Battery Description and Operation
| WARNING | Batteries produce explosive gases, contain corrosive acid, and supply levels of electrical current high enough to cause burns. Therefore, to reduce the risk of personal injury when working near a battery: Always shield your eyes and avoid leaning over the battery whenever possible. Do not expose the battery to open flames or sparks. Do not allow the battery electrolyte to contact the eyes or the skin. Flush immediately and thoroughly any contacted areas with water and get medical help. Follow each step of the jump starting procedure in order. Treat both the booster and the discharged batteries carefully when using the jumper cables. |
Note. Because of the materials used in the manufacture of automotive lead-acid batteries, dealers and service shops that handle them are subject to various regulations issued by OSHA, EPA, DOT, and various state or local agencies. Other regulations may also apply in other locations. Always know and follow these regulations when handling batteries.
Batteries that are no longer wanted must be disposed of by an approved battery recycler and must never be thrown in the trash or sent to a landfill.
Batteries that are not part of the vehicle itself, not the battery under the hood, must only be transported on public streets for business purposes via approved hazardous material transportation procedures.
Battery storage, charging and testing facilities in repair shops must meet various requirements for ventilation, safety equipment, material segregation, etc.
The maintenance free battery is standard. There are no vent plugs in the cover. The battery is completely sealed except for 2 small vent holes in the side. These vent holes allow the small amount of gas that is produced in the battery to escape.
The battery has 3 functions as a major source of energy
- Engine cranking
- Voltage stabilizer
- Alternate source of energy with generator overload
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 alternator. This electrical power management system primarily utilizes existing on-board computer capability to maximize the effectiveness of the alternator, 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.
- It performs diagnostics and driver notification.
The condition of the battery is assessed during ignition on and ignition off. The battery charge status is determined during ignition off by measuring the voltage in the open circuit. 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, which is integrated to obtain net amp hours.
In addition, the electrical power management function is 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 Operation
The purpose of the charging system is to maintain the battery charge and vehicle loads.
The engine control module (ECM) controls the alternator through the alternator turn ON signal circuit. The ECM monitors the alternator performance though the alternator 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 alternator
| Commanded Duty Cycle | Alternator 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 alternator will give a feedback signal as its output voltage to ECM via the signal circuit for alternator field pulse width. 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.
Charge Indicator Operation
The instrument group turns on the charge indicator and displays a warning message in the trip computer when any of the following occurs
- The engine control module (ECM) detects that the alternator 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 IPC performs the display test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.
Starting System Description and Operation
The starter motors are non-repairable starter motors. They have pole pieces that are arranged around the armature. Both solenoid windings are energized. The pull-in winding circuit is completed to the ground through the starter motor. The windings work together magnetically to pull and hold in the plunger. The plunger moves the shift lever. This action causes the starter drive assembly to rotate on the armature shaft spline as it engages with the flywheel ring gear on the engine. Moving at the same time, the plunger also closes the solenoid switch contacts in the starter solenoid. Full battery voltage is applied directly to the starter motor and it cranks the engine.
As soon as the solenoid switch contacts close, current stops flowing thorough the pull-in winding because battery voltage is applied to both ends of the windings. The hold-in winding remains energized. Its magnetic field is strong enough to hold the plunger, shift lever, starter drive assembly, and solenoid switch contacts in place to continue cranking the engine. When the engine starts, pinion overrun protects the armature from excessive speed until the switch is opened.
When the ignition switch is released from the START position, the START relay opens and battery voltage is removed from the starter solenoid S terminal. Current flows from the motor contacts through both windings to the ground at the end of the hold-in winding. However, the direction of the current flow through the pull-in winding is now opposite the direction of the current flow when the winding was first energized.
The magnetic fields of the pull-in and hold-in windings now oppose one another. This action of the windings, along with the help of the return spring, causes the starter drive assembly to disengage and the solenoid switch contacts to open simultaneously. As soon as the contacts open, the starter circuit is turned off.
Keyless Start System Description and Operation
The vehicle has an electronic keyless ignition with push-button start.
Pressing the button cycles it through three positions, ACC/ACCESSORY, ON/RUN/START and OFF.
The transmitter must be in the vehicle for the system to operate. If the push-button start is not working, the vehicle may be near a strong radio antenna signal causing interference to the keyless access system.
To shift out of P (Park), the vehicle must be in ACC/ACCESSORY or ON/RUN and the brake pedal must be applied.
OFF: When this button is pressed with the engine running, the engine will be turned off. If the vehicle is in P (Park), the ignition will turn off, and Retained Accessory Power (RAP) will remain active.
AUT: If the vehicle is not in P (Park), the ignition will return to ACC/ACCESSORY and display the message SHIFT TO PARK in the Driver Information Center (DIC). When the vehicle is shifted into P (Park), the ignition system will switch to OFF. If the vehicle is not shifted into P (Park) it will remain in ACC/ACCESORY for 5 minutes and thereafter it will shift to OFF.
ACC/ACCESSORY: This position allows you to use some electrical accessories when the engine is off. With the ignition off, pressing the button one time without the clutch pedal (MAN) or brake pedal (AUT) applied, will place the ignition system in ACC/ACCESSORY. The ignition will switch from ACC/ACCESSORY to OFF after five minutes to prevent battery run down.
ON/RUN/START: This position is for driving and starting. With the ignition off, and the clutch pedal (MAN) or brake pedal (AUT) applied, pressing the button once will place the ignition system in ON/RUN/START. Once engine cranking begins, release the button. Engine cranking will continue until the engine starts. The ignition will then remain in ON/RUN. To place the ignition in ON/RUN/START from OFF without starting the engine, press the button two times without your foot on the brake pedal. The battery could be drained if you leave the ignition in the ON/RUN/START position with the engine off. You may not be able to start the vehicle if the battery is allowed to drain for an extended period of time.
| DTC | Description |
|---|---|
| DTC B1325 | Device Power Circuit Voltage |
| DTC B1330 | Device Power 2 Circuit Voltage |
| DTC B1517 | Battery Voltage |
| DTC C0800 | Device Power 1 Circuit Voltage |
| DTC P0560 | System Voltage Low |
| DTC P0562 | System Voltage Low |
| DTC P0563 | System Voltage High |
| DTC B1516 | Battery Current Sensor |
| DTC B151A | Low Battery Capacity Detected |
| DTC B1527 | High Parasitic Current Draw Detected |
| DTC P0615 | Starter Relay Control Circuit |
| DTC P0616 | Starter Relay Control Circuit Low Voltage |
| DTC P0617 | Starter Relay Control Circuit High Voltage |
| DTC P0621 | Generator L-Terminal Circuit |
| DTC P0622 | Generator F-Terminal Circuit |
| DTC P0625 | Generator F-Terminal Circuit Low Voltage |
| DTC P0626 | Generator F-Terminal Circuit High Voltage |
| DTC P2500 | Generator L-Terminal Circuit Low Voltage |
| DTC P2501 | Generator L-Terminal Circuit High Voltage |
CHARGING AND STARTING SYSTEM DTC INDEX
Circuit/System Description
The vehicle control modules or sensors monitor the system voltage to verify the system voltage is within the normal operating range.
Description and Operation
CHARGING SYSTEM DESCRIPTION AND OPERATION
The battery current sensor is a 3-wire hall effect current sensor. The body control module (BCM) supplies 5 V and ground to the battery current sensor. The battery current sensor measures the amount of current flowing to or from the battery, and supplies a pulse width modulation (PWM) signal to the BCM.
CHARGING SYSTEM DESCRIPTION AND OPERATION
The body control module (BCM) monitors the battery voltage level during an engine crank event to detect a low battery voltage condition.
CHARGING SYSTEM DESCRIPTION AND OPERATION
The body control module (BCM) monitors the state of charge of the electrical system. If the BCM senses that the state of charge at ignition On is 30 percent lower than what it was when the engine was running.
CHARGING SYSTEM DESCRIPTION AND OPERATION
When the ignition switch is placed in the START position, a discrete signal is supplied to the body control module (BCM) notifying it that the ignition is in the START position. The BCM then sends a message to the engine control module (ECM) that crank has been requested. The ECM then verifies that the clutch pedal is depressed or the transmission is in Park/Neutral. If it is, the ECM then supplies 12 V to the control circuit of the starter motor relay. When this occurs, battery voltage is supplied through the switch of the starter relay to the starter solenoid.
STARTING SYSTEM DESCRIPTION AND OPERATION
The engine control module (ECM) uses the generator turn ON control circuit to control the load of the generator on the engine. A high side driver in the ECM applies a voltage to the voltage regulator. This controls the voltage regulator to turn the field circuit ON and OFF. The ECM monitors the state of the generator turn ON control circuit. The ECM should detect low voltage on generator turn on control circuit when the ignition is ON and the engine is OFF, or when the charging system malfunctions. With the engine running, the ECM should detect high voltage on the generator turn on control circuit.
CHARGING SYSTEM DESCRIPTION AND OPERATION
The engine control module (ECM) uses the generator field duty cycle signal circuit, or F-terminal circuit, to monitor the duty cycle of the generator. The generator field duty cycle signal circuit connects to high side of the field windings in the generator. A pulse width modulated (PWM) high side driver in the voltage regulator turns the field windings ON and OFF. The ECM uses the PWM signal input to determine the generator load on the engine. This allows the ECM to adjust the idle speed to compensate for high electrical loads. The ECM monitors the status of the generator field duty cycle signal circuit. When the ignition is ON and the engine is OFF, the ECM should detect a duty cycle near 0%. When the engine is running, the duty cycle should be between 5-99%.
CHARGING SYSTEM DESCRIPTION AND OPERATION
The engine control module (ECM) uses the generator field duty cycle signal circuit, or F-terminal circuit, to monitor the duty cycle of the generator. The generator field duty cycle signal circuit connects to high side of the field windings in the generator. A pulse width modulated (PWM) high side driver in the voltage regulator turns the field windings ON and OFF. The ECM uses the PWM signal input to determine the generator load on the engine. This allows the ECM to adjust the idle speed to compensate for high electrical loads. The ECM monitors the status of the generator field duty cycle signal circuit. When the ignition is ON and the engine is OFF, the ECM should detect a duty cycle near 0%. When the engine is running, the duty cycle should be between 5-99%.
CHARGING SYSTEM DESCRIPTION AND OPERATION
The engine control module (ECM) uses the generator turn on control circuit, or L-terminal circuit, to control the load of the generator on the engine. A high side driver in the ECM applies a voltage to the voltage regulator. This controls the voltage regulator to turn the field circuit ON and OFF. The ECM monitors the state of the generator turn ON control circuit. The ECM should detect low voltage on generator turn on control circuit when the ignition is ON and the engine is OFF, or when the charging system malfunctions. With the engine running, the ECM should detect high voltage on the generator turn on control circuit. The ECM performs tests to determine the status of the generator turn on control circuit.
CHARGING SYSTEM DESCRIPTION AND OPERATION
STARTING SYSTEM DESCRIPTION AND OPERATION
Components most likely to cause a parasitic draw on the vehicle's battery are switches, relays, and control modules. After the ignition is turned OFF the control modules will begin to go to sleep (shut OFF). All control modules do not go to sleep at the same time, some may take up to 30 minutes or longer after turning the ignition off before going to sleep, like the HVAC and body control modules. Others such as the ON Star and keyless entry control modules may periodically wake up then go back to sleep. These are all normal conditions.
CHARGING SYSTEM DESCRIPTION AND OPERATION
When the ignition switch is placed in the START position, a discrete signal is supplied to the body control module (BCM) notifying it that the ignition is in the START position. The BCM then sends a serial data message to the engine control module (ECM) that crank has been requested. The ECM then verifies that the clutch pedal is fully depressed or the automatic transmission is in Park/Neutral. If it is, the ECM then supplies 12 V to the control circuit of the starter motor relay. When this occurs, battery voltage is supplied through the switch of the starter relay to the starter solenoid.
STARTING SYSTEM DESCRIPTION AND OPERATION
STARTING SYSTEM DESCRIPTION AND OPERATION
STARTING SYSTEM DESCRIPTION AND OPERATION
PG starter motors cannot be repaired. They have pole pieces arranged around the armature. Both solenoid windings are energized. The pull-in winding circuit is completed to the ground through the starter motor. The windings work together magnetically to pull and hold in the plunger. The plunger moves the shift lever. This action causes the starter drive assembly to rotate on the armature shaft spline as it engages with the flywheel ring gear on the engine. Moving at the same time, the plunger also closes the solenoid switch contacts in the starter solenoid. Full battery voltage is applied directly to the starter motor and it cranks the engine.
STARTING SYSTEM DESCRIPTION AND OPERATION