DTC code (as well as specific diagnostic procedures related to the DTC) to be able to correctly diagnose the issue, particularly since basic diagnostic work done so far has not found any obvious problems.

Hope this helps.

Edited June 2, 2015 by ColoradoDave

gmtech4 · June 3, 2015

^^^^^^^,I love this guy !!!!!! Lol

00Silverado4x4 · June 3, 2015

It sounds like you have an intermittent connection problem, loose or corroded wire or cable. The code in the computer (hopefully there is one) should give you a better idea of the location that is losing connection. If not, you will need to either have a shop/dealer take a look at it or you will need to start tracing wires and cables from the battery to the alternator and hopefully find the failing connection. Sorry if that doesn't help.

Kapelusprime · June 17, 2015

Noticed my 2011 5.3 was at times as low as 12.5 volts and as high as 14.5 volts at the gage while on the throughway at speeds of 65 and more than a four hour drive.The battery is reading 12 volts why I checked with a multi meter the next day.From what I'm reading this is normal operating for the charging system yes?

I ran a code reader and there are no codes or pending codes.