Battery, Charging System and Starting System Cadillac XLR I

Fastener Tightening Specifications

Fastener Tightening Specifications

Battery Usage

Battery Usage

Generator Usage

Generator Usage

Scheme 1

Scheme 2

Scheme 3

Scheme 4

Scheme 5

Scheme 6

Scheme 7

Engine Electrical Connector End Views

Generator (LC3)

Diagnostic Code Index

DIAGNOSTIC CODE INDEX

Diagnostic Starting Point - Engine Electrical

Begin the system diagnosis with Diagnostic System Check - Vehicle . The Diagnostic System Check - Vehicle will provide the following information

1. The identification of the control modules which command the system
2. The ability of the control modules to communicate through the serial data circuit
3. The identification of any stored diagnostic trouble codes (DTCs) and their status

The use of the Diagnostic System Check - Vehicle will identify the correct procedure for diagnosing the system and where the procedure is located.

Scan Tool Output Controls

Scan Tool Output Controls

Scan Tool Data List

Body Control Module (BCM)

Engine Control Module (ECM) 4.4L (LC3)

Engine Control Module (ECM) 4.6L (LH2)

Sensing and Diagnostic Module (SDM)

Transmission Control Module (TCM)

Circuit Description

The body control module (BCM) monitors the battery voltage through the battery voltage signal circuit. Refer to Body Control System Schematics .

A type information accompanies the DTC. Refer to DTC Symptom Description .

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC B1325 Device Power 1 Circuit Voltage

Conditions for Running the DTC

The voltage supplied to the BCM is in the range of 7-26 volts.

Conditions for Setting the DTC

B1325 Type 03

1. The BCM detects a system voltage below 9 volts.
2. The above condition is present at least 5 seconds.

B1325 Type 07

1. The BCM detects a system voltage above 18 volts.
2. The above condition is present at least 5 seconds.

Action Taken When the DTC Sets

1. The BCM immediately disables all outputs when a high voltage condition was detected, with the exception of GMLAN and Run/Crank relay that are disabled after a 3 minutes delay.
2. The setting of other DTCs is inhibited.

Conditions for Clearing the DTC

1. A current DTC clears when the malfunction is no longer present.
2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Diagnostic Aids

1. The following may cause an intermittent: A damaged terminal A backed out terminal A poor terminal tension A chafed wire A broken wire inside the insulation
2. When diagnosing an intermittent short or an open, manipulate the wire harness while watching the test equipment for changes.

DTC B1325

The control modules on this vehicle monitor system voltage through the battery positive voltage circuits. Damage to components, and incorrect data can occur when the voltage is out of range. This vehicle has multiple modules that will set this DTC. For more information on which modules refer to Diagnostic Trouble Code (DTC) List - Vehicle

This diagnostic procedure supports the following DTC

DTC B1327 Device Power 1 Circuit Low

This DTC shall run only if the module has power, ground, and the ignition is not in START mode. This DTC shall execute regardless of the battery voltage.

1. This DTC shall be set as current when the voltage falls below 9 volts for 1.2 seconds.
2. When the vehicle exits START, the module shall delay checking the voltage for 2 seconds.

1. A message shall be sent out to notify all other modules of low battery voltage.
2. The modules disable the setting of U codes and other DTCs.

1. The DTC will clear current status when the voltage is greater than 9.5 volts for 1.2 seconds.
2. A history DTC will clear after 50 consecutive ignition cycles, if the condition for the malfunction is no longer present.
3. Use a scan tool.

DTC B1327

The control modules on this vehicle monitor system voltage through the battery positive voltage circuits. Damage to components, and incorrect data can occur when the voltage is out of range. This vehicle has multiple modules that will set this DTC. For more information on which modules refer to Diagnostic Trouble Code (DTC) List - Vehicle

This diagnostic procedure supports the following DTC

DTC B1328 Device Power 1 Circuit High

This DTC shall run only if the module has power, ground and the ignition is not in START mode. This DTC shall execute regardless of the battery voltage.

This DTC shall be set as current when the voltage raises above 16 volts for 1.2 seconds.

1. A message shall be sent out to notify all other modules of high battery voltage.
2. The modules disable the setting of U codes and other DTCs.

1. The DTC will clear current status when the voltage is less than 15.5 volts for 1.2 seconds.
2. A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
3. Use a scan tool.

DTC B1328

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/xlr/i-2003-2009/remont/oem-general-information/#vehicle-dtc-information) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/xlr/i-2003-2009/remont/oem-general-information/#vehicle-dtc-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/xlr/i-2003-2009/remont/oem-general-information/#vehicle-dtc-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

DTC C0914

Circuit/System Description

The adaptive cruise module (ACM) monitors the system voltage to ensure that the voltage stays within the proper range. Damage to components, and incorrect data may occur when the voltage is out of range.

1. The vehicle speed is above 8 km/h (5 mph).
2. The system voltage is between 9.0-18 volts.

The ACM detects a system voltage below 8.5 volts for 1 second.

1. The ACM will command the RADAR NOT READY warning message to be illuminated on the driver information center (DIC).
2. The Cruise Control will be disabled.

1. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
2. Using the scan tool Clear DTC Information function can clear the DTC.
3. The System Voltage is greater than 9.0 volts.

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

Cruise Control Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

Circuit/System Testing

1. Disconnect the ACM and measure and record the voltage of the battery supply voltage circuit and the ground circuit of the ACM then measure the voltage across battery terminals and compare it with the first reading. Verify that the battery and battery supply voltage circuit do not differ more than 0.8 volts. If more than 0.8 volts test the battery supply voltage, ground circuits of the ACM for high resistance or replace the ACM.
2. Go to «Charging System Test»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__charging-system-test) .

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ACM replacement, setup, and programming

The engine control module (ECM) checks the system voltage to make sure that the voltage stays within the proper range. Damage to components, and incorrect input can occur when the voltage is out of range. The ECM monitors the system voltage over an extended length of time. If the ECM detects an excessively low system voltage, DTC P0562 will set.

This diagnostic procedure supports the following DTC

DTC P0562 System Voltage Low

1. Engine speed above 1500 RPM.
2. System voltage between 9.5-18 volts.

The ECM detects a system voltage below 10 volts for 5 seconds.

1. The ECM will command a message to be displayed.
2. The ECM will not illuminate the malfunction indicator lamp (MIL).
3. The ECM will store conditions which were present when the DTC set as Fail Records data only.

1. The ECM will command the message OFF after one trip in which the diagnostic test has been run and passed.
2. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
3. The DTC can be cleared by using the scan tool Clear DTC Information function.

DTC P0562

The engine control module (ECM) checks the system voltage to make sure that the voltage stays within the proper range. Damage to components, and incorrect input can occur when the voltage is out of range. The ECM monitors the system voltage over an extended length of time. If the ECM detects an excessively high system voltage, DTC P0563 will set.

This diagnostic procedure supports the following DTC

DTC P0563 System Voltage High

1. Engine speed above 1,500 RPM.
2. System voltage between 9.5-18 volts.

The ECM detects a system voltage above 16 volts for less than one second.

1. The ECM will command a message to be displayed.
2. The ECM will not illuminate the malfunction indicator lamp (MIL).
3. The ECM will store conditions which were present when the DTC set as Fail Records data only.

1. The ECM will command the message OFF after one trip in which the diagnostic test has been run and passed.
2. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
3. The DTC can be cleared by using the scan tool Clear DTC Information function.

DTC P0563

The engine control module (ECM) supplies a ground path for the crank relay when start enable has been requested. The ECM monitors this circuit for conditions that are incorrect for the commanded state. If the ECM detects an improper circuit condition, crank relay DTC P0615 will set.

This diagnostic procedure supports the following DTC

DTC P0615 Starter Relay Control Circuit

System voltage is between 9-16 volts.

1. The ECM detects an improper voltage level on the control circuit that controls the crank relay.
2. The condition exists for at least 2 seconds.

1. The ECM will not illuminate the malfunction indicator lamp (MIL)
2. The ECM will store the conditions present when the DTC set as Failure Records data only.

Conditions for Clearing the MIL/DTC

1. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
2. The DTC can be cleared by using the scan tool Clear DTC Information function.

Ignition system DTCs set with the ignition switch in the START position if the crank relay or the starter is inoperative. When the ECM enables starter operation, the ECM also initiates the diagnostic test routines for DTCs P0335, P0340, and P0385. If a condition exists which prevents the engine from cranking, the ECM will not receive signal input from the crankshaft position (CKP) and camshaft position (CMP) sensors, and the DTCs will set.

Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may assist in diagnosing the condition. The information may help determine how often the condition that set the DTC occurs.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 2: Listen for an audible click when the crank relay operates. Press the ignition switch back and forth from the ON to START positions. Repeat this as necessary.
2. 3: This step tests for voltage at the coil side of the crank relay. The ECM IGN fuse supplies power to the coil side of the crank relay.
3. 4: This step verifies that the ECM is providing ground to the crank relay.
4. 5: This step tests if ground is constantly being applied to the crank relay.

DTC P0615

The engine control module (ECM) supplies a ground path for the crank relay when start enable has been requested. The ECM monitors this circuit for conditions that are incorrect for the commanded state. If the ECM detects an improper circuit condition, crank relay DTC P0616 will set.

This diagnostic procedure supports the following DTC

DTC P0616 Starter Relay Control Circuit Low Voltage

1. System voltage is between 8-16 volts.
2. The engine is running.

1. The ECM detects an improper voltage level on the output circuit that controls the crank relay.
2. The condition exists for at least 2 seconds.

1. The ECM will not illuminate the malfunction indicator lamp (MIL).
2. The ECM will store the conditions present when the DTC set as Fail Records data only.

1. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
2. The DTC can be cleared by using the scan tool Clear DTC Information function.

DTC P0616

The engine control module (ECM) supplies a ground path for the crank relay when start enable has been requested. The ECM monitors this circuit for conditions that are incorrect for the commanded state. If the ECM detects an improper circuit condition, crank relay DTC P0616 will set.

This diagnostic procedure supports the following DTC

DTC P0617 Starter Relay Control Circuit High Voltage

1. System voltage is between 8-16 volts.
2. The engine is running.

1. The ECM detects an improper voltage level on the output circuit that controls the crank relay.
2. The condition exists for at least 2 seconds.

1. The ECM will not illuminate the malfunction indicator lamp (MIL).
2. The ECM will store the conditions present when the DTC set as Fail Records data only.

1. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
2. The DTC can be cleared by using the scan tool Clear DTC Information function.

DTC P0617

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/xlr/i-2003-2009/remont/oem-general-information/#vehicle-dtc-information) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/xlr/i-2003-2009/remont/oem-general-information/#vehicle-dtc-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/xlr/i-2003-2009/remont/oem-general-information/#vehicle-dtc-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) uses the generator turn on signal 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 signals the voltage regulator to turn the field circuit ON and OFF. The ECM monitors the state of the generator turn on signal circuit. The ECM should detect low voltage on generator turn on signal 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 signal circuit. The ECM performs key ON and RUN tests to determine the status of the generator turn on signal circuit.

Key ON Test

1. No generator, crankshaft position (CKP) sensors, or camshaft position (CMP) sensor DTCs are set.
2. The ignition is in RUN position.
3. The engine is not running.

Run Test

1. No generator, CKP sensors, CMP sensor DTCs are set.
2. The engine is running.

1. During the key ON test, the ECM detects high voltage on the generator turn on signal circuit for at least 5 seconds.
2. During the RUN test, the ECM detects low voltage on the generator turn on signal circuit for at least 15 seconds.

1. The ECM will command the charge indicator and or warning message to be illuminated on the instrument panel cluster (IPC) and the driver information center (DIC), if equipped.
2. The ECM will not illuminate the malfunction indicator lamp (MIL).
3. The ECM will store conditions, which were present when the DTC set as Failure Records data only.

1. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
2. Using the scan tool Clear DTC Information function can clear the DTC.

On vehicles equipped with a sense circuit connected to the voltage regulator. This circuit must have voltage for the charging system to operate properly. This circuit is used as a reference to control system voltage. All circuits must be tested at the generator before replacing any components. refer to system schematic to confirm if the vehicle being serviced uses the sense circuit as part of the charging system.

Schematic Reference

Starting and Charging Schematics

Connector End View Reference

Engine Electrical Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

Scan Tool Reference

1. «Scan Tool Data List»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__scan-tool-data-list) for ECM
2. «Scan Tool Data Definitions»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) for ECM

1. Ignition OFF, disconnect the harness connector at the generator.
2. Ignition OFF, test for B+ between the generator sense circuit terminal D and ground. If less than the specified range, test the generator sense circuit for a short to ground, an open or a high resistance.
3. Ignition ON, test for less than 1 volt between the generator turn on signal terminal B and ground. If greater than the specified range, test the generator turn on signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Engine Running, test for greater than 3.5 volts between the generator turn on signal and ground. If less than the specified range, test the generator turn on signal circuit for a short to ground, an open or a high resistance. If the circuit tests normal, replace the ECM.
5. If the circuit test normal, replace the generator.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Control Module References»(/cadillac/xlr/i-2003-2009/remont/communication-devices/#computerintegrating-systems__control-module-references) for ECM replacement, setup, and programming
2. «Generator Replacement (LH2)»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Replacement (LC3)»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system)

The engine control module (ECM) uses the generator field duty cycle signal circuit to monitor the duty cycle of the generator. The generator field duty cycle signal circuit connects to the high side of the field winding in the generator. A pulse width modulated (PWM) high side driver in the voltage regulator turns the field winding 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 state of the generator field duty cycle signal circuit. When the key is in the RUN position and the engine is OFF, the ECM should detect a duty cycle near 0 percent. However, when the engine is running, the duty cycle should be between 5 percent and 100 percent. The ECM monitors the PWM signal using a key ON test and a RUN test. During the tests, if the ECM detects an out of range PWM signal, DTC P0622 will set. When the DTC sets, the ECM will send a serial data message to the drivers information center (DIC) to display a warning message.

This diagnostic procedure supports the following DTC

DTC P0622 Generator F-Terminal Circuit

Key ON Test

1. No generator, crankshaft position (CKP) sensors, or camshaft position (CMP) sensor DTCs are set.
2. The key is in the RUN position.
3. The engine is not running.

Run Test

1. No generator, CKP sensors, or CMP sensor DTCs are set.
2. The engine is less than 3,000 RPM.

1. During the key ON test, the ECM detects a PWM signal greater than 65 percent for at least 5 seconds.
2. During the RUN test, the ECM detects a PWM signal less than 5 percent for at least 15 seconds.

1. The ECM will not illuminate the malfunction indicator lamp (MIL).
2. The ECM will store the conditions present when the DTC set as Fail Records data only.

1. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
2. The DTC can be cleared by using the scan tool Clear DTC Information function.

DTC P0622

The engine control module (ECM) uses the generator field duty cycle signal circuit to monitor the duty cycle of the generator and fault indication. The generator field duty cycle signal circuit connects to the high side of the field winding in the generator. A pulse width modulated (PWM) high side driver in the voltage regulator turns the field winding 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 state of the generator field duty cycle signal circuit. When the engine is running, the ECM should detect a duty cycle that varies up to 100 percent. The ECM monitors the PWM signal using a key ON test and a RUN test. During the tests, if the ECM detects an out of range PWM signal, a DTC will set. When the DTC sets, the ECM will send a class 2 serial data message to the instrument panel cluster (IPC) and driver information center (DIC) to illuminate the charge indicator or display a charging message.

This diagnostic procedure supports the following DTC

DTC P0625 Generator F-Terminal Circuit Low Voltage

1. No generator, crankshaft position (CKP) sensors, or camshaft position (CMP) sensor DTCs are set.
2. The engine is less than 3,000 RPM.
3. The generator has not been commanded OFF by the ECM or scan tool.

The ECM detects a PWM signal less than 5 percent for at least 15 seconds.

1. The ECM will not illuminate the malfunction indicator lamp (MIL).
2. The ECM will store the conditions present when the DTC set as Fail Records data only.
3. The ECM will send a class 2 serial data message to the IPC and DIC to illuminate the charge indicator or display a charging message.

1. The conditions for setting DTC P0625 are not present.
2. The DTC can be cleared by using the scan tool Clear DTC Information function.

DTC P0625

The engine control module (ECM) uses the generator field duty cycle signal circuit to monitor the duty cycle of the generator and fault indication. The generator field duty cycle signal circuit connects to the high side of the field winding in the generator. A pulse width modulated (PWM) high side driver in the voltage regulator turns the field winding 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 state of the generator field duty cycle signal circuit. When the key in the ON position, with the engine OFF, the ECM should detect a duty cycle that is 0 percent.

The ECM monitors the PWM signal using a key ON test and a RUN test. During the tests, if the ECM detects an out of range PWM signal, a DTC will set.

This diagnostic procedure supports the following DTC

DTC P0626 Generator F-Terminal Circuit High Voltage

1. No generator, crankshaft position (CKP) sensors, or camshaft position (CMP) sensor DTCs are set.
2. The engine is not running
3. The key is in the ON position

The ECM detects a PWM signal greater than 5 percent for at least 15 seconds.

1. The ECM will not illuminate the malfunction indicator lamp (MIL).
2. The ECM will store the conditions present when the DTC set as Fail Records data only.
3. The ECM will send a class 2 serial data message to the instrument panel cluster (IPC) and driver information center (DIC) to illuminate the charge indicator or display a charging message.

1. The conditions for setting DTC P0626 are not present.
2. The DTC can be cleared by using the scan tool Clear DTC Information function.

DTC P0626

The engine control module (ECM) uses the generator turn-on signal circuit to control the voltage output of the generator. When a different voltage is desired, the ECM will change the pulse width modulation (PWM) signal to the voltage regulator via the generator turn-on signal circuit. This causes the voltage regulator to the voltage output of the generator. The ECM has fault detection circuitry which monitors the state of the generator turn-on signal circuit. If the fault detection circuit senses a voltage other than what is expected, this DTC will set. The voltage regulator also contains fault detection circuitry. If the regulator detects a problem, the regulator will ground the generator turn-on signal circuit, pulling the voltage low. This also causes the ECM to set the DTC.

This diagnostic procedure supports the following DTC

DTC P1668 Generator L-Terminal Control Circuit

Ignition ON Test

1. The ignition is in the ON position for 5 seconds.
2. The engine is OFF.

Engine Run Test

1. The engine is running.
2. The engine speed is less than 3,000 RPM.

Ignition ON Test

1. The ECM detects a high signal voltage on the generator turn on signal circuit for at least 5 seconds.
2. The engine must be started.

During the RUN test, the ECM detects a low signal voltage on the generator turn on signal circuit for at least 5 seconds.

1. The ECM sends a class 2 message to the instrument panel cluster (IPC) to illuminate the charge indicator and/or turn on a message.
2. The ECM will not illuminate the malfunction indicator lamp (MIL).
3. The ECM will store the conditions present when the DTC set as Fail Records data only.

1. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
2. The DTC can be cleared by using the scan tool Clear DTC Information function.

DTC P1668

The engine control module (ECM) uses the generator turn on signal 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 signals the voltage regulator to turn the field circuit ON and OFF. When the ECM turns ON the high side driver, the voltage regulator turns ON the field circuit. When the ECM turns OFF the high side driver, the voltage regulator turns OFF the field circuit.

The ECM monitors the state of the generator turn on signal circuit. With the engine running, the ECM should detect a high generator turn on the signal circuit.

This diagnostic procedure supports the following DTC

DTC P2500 Generator L-Terminal Circuit Low Voltage

1. No generator, crankshaft position (CKP) sensors, or camshaft position (CMP) sensor DTCs are set.
2. The engine is running.
3. The generator has not been commanded OFF by the ECM or scan tool.

The ECM detects a low signal voltage on the generator turn on signal circuit for at least 15 seconds.

1. The ECM will not illuminate the malfunction indicator lamp (MIL).
2. The ECM will store the conditions present when the DTC set as Fail Records data only.
3. The ECM will send a class 2 serial data message to the instrument panel cluster (IPC) and driver information center (DIC) to illuminate the charge indicator or display a charging message.

1. The conditions for setting DTC P2500 are not present.
2. The DTC can be cleared by using the scan tool Clear DTC Information function.

DTC P2500

The engine control module (ECM) uses the generator turn on signal 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 signals the voltage regulator to turn the field circuit ON and OFF. When the ECM turns ON the high side driver, the voltage regulator turns ON the field circuit. When the ECM turns OFF the high side driver, the voltage regulator turns OFF the field circuit.

The ECM monitors the state of the generator turn on signal circuit. The ECM should detect a low generator turn on signal circuit voltage when the key is ON and the engine is OFF, or when the charging system malfunctions. If the ECM detects a high generator turn on signal circuit voltage, DTC P2501 will set.

This diagnostic procedure supports the following DTC

DTC P2501 Generator L-Terminal Circuit High Voltage

1. No generator, crankshaft position (CKP) sensors, or camshaft position (CMP) sensor DTCs are set.
2. The ignition is in the ON position.
3. The engine is not running.

The engine control module (ECM) detects a high signal voltage on the generator turn on signal circuit for at least 5 seconds.

1. The ECM will not illuminate the malfunction indicator lamp (MIL).
2. The ECM will store the conditions present when the DTC set as Fail Records data only.
3. The ECM will send a class 2 serial data message to the instrument panel cluster (IPC) and driver information center (DIC) to illuminate the charge indicator or display a charging message.

1. The conditions for setting DTC P2501 are not present.
2. The DTC can be cleared by using the scan tool Clear DTC Information function.

DTC P2501

Symptoms - Engine Electrical

1. Perform «Diagnostic System Check - Vehicle»(/cadillac/xlr/i-2003-2009/remont/oem-general-information/#vehicle-dtc-information) , before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control modules can communicate via the serial data link.
2. Review the system descriptions and operations in order to familiarize yourself with the system functions. Refer to one of the following system operations: «Battery Description and Operation»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) «Charging System Description and Operation»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) «Load Shed System Description and Operation»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) «Starting System Description and Operation»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__starting-system-description-and-operation)

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the starting and charging systems. Refer to «Checking Aftermarket Accessories»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__checking-aftermarket-accessories) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Battery Inspection/Test»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system)
2. «Battery Electrical Drain/Parasitic Load Test»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system)
3. «Battery Common Causes of Malfunction»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__battery-common-causes-of-malfunction)
4. «Charging System Test»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__charging-system-test)
5. «Charge Indicator Always On»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__charge-indicator-always-on)
6. «Charge Indicator Inoperative»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__charge-indicator-inoperative)
7. «Generator Noise Diagnosis»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system)
8. «Starter Solenoid Does Not Click»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__starter-solenoid-does-not-click)
9. «Starter Solenoid Clicks, Engine Does Not Crank»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__starter-solenoid-clicks-engine-does-not)
10. «Engine Cranks Slowly»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__engine-cranks-slowly)
11. «Starter Motor Noise Diagnosis»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system)

Tools Required

J 42000 Battery Tester. See Special Tools .

Follow these instructions in order to avoid an incorrect diagnosis because of connections

1. If testing the vehicle with the battery cables still connected, wiggle the J 42000 clips on the terminal bolt. See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) . This may cut through any coating or through any oxidation that may be present on the bolt. Even new bolts contain a protective coating that may insulate or cause a resistance in the test circuit.
2. If correct connections to the battery terminal bolts in the vehicle are in doubt, perform the following steps: Disconnect the negative battery cable. Disconnect the positive battery cable. Install the test adapters on the terminals. Follow the instructions for an Out-of-Vehicle test.
3. If the tester displays a REPLACE BATTERY or BAD CELL-REPLACE result for a battery tested in the vehicle with the battery cables connected, perform the following steps: Disconnect the negative battery cable. Disconnect the positive battery cable. Install the tester adapters. Follow the instructions for an Out-of-Vehicle test. Replace the battery only if the Out-of-Vehicle test shows a REPLACE BATTERY or BAD CELL-REPLACE result. This prevents battery replacements that are due only to faulty battery cable connections.
4. Use the correct terminal adapters. Do not use any common bolts or a combination of bolts, nuts, and or washers as adapters when testing the battery. Use the test adapters that are provided with the J 42000 or P/N 12303040 terminal adapters. See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) . If the adapters that are provided with the J 42000 require replacement, use P/N 12303040. See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) . Any other adapter may not contact the correct areas of the battery terminal, causing a resistance that may result in an invalid battery test result.

Battery Inspection/Test

J 42000 Battery Tester. See Special Tools .

1. For best results, use an automatic taper-rate battery charger with a voltage capability of 16 volts.
2. The charging area should be well ventilated.
3. Do not charge a battery that appears to be frozen. Allow the battery to warm to room temperature and test it using the J 42000 before charging. See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) .

Charging Time Required

The time required to charge a battery will vary depending upon the following factors

1. The battery charger capacity-The higher the charger's amperage, the less time it will take to charge the battery.
2. The state-of-charge of the battery-A completely discharged battery requires more than twice as much charging time as a half charged battery. In a discharged battery with a voltage below 11 volts, the battery has a very high internal resistance and may only accept a very low current at first. Later, as the charging current causes the acid content to increase in the electrolyte, the charging current will increase. Extremely discharged batteries may not activate the reversed voltage protection in some chargers. Refer to the manufacturers instructions for operating this circuitry.
3. The temperature of the battery-The colder the battery is, the more time it takes to recharge the battery. The charging current accepted by a cold battery is very low at first. As the battery warms, the charging current will increase.

Charging Procedure

Note. Turn OFF the ignition when connecting or disconnecting the battery cables, the battery charger or the jumper cables. Failure to do so may damage the PCM or other electronic components.

Note. Refer to Fastener Notice .

When charging side-terminal batteries with the battery cables connected, connect the charger to the positive cable bolt and to a ground located away from the battery. When charging side-terminal batteries with the battery cables disconnected, install the battery side terminal adapters and connect the charger to the adapters.

Tighten: Tighten the battery side terminal adapters to 15 N.m (11 lb ft).

Use the following procedure to charge the battery

1. Turn OFF the charger.
2. Ensure that all of the battery terminal connections are clean and tight.
3. Connect the charger positive lead to the battery positive terminal on the battery or fuse block - underhood.
4. Connect the negative charger lead to a solid engine ground or to a ground stud in the engine compartment that is connected directly to the battery negative terminal, but away from the battery. If the negative battery cable is disconnected and a terminal adapter is being used, connect directly to the adapter.
5. Turn ON the charger and set to the highest setting for normal charging.
6. Inspect the battery every half hour after starting the battery charger. Charge the battery until the taper-rate charger indicates that the battery is fully charged. Estimate the battery temperature by feeling the side of the battery. If it feels hot to the touch or its temperature is over 45°C (125°F), discontinue charging and allow the battery to cool before resuming charging.
7. After charging, test the battery. Refer to «Battery Inspection/Test»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .

J 38758 Parasitic Draw Test Switch. See Special Tools .

1. Be sure to rule out any possible obvious influences, such as customer error or aftermarket equipment.
2. Customer driving habits, such as regular short trips. This does not allow enough time to properly charge the battery. Refer to «Battery Description and Operation»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .
3. Verify that the battery and charging system are in proper working order. Refer to «Battery Charging»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) and «Charging System Test»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__charging-system-test) .
4. A battery discharging for no apparent reason while the vehicle is parked can be caused by an intermittent draw, such as a module waking up, or a continuous draw, such as a dome light or stuck relay.
5. Some systems and modules such as OnStar®, and regulated voltage control (RVC), if equipped, are designed to wake-up, perform a task, and go back asleep at regular intervals. Refer to «Body Control System Description and Operation»(/cadillac/xlr/i-2003-2009/remont/communication-devices/#computerintegrating-systems) for the system or modules description and operation.
6. Remote keyless entry (RKE) will wake up due to an outside input. Refer to «Keyless Entry System Description and Operation»(/cadillac/xlr/i-2003-2009/remont/door-locks-anti-theft-systems/#keyless-entry-system) .
7. The graph below indicates roughly how many days a 690 CCA battery with at 110 min. RC (60.5 AH) starting at 80 percent state of charge will last with a constant current draw until it reaches 50 percent state of charge. Differences in battery temperature and ratings will affect the results

Battery Electrical Drain/Parasitic Load Test

Note. Do not turn the parasitic draw test switch to the OFF position with the engine running. Damage will occur to the vehicle's electrical system.

Note. The test switch must be in the ON position when removing the fuses in order to maintain continuity in the electrical system. This avoids damaging the digital multimeter due to accidental overloading, such as a door being opened to change a fuse.

1. Disconnect the battery negative cable from the battery negative terminal.
2. Install the male end of the J 38758 to the battery ground terminal. See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) .
3. Turn the J 38758 knob to the OFF position. See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) .
4. Install the battery negative cable to the female end of the J 38758 . See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) .
5. Turn the J 38758 knob to the ON position. See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) .
6. Road test the vehicle and activate ALL of the accessories, including the radio and air conditioning. This may take up to 30 minutes.
7. Park the vehicle. Turn the ignition switch to the OFF position and remove the ignition switch key.
8. Connect a 10A fused jumper wire to the test switch tool terminals.
9. Turn the J 38758 knob to the OFF position. See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) . The current now flows through the jumper wire.
10. Wait 1 minute. If the fuse blows, install an inductive ammeter and go to step 20.
11. Remove the fused jumper wire.
12. Set a digital multimeter to the 10A scale.
13. Connect the digital multimeter to the test switch tool terminals.
14. Turn the J 38758 knob to the OFF position. See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) . The current flows now through the digital multimeter.
15. Wait 1 minute. Check and record the current reading. When there is a current reading on 2A or less, turn the J 38758 knob to the ON position. See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) . The electrical current will now pass through the switch. Then switch the digital multimeter down to the 2A scale for a more accurate reading when the J 38758 knob is turned OFF. See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) .
16. Turn the J 38758 knob to the OFF position. See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) . Wait 15 minutes for most vehicles.
17. Check and record the current reading.
18. Note the battery Reserve Capacity (Amp Hour rating). Refer to «Battery Usage»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__battery-usage) . Divide the reserve capacity by 4 (Amp hour rating by 2.4). Compare this to the multimeter milliampere reading taken in the previous step. The parasitic current drain should not exceed this number. Example: If a battery has a reserve capacity of 100 minutes, (60 A/H) the current drain should not exceed 25 mA.
19. If excessive current drain is not found at this time and there are no other apparent causes, complete the following: Using the MIN/MAX function of the digital multimeter, monitor the parasitic drain overnight or during the day. This will determine if something has been activated during that time frame. NOTE: The test switch must be in the ON position when removing the fuses in order to maintain continuity in the electrical system. This avoids damaging the digital multimeter due to accidental overloading, such as a door being opened to change a fuse. IMPORTANT: Removing fuses, relays, and connectors to determine the failure area may wake up modules. You must wait for these modules to go to sleep or use the sleep function on the scan tool. When the vehicle has an unacceptable amount of parasitic current drain, remove each fuse one at a time until the current drain falls to an acceptable level. This will indicate which circuit is causing the drain. Refer to «Power Distribution Schematics»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) to diagnose exactly which part of the suspect circuit is causing the parasitic drain. In some cases a non-fused circuit or component, such as a relay, is the cause of excessive parasitic current drain. Repeat the parasitic current drain test procedure after any repair has been completed to make sure that the parasitic current drain is at an acceptable level. When the cause of the excessive current drain has been located and repaired, remove the J 38758 . See «Special Tools»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__special-tools) .
20. Connect the battery negative cable to the battery negative terminal.

Battery Common Causes of Malfunction

A battery is not designed to last forever. With proper care, however, the battery will provide years of good service. If the battery tests good but still fails to perform well, the following are some of the more common causes

1. A vehicle accessory was left on overnight.
2. The driving speeds have been slow with frequent stops, stop-and-go driving, with many electrical accessories in use, particularly air conditioning, headlights, wipers, heated rear window, cellular telephone, etc.
3. The electrical load has exceeded the generator output, particularly with the addition of aftermarket equipment.
4. Existing conditions in the charging system, including the following possibilities: A slipping belt A bad generator
5. The battery has not been properly maintained, including a loose battery hold down or missing battery insulator if used.
6. There are mechanical conditions in the electrical system, such as a short or a pinched wire, attributing to power failure. Refer to «General Electrical Diagnosis»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) .

Electrolyte Freezing

The freezing point of electrolyte depends on its specific gravity. A fully charged battery will not freeze until the ambient temperature gets below -54°C (-65°F). However, a battery with a low state of charge may freeze at temperatures as high as -7°C (20°F). Since freezing may ruin a battery, the battery should be protected against freezing by keeping it properly charged. As long as the green eye is visible in the hydrometer, the freezing point of the battery will be somewhere below -32°C (-25°F).

Battery Protection During Vehicle Storage

Certain devices on the vehicle maintain a small continuous current drain, parasitic load, on the battery. A battery that is not used for an extended period of time will discharge. Eventually permanent damage will result. Discharged batteries will also freeze in cold weather. Refer to Battery Inspection/Test .

In order to maintain the battery state of charge while storing the vehicle for more than 30 days

1. Ensure that the green dot is visible in the built-in hydrometer.
2. Disconnect the battery ground cable to protect the battery from discharge by parasitic current drains.

When the battery cannot be disconnected

1. Maintain a high state of charge.
2. Establish a regular schedule for recharging the battery every 20-45 days.

A battery that has remained in a discharged state for a long period of time is difficult to recharge or may be permanently damaged.

Jump Starting in Case of Emergency

Note. This vehicle has a 12 volt, negative ground electrical system. Make sure the vehicle or equipment being used to jump start the engine is also 12 volt, negative ground. Use of any other type of system will damage the vehicle's electrical components.

1. Position the vehicle with the booster battery so that the jumper cables will reach. Do not let the 2 vehicles touch. Make sure that the jumper cables do not have loose ends, or missing insulation.
2. Place an automatic transmission in PARK. If equipped with a manual transmission, place in NEUTRAL and block the wheels.
3. Turn OFF all electrical loads on both vehicles that are not needed.
4. Turn OFF the ignition on both vehicles.
5. Connect the red positive (+) cable to the battery positive (+) terminal (2) of the vehicle with the discharged battery. Use a remote positive (+) terminal if the vehicle has one.
6. Connect the red positive (+) cable to the positive (+) terminal (1) of the booster battery. Use a remote positive (+) terminal if the vehicle has one.
7. Connect the black negative (-) cable to the negative (-) terminal (3) of the booster battery.
8. The final connection is made to a heavy, unpainted metal engine part (4) of the vehicle with the discharged battery. This final attachment must be at least 46 cm (18 in) away from the dead battery.
9. Start the engine of the vehicle that is providing the boost.
10. Crank the engine of the vehicle with the discharged battery.
11. The black negative (-) cable must be first disconnected from the vehicle that was boosted (4).
12. Disconnect the black negative (-) cable from the negative (-) terminal (3) of the booster battery.
13. Disconnect the red positive (+) cable from the positive (+) terminal (1) of the booster battery.
14. Disconnect the red positive (+) cable from the remote positive (+) terminal (2) of the vehicle with the discharged battery.

Charging System Test

Charging System Test

Charge Indicator Always On

Charge Indicator Always On

Charge Indicator Inoperative

Charge Indicator Inoperative

Noise from a generator may be due to electrical or mechanical noise. Electrical noise or magnetic whine usually varies with the electrical load placed on the generator and is a normal operating characteristic of all generators. When diagnosing a noisy generator, it is important to remember that loose or misaligned components around the generator may transmit the noise into the passenger compartment and that replacing the generator may not solve the problem.

Generator Noise Diagnosis

Starter Solenoid Does Not Click

Starter Solenoid Does Not Click

Starter Solenoid Clicks, Engine Does Not Crank

Starter Solenoid Clicks, Engine Does Not Crank

Engine Cranks Slowly

Inspect the following items

1. Battery-Perform the Battery Inspection/Test. Refer to «Battery Inspection/Test»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .
2. Wiring-Inspect the wiring for damage. Inspect all connections to the starter motor, the solenoid, the battery, and all ground connections. Refer to «Circuit Testing»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing) , «Wiring Repairs»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs) , «Testing for Intermittent Conditions and Poor Connections»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor) , and «Connector Repairs»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs) .
3. Engine-Verify that the engine is not seized.

If the battery, the wiring, and the engine are functioning properly, and the engine continues to crank slowly, replace the starter motor. Refer to Starter Motor Replacement (LH2) or Starter Motor Replacement (LC3) .

Inspect the flywheel ring gear for damage or unusual wear.

Starter Motor Noise Diagnosis

Removal Procedure

1. Record all of the vehicle preset radio stations.
2. Record the radio Theftlock® code (if applicable). Refer to «Radio/Audio System Description and Operation»(/cadillac/xlr/i-2003-2009/remont/entertainment-systems/#entertainment-systems__radioaudio-system-description-and-operation) .
3. Turn OFF all the lamps and the accessories.
4. Make sure the ignition switch is in the OFF position.
5. Loosen the negative battery cable to the battery nut and disconnect the battery negative cable from the battery.

Installation Procedure

1. Connect the battery negative cable to the battery. Tighten: Tighten the negative battery cable to battery nut to 8 N.m (71 lb in).
2. Unlock the Theftlock® radio (if applicable).
3. Program the radio stations back into the radio as recorded at the beginning of the procedure.
4. Set the clock to the current time. Refer to «Radio/Audio System Description and Operation»(/cadillac/xlr/i-2003-2009/remont/entertainment-systems/#entertainment-systems__radioaudio-system-description-and-operation) .
5. Re-initialize both power windows. Refer to «Power Window Reinitialization»(/cadillac/xlr/i-2003-2009/remont/door-locks-anti-theft-systems/#door-system-mirror-system-window-system__power-window-reinitialization) .

1. Disconnect the battery negative cable from the battery. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .
2. Loosen the battery positive cable nut (1) and disconnect the battery positive cable (2) from the battery (3).
3. Open the stud cover on the fuse/relay center.
4. Remove the battery positive cable nut and disconnect the battery positive cable lead from the fuse/relay center stud.
5. Remove the battery cable clips.
6. Remove the battery negative cable to frame rail nut and disconnect the battery negative cable from the frame rail stud.
7. Remove the battery cable bolt (3) securing the battery negative cable (1) and engine harness ground pack (2) to the right rear cylinder head.
8. Remove the intake manifold. Refer to «Intake Manifold Replacement»(/cadillac/xlr/i-2003-2009/remont/mechanical/#engine-mechanical-46l-lh2-1-of-5) .
9. Disconnect the starter jumper wiring harness (2) from the engine harness connector (1).
10. Remove the positive battery cable terminal nut and disconnect the terminals (2) from the starter solenoid.
11. Disconnect the battery positive/starter cable from the generator: Slide the boot (1) back along the cable. Remove the battery positive/starter cable nut (2). Remove the battery positive/starter cable terminal (3) from the stud (4).
12. Remove the positive battery cable routing clip bolt (1) securing the cable and clip to the front of the engine.
13. Remove the battery positive and negative cable assembly.

1. Install the battery positive and negative cable assembly.
2. Connect the battery positive/starter/generator cable to the generator. Install the cable terminal (3) on the generator stud (4). The wire should be between the 2 and 4 o'clock position. Install the terminal nut (2). Tighten: Tighten the generator nut to 20 N.m (15 lb ft). Slide the boot (1) back into place over the stud (4) and the nut (2).
3. Install the positive battery cable routing clip bolt (1) into the cable retaining clip and attach to the front of the engine. Tighten: Tighten the bolt to 35 N.m (26 lb ft).
4. Install the battery positive cable terminals and nut to the starter solenoid. Tighten: Tighten the large nut (2) to 12 N.m (106 lb in). Tighten the small nut to 4 N.m (35 lb in).
5. Connect the starter jumper wiring harness (2) to the engine harness connector (1).
6. Install the intake manifold. Refer to «Intake Manifold Replacement»(/cadillac/xlr/i-2003-2009/remont/mechanical/#engine-mechanical-46l-lh2-1-of-5) .
7. Position the battery negative cable (1) and engine harness ground pack (2) to the right rear cylinder head and install the battery cable bolt (3). Tighten: Tighten the battery positive cable routing clip bolt to 35 N.m (26 lb ft).
8. Position the battery negative cable to frame rail stud and install the negative battery cable to frame rail nut. Tighten: Tighten the battery negative cable to frame rail nut to 11 N.m (97 lb in).
9. Install the battery clips.
10. Position the positive battery cable lead to the fuse/relay center stud and install the positive battery cable nut. Tighten: Tighten the positive battery cable nut to 12 N.m (106 lb in).
11. Close the stud cover on the fuse/relay center.
12. Connect the positive battery cable (2) to the battery (3) and tighten the nut (1). Tighten: Tighten the positive battery cable nut to 8 N.m (71 lb in).
13. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .

1. Disconnect the battery negative cable from the battery. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .
2. Loosen the battery positive cable nut (1) and disconnect the battery positive cable (2) from the battery (3).
3. Open the stud cover on the fuse/relay center.
4. Remove the battery positive cable nut and disconnect the battery positive cable lead from the fuse/relay center stud.
5. Remove the battery cable clips.
6. Remove the battery negative cable to frame rail nut and disconnect the battery negative cable from the frame rail stud.
7. Remove the battery cable bolt (3) securing the battery negative cable (1) and engine harness ground pack (2) to the right rear cylinder head.
8. Remove the supercharger. Refer to «Supercharger Replacement»(/cadillac/xlr/i-2003-2009/remont/mechanical/#engine-mechanical-44l-1-of-5) .
9. Disconnect the starter jumper wiring harness (2) from the engine harness connector (1).
10. Remove the positive battery cable terminal nut and disconnect the terminals (2) from the starter solenoid.
11. Disconnect the battery positive/starter cable from the generator: Slide the boot (1) back along the cable. Remove the battery positive/starter cable nut (2). Remove the battery positive/starter cable terminal (3) from the stud (4).
12. Remove the positive battery cable routing clip bolt (1) securing the cable and clip to the front of the engine.
13. Remove the battery positive and negative cable assembly.

1. Install the battery positive and negative cable assembly.
2. Connect the battery positive/starter/generator cable to the generator. Install the cable terminal (3) on the generator stud (4). The wire should be between the 2 and 4 o'clock position. Install the terminal nut (2). Tighten: Tighten the generator nut to 20 N.m (15 lb ft). Slide the boot (1) back into place over the stud (4) and the nut (2).
3. Install the positive battery cable routing clip bolt (1) into the cable retaining clip and attach to the front of the engine. Tighten: Tighten the bolt to 35 N.m (26 lb ft).
4. Install the battery positive cable terminals and nut to the starter solenoid. Tighten: Tighten the large nut (2) to 12 N.m (106 lb in). Tighten the small nut to 4 N.m (35 lb in).
5. Connect the starter jumper wiring harness (2) to the engine harness connector (1).
6. Install the supercharger. Refer to «Supercharger Replacement»(/cadillac/xlr/i-2003-2009/remont/mechanical/#engine-mechanical-44l-1-of-5) .
7. Position the battery negative cable (1) and engine harness ground pack (2) to the right rear cylinder head and install the battery cable bolt (3). Tighten: Tighten the battery negative cable routing clip bolt to 35 N.m (26 lb ft).
8. Position the battery negative cable to frame rail stud and install the negative battery cable to frame rail nut. Tighten: Tighten the battery negative cable to frame rail nut to 11 N.m (97 lb in).
9. Install the battery clips.
10. Position the positive battery cable lead to the fuse/relay center stud and install the positive battery cable nut. Tighten: Tighten the positive battery cable nut to 12 N.m (106 lb in).
11. Close the stud cover on the fuse/relay center.
12. Connect the positive battery cable (2) to the battery (3) and tighten the nut (1). Tighten: Tighten the positive battery cable nut to 8 N.m (71 lb in).
13. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .

1. Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .
2. Loosen the positive battery cable to the battery nut (1) and disconnect the positive battery cable (2) from the battery (3).
3. Remove the battery hold down retainer bolt (1) and retainer (2).
4. Remove the battery.

1. Install the battery (3).
2. Install the battery hold down retainer (2) and bolt (1). Tighten: Tighten the battery hold down retainer bolt to 18 N.m (13 lb ft).
3. Connect the positive battery cable (2) to the battery (3). Tighten: Tighten the positive battery cable to battery nut to 8 N.m (71 lb in).
4. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .

1. Remove the battery. Refer to «Battery Replacement»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .
2. Remove the battery tray bolts.
3. Remove the battery tray.

1. Install the battery tray.
2. Install the battery tray bolts. Tighten: Tighten the battery tray bolts to 12 N.m (106 lb in).
3. Install the battery. Refer to «Battery Replacement»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .

1. Disconnect the battery negative cable. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .
2. Remove the intake manifold. Refer to «Intake Manifold Replacement»(/cadillac/xlr/i-2003-2009/remont/mechanical/#engine-mechanical-46l-lh2-1-of-5) .
3. Disconnect the BAT cable from the starter.
4. Disconnect the wire from the S terminal (4) on the starter.
5. Remove the 2 starter motor mounting bolts.
6. Remove the starter motor.

1. Install the starter motor.
2. Install the starter motor mounting bolts. Tighten: Tighten the starter motor mounting bolts to 30 N.m (22 lb ft).
3. Connect the starter motor S terminal wire (4). Tighten: Tighten the starter solenoid S terminal nut to 4 N.m (35 lb in).
4. Connect the starter motor BAT terminal wire. Tighten: Tighten the battery cable to starter terminal nut to 12 N.m (106 lb in).
5. Install the intake manifold. Refer to «Intake Manifold Replacement»(/cadillac/xlr/i-2003-2009/remont/mechanical/#engine-mechanical-46l-lh2-1-of-5) .
6. Connect the battery negative cable. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .

1. Disconnect the battery negative cable. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .
2. Remove the supercharger assembly. Refer to «Supercharger Replacement»(/cadillac/xlr/i-2003-2009/remont/mechanical/#engine-mechanical-44l-1-of-5) .
3. Disconnect the battery positive cable from the starter.
4. Disconnect the wire from the S terminal (4) on the starter.
5. Remove the starter motor bolts.
6. Remove the starter motor.

1. Install the starter motor.
2. Install the starter motor bolts. Tighten: Tighten the bolts to 30 N.m (22 lb ft).
3. Connect the wire and nut to the S terminal (4) on the starter. Tighten: Tighten the nut to 4 N.m (35 lb in).
4. Connect the battery positive cable and nut to the starter terminal. Tighten: Tighten the nut to 12 N.m (106 lb in).
5. Install the supercharger assembly. Refer to «Supercharger Replacement»(/cadillac/xlr/i-2003-2009/remont/mechanical/#engine-mechanical-44l-1-of-5) .
6. Connect the battery negative cable. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .

1. Remove the drive belt. Refer to «Drive Belt Replacement»(/cadillac/xlr/i-2003-2009/remont/mechanical/#engine-mechanical-46l-lh2-1-of-5) .
2. Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .
3. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/xlr/i-2003-2009/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) or «Cooling System Draining and Filling (GE 47716)»(/cadillac/xlr/i-2003-2009/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-ge) .
4. Remove the front suspension crossmember. Refer to «Front Suspension Crossmember Replacement»(/cadillac/xlr/i-2003-2009/remont/frames-subframes-crossmembers/#frame-and-underbody) .
5. Remove the bolt from the generator coolant hose assembly on the generator.
6. Disconnect the generator coolant hose assembly from the generator port.
7. Disconnect the generator electrical connector (1).
8. Remove the starter cable terminal from the generator: Slide the boot (1) back along the cable. Remove the starter cable nut (2). Remove the starter cable terminal (3) from the stud (4).
9. Remove the upper generator bolt from the generator.
10. Remove the idler pulley thru-bolt (1).
11. Remove the idler pulley nut (2).
12. Remove the idler pulley assembly (3).
13. Remove the generator (4).

1. Install the generator.
2. Install the upper generator bolt. Tighten: Tighten the generator bolts to 50 N.m (37 lb ft).
3. Install the idler pulley assembly (3) and bolt (1).
4. Install the nut (2). Tighten the generator fasteners to the following torque values: Tighten: Tighten the idler pulley bolt (1) to 50 N.m (37 lb ft). Tighten the idler pulley nut (2) to 50 N.m (37 lb ft).
5. Install the starter cable terminal to the generator: Install the starter cable terminal to the stud. Install the starter cable nut (2). Tighten: Tighten the starter cable nut to 20 N.m (15 lb ft). Slide the boot (1) over the generator stud (4).
6. Position the generator coolant hose assembly to the generator and secure with the bolt. Tighten: Tighten the bolt to 27 N.m (20 lb ft).
7. Connect the generator electrical connector (1).
8. Install the front suspension crossmember. Refer to «Front Suspension Crossmember Replacement»(/cadillac/xlr/i-2003-2009/remont/frames-subframes-crossmembers/#frame-and-underbody) .
9. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/xlr/i-2003-2009/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) or «Cooling System Draining and Filling (GE 47716)»(/cadillac/xlr/i-2003-2009/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-ge) .
10. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .
11. Install the drive belt. Refer to «Drive Belt Replacement»(/cadillac/xlr/i-2003-2009/remont/mechanical/#engine-mechanical-46l-lh2-1-of-5) .

1. Remove the generator drive belt. Refer to «Water Pump and Generator Belt Replacement»(/cadillac/xlr/i-2003-2009/remont/mechanical/#engine-mechanical-44l-1-of-5) .
2. Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .
3. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/xlr/i-2003-2009/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) or «Cooling System Draining and Filling (GE 47716)»(/cadillac/xlr/i-2003-2009/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-ge) .
4. Remove the front suspension crossmember. Refer to «Front Suspension Crossmember Replacement»(/cadillac/xlr/i-2003-2009/remont/frames-subframes-crossmembers/#frame-and-underbody) .
5. Remove the bolt from the generator coolant hose assembly on the generator.
6. Disconnect the generator coolant hose assembly from the generator port.
7. Disconnect the generator electrical connector (1).
8. Remove the starter cable terminal from the generator: Slide the boot (1) back along the cable. Remove the starter cable nut (2). Remove the starter cable terminal (3) from the stud (4).
9. Remove the upper generator bolt from the generator.
10. Remove the idler pulley thru-bolt (1).
11. Remove the idler pulley nut (2).
12. Remove the idler pulley assembly (3).
13. Remove the generator (4).

1. Install the generator.
2. Install the upper generator bolt. Tighten: Tighten the generator bolts to 50 N.m (37 lb ft).
3. Install the idler pulley assembly (3) and bolt (1).
4. Install the nut (2). Tighten the generator fasteners to the following torque values: Tighten: Tighten the idler pulley bolt (1) to 50 N.m (37 lb ft). Tighten the idler pulley nut (2) to 50 N.m (37 lb ft).
5. Install the starter cable terminal to the generator: Install the starter cable terminal to the stud. Install the starter cable nut (2). Tighten: Tighten the starter cable nut to 20 N.m (15 lb ft). Slide the boot (1) over the generator stud (4).
6. Position the generator coolant hose assembly to the generator and secure with the bolt. Tighten: Tighten the bolt to 27 N.m (20 lb ft).
7. Connect the generator electrical connector (1).
8. Install the front suspension crossmember. Refer to «Front Suspension Crossmember Replacement»(/cadillac/xlr/i-2003-2009/remont/frames-subframes-crossmembers/#frame-and-underbody) .
9. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/xlr/i-2003-2009/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) or «Cooling System Draining and Filling (GE 47716)»(/cadillac/xlr/i-2003-2009/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-ge) .
10. Connect the negative battery cable (2). Refer to «Battery Negative Cable Disconnection and Connection»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) .
11. Install the generator drive belt. Refer to «Water Pump and Generator Belt Replacement»(/cadillac/xlr/i-2003-2009/remont/mechanical/#engine-mechanical-44l-1-of-5) .

Scheme 8

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

1. Engine cranking
2. Voltage stabilizer
3. Alternate source of energy with generator overload

The battery specification label, example below, contains information about the following

1. The test ratings
2. The original equipment catalog number
3. The recommended replacement model number

Scheme 9

Battery Ratings

A battery may have 3 ratings

1. Amp hour
2. Reserve capacity
3. Cold cranking amperage

When a battery is replaced, use a battery with similar ratings. Refer to the battery specification label on the original battery or refer to Battery Usage .

Amp Hour

The amp hour rating of a battery is the amount of time it takes a fully charged battery, being discharged at a constant rate of 1 amperes and a constant temperature of 27°C (80°F), to reach a terminal voltage of 10.5 volts. Refer to Battery Usage for the amp hour rating of the original equipment battery.

Reserve Capacity

Reserve capacity is the amount of time in minutes it takes a fully charged battery, being discharged at a constant rate of 25 amperes and a constant temperature of 27°C (80°F), to reach a terminal voltage of 10.5 volts. Refer to Battery Usage for the reserve capacity rating of the original equipment battery.

Cold Cranking Amperage

The cold cranking amperage is an indication of the ability of the battery to crank the engine at cold temperatures. The cold cranking amperage rating is the minimum amperage the battery must maintain for 30 seconds at -18°C (0°F) while maintaining at least 7.2 volts. Refer to Battery Usage for the cold cranking amperage rating for this vehicle.

Generator

The generator features the following major components

1. The delta stator
2. The rectifier bridge
3. The rotor with slip rings and brushes
4. A conventional pulley
5. The regulator

The slip ring and the frame are liquid cooled.

The generator features permanently lubricated bearings. Service should only include tightening of mount components. Otherwise, replace the generator as a complete unit.

Regulator

The voltage regulator controls the rotor field current in order to limit the system voltage. When the field current is on, the regulator switches the current on and off at a rate of 400 cycles per second in order to perform the following functions

1. Radio noise control
2. Obtain the correct average current needed for proper system voltage control

At high speeds, the on-time may be 10 percent with the off-time at 90 percent. At low speeds, the on-time may be 90 percent and the off-time 10 percent.

The generator provides voltage to operate the vehicle's electrical system and to charge its battery. A magnetic field is created when current flows through the rotor. This field rotates as the rotor is driven by the engine, creating an AC voltage in the stator windings. The AC voltage is converted to DC by the rectifier bridge and is supplied to the electrical system at the battery terminal.

When the engine is running, the generator turn-on signal is sent to the generator from the engine control module (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 F 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. The system voltage sense circuit receives B+ voltage that is Hot At All Times through the HORN/ALT SENSE fuse in the underhood junction block. This voltage is used by the regulator as the reference for system voltage control. On vehicles that use a sense circuit connected to the voltage regulator, this circuit must be operating properly for the charging system to work correctly, when there is a charging system concern all circuits at the generator should be tested.

Charging System Messages

The driver information center (DIC) displays a charging system message the when the following occurs

1. The engine control module (ECM) detects that the generator output is less than 11 volts or greater than 16 volts. The DIC receives a class 2 message from the ECM requesting illumination of the charge charging system message.
2. The instrument panel cluster (IPC) determines that the system voltage is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the body control module (BCM) indicating the system voltage.

CHARGE SYSTEM FAULT

The DIC displays the CHARGE SYSTEM FAULT message when the ECM detects a malfunction with the generator output. The IPC receives a message from the ECM requesting illumination.

BATTERY SAVER ACTIVE

The DIC displays the BATTERY SAVER ACTIVE message when the BCM reduces or disables the performance of some vehicle systems in order to reduce the load on the charging system. The DIC receives a message from the BCM requesting illumination.

VOLTAGE HIGH

The DIC displays the VOLTAGE HIGH message when the IPC determines that the system voltage is greater than 16 volts. The IPC receives a message from the BCM indicating the system voltage.

VOLTAGE LOW

The DIC displays the VOLTAGE LOW message when the IPC determines that the system voltage is less than 11 volts. The IPC receives a message from the BCM indicating the system voltage.

SERVICE CHARGING SYS

The DIC displays the SERVICE CHARGING SYS message when the ECM detects a malfunction with the generator output. The IPC receives a message from the ECM requesting illumination.

Starting System Description and Operation

The starter motors on this vehicle are non-repairable. It has 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 engine control module (ECM) sees an engine run flag, the ground is removed from the control circuit of the crank relay. The switch side of the crank 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.

Pressing the Start switch sends a discrete input to the body control module (BCM) notifying it that engine start has been requested. The BCM then verifies that the brake pedal has been depressed with a discrete input from the break pedal switch and that the key fob, with the correct code, is in the vehicle. After this information has been verified the BCM grounds the control side of the RUN/CRANK Relay closing the switch side of it and allowing battery positive voltage to flow from the BATT 3 fuse through the RUN/CRANK Relay switch, ECM Fuse to the battery positive voltage side of the crank relay coil. The BCM also sends a high speed GMLAN message to the ECM requesting engine start. The ECM will then verify that the internal mode switch (IMS) is in Park of Neutral. After this has been verified the ECM grounds the control circuit of the CRANK relay closing the CRANK relay switch circuit and allowing battery positive voltage to flow through the STARTER Fuse, the CRANK relay switch to the S terminal of the Starter solenoid cranking the engine. Ground is supplied through the engine block.

Electrical Load Management

Electrical load management is designed to maintain battery voltage and covers more than load-shed. The body control module (BCM) will request increases in idle speed from the engine control module (ECM), when the vehicle is in park or neutral, as well as turn off loads in order to manage the electrical system and preserve the vehicle electrical power availability. The BCM calculates the battery temperature, voltage and charging rate at all times while the engine is running.

The BCM calculates the battery temperature by factoring in

1. The current intake manifold air temperature compared to the last temperature recorded when the ignition switch was turned OFF
2. The current battery voltage compared to the last battery voltage recorded when the ignition switch was turned OFF
3. The length of time since the last battery temperature calculation

If the calculated battery temperature is below -15°C (+5°F), the PMM institutes steps to control the load.

The BCM calculates the voltage of the battery by making constant voltage measurements and using the measurements to calculate the true battery voltage. If the BCM detects a low voltage, the BCM institutes steps to control the load.

The BCM calculates the net charge rate on the electrical system by making constant voltage measurements and using the measurements to calculate the charge rate in amp/hours. If the BCM detects a negative charge rate, equal to a discharge from the battery, the PMM institutes steps to control the load.

The BCM will either request an increase in the engine idle speed from the ECM or the BCM will turn off loads, called the load-shed function, in order to preserve the vehicle electrical system operation. The criteria used by the BCM to regulate this electrical load management are outlined below

Load Shed System Description and Operation

Each load management function, either idle boost or load-shed, is discrete. No two functions are implemented at the same time.

During each load management function, the BCM checks the battery temperature, battery voltage and amp-hour calculations and determines if the BCM should implement a different power management function.

The highest loads on the electrical system are the resistance load of heating elements. The BCM controls the heating elements in the outside rear view mirrors, the rear window and the heated seats, either directly or by sending messages to any module controlling power to these devices.

The second highest load on the electrical system are the blowers used in the HVAC system. The BCM will send messages to the HVAC system controller that will result in reducing the blower operation on vehicles equipped with automatic HVAC systems.

Idle Boost Functions

The BCM sends a serial data request to the ECM to increase the idle speed. The ECM then adjusts the idle speed by using a special program and idle speed ramp calculations in order to prevent driveability and safety concerns. The idle speed boost and cancel function will vary from vehicle to vehicle and from one moment to another on the same vehicle. This happens because the ECM responds to changes in the inputs from the sensors used to control the powertrain.

Load Shed System Description and Operation

Special Tools

Special Tools Illustration Tool Number/Description J 38758 Parasitic Draw Test Switch J 42000 Battery Tester

Scheme 10

Scheme 11

See also:
• Diagnostic System Check - Vehicle
• Body Control System Schematics
• DTC Symptom Description
• Circuit Testing
• Wiring Repairs
• Testing for Intermittent Conditions and Poor Connections
• Connector Repairs
• Control Module References
• Diagnostic Trouble Code (DTC) List - Vehicle
• Power Distribution Schematics
• Master Electrical Component List
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Cruise Control Schematics
• Diagnostic Repair Verification
• Engine Controls Schematics
• Engine Controls Schematics
• Power and Grounding Connector End Views
• Checking Aftermarket Accessories
• Fastener Notice
• Keyless Entry System Description and Operation
• Battery Disconnect Caution
• Drive Belt Replacement
• Water Pump and Generator Belt Replacement
• Drive Belt Tensioner Diagnosis
• Drive Belt Tensioner Diagnosis
• Engine Will Not Crank - Crankshaft Will Not Rotate
• Engine Will Not Crank - Crankshaft Will Not Rotate
• Engine Flywheel Replacement
• Engine Flywheel Replacement
• Radio/Audio System Description and Operation
• Power Window Reinitialization
• Cooling System Draining and Filling (Static Fill)
• Cooling System Draining and Filling (GE 47716)
• Front Suspension Crossmember Replacement
• DTC B1325
• Charging System Test
• Starter Solenoid Does Not Click
• Scan Tool Data List
• Starting System Description and Operation
• Battery Common Causes of Malfunction
• Charge Indicator Always On
• Charge Indicator Inoperative
• Starter Solenoid Clicks, Engine Does Not Crank
• Engine Cranks Slowly
• Special Tools
• Battery Usage