Battery, Charging System and Starting System GMC Sierra 2500

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Engine running, accessories OFF, measure and record the battery voltage at the battery terminals. The voltage should be between 12 and 15 V. If the battery voltage is not within the specified range, refer to «Battery Inspection/Test»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Observe the appropriate module scan tool Battery Voltage parameters. Verify that the scan tool displays a value that is within 2 V of the battery terminal voltage.

Circuit/System Testing

Note. Use the schematic to identify the following: Control modules the vehicle is equipped with The control modules ground, B+, and Ignition circuit terminal IDs and connectors

Ignition OFF, disconnect the harness connectors at the appropriate control module.
Ignition OFF, scan tool disconnected, open and close the driver door and wait 1 minute. Test for less than 10 ohms between each ground circuit terminal and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
If equipped, verify that a test lamp illuminates between each B+ circuit terminal and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
If equipped, ignition ON, verify that a test lamp illuminates between each ignition circuit terminal and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
If all circuits test normal, replace the control module module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for control module replacement, programming and setup

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
BCM B+	B1516 08	B1516 08
5-Volt Reference	B1516 08	B1516 08
Signal	B1516 08	B1516 08	B1516 08	B1516 08, B1516 66
Low Reference		B1516 08

Typical Scan Tool Data

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Ignition ON, engine OFF. Headlamps and all accessories Off. Parameter Normal Range: -5A to -25A
BCM B+	59.9A	59.9A
5-Volt Reference	59.9A	59.9A
Signal	59.9A	59.9A	59.9A
Low Reference		59.9A

Battery Current - BCM

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Ignition ON, engine OFF. Parameter Normal Value: 12.60V
BCM B+	25.60V	26.10V

Battery Voltage - BCM

The battery current sensor is a 3-wire hall effect current sensor. The battery current sensor monitors the battery current. The signal circuit is an input to the body control module (BCM). The sensor creates a 5-volt pulse width modulation (PWM) signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty cycle is between 4-96 percent. The signal circuit is an input to the body control module (BCM). If the duty cycle is outside of the normal range, DTC B1516 08 sets. The BCM also tests for correct polarity of the sensor. If the BCM detects positive current flow with the engine OFF, DTC B1516 66 sets.

B1516 08

The BCM is awake.

B1516 66

The BCM is awake.
The engine is OFF.
The hood and doors are closed.
DTC B1516 08 has run and passed during this ignition cycle.
DTC B1516 66 has not already run and passed during this ignition cycle.

B1516 08

The BCM detects the sensor signal duty cycle is less than 4 percent or greater than 96 percent for 2 minutes.

B1516 66

The BCM detects positive battery current when the engine is OFF.

Regulated voltage control (RVC) is disabled.

The DTC passes when the battery sensed current returns to the normal range for 15 seconds.
A history DTC will clear after 100 ignition cycles.

Schematic Reference

«Starting and Charging Schematics»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Body Control System Schematics»(/gmc/sierra-2500/2012-2012/remont/communication-devices/#data-communications-system)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, headlamps and all accessories OFF, observe the scan tool BCM Battery Current parameter. The reading should be between -5 amps and -25 amps, and change with the amount of current draw on the battery.

Ignition ON, observe the scan tool BCM Battery Voltage parameter. The reading should be equal to B+ voltage. If not the specified value, test the following BCM circuits for an open/high resistance. If the circuits test normal, replace the BCM. B+ circuit terminal 3 X3 Ground circuit terminal 1 X3 Ground circuit terminal 5 X3 Ground circuit terminal 9 X4
Verify that the current sensor is mounted correctly on the negative battery cables. The sensor should be installed with the internal coil around the negative battery cables, with the tape tab pointing away from the battery. If the sensor is not installed correctly, remove and reinstall the sensor.
Ignition OFF, disconnect the harness connector at the battery current sensor.
Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 ohms between the low reference circuit terminal B and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
Ignition ON, test for 4.5-5.5 volts between the 5-volt reference circuit terminal A and ground. If not within the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
Ignition ON, test for 4.5-5.5 volts between the signal circuit terminal C and ground. If not within the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
If all circuits test normal, replace the battery current sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Battery Current Sensor Replacement»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Control Module References»(/gmc/sierra-2500/2012-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The body control module (BCM) monitors the battery voltage level during an engine crank event to detect a low battery voltage condition.

The vehicle is ON

A minimum crank battery voltage is less than the minimum crank battery voltage threshold for 16 consecutive crank events.

A driver information center (DIC) message is displayed.

The DTC will clear if the minimum crank voltage is greater than the minimum crank voltage threshold during a crank event.

Schematic Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Connector End View Reference

Description and Operation

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Before replacing the C1 battery perform the Battery Inspection/Test .

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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.

The ignition must be in Accessory or Run mode for this code to set.

The state of charge at ignition ON is 30 percent lower than when the engine was running and battery drain is more than 2 A.

There is no battery telltale illuminated or DIC message displayed.

The DTC will clear if the fault does not return after 50 consecutive ignition cycles.
The DTC will clear when run state of charge is greater than or equal to 80 percent.

Schematic Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Connector End View Reference

Description and Operation

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Refer to Battery Electrical Drain/Parasitic Load Test .

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Control	P0615	P0615	P0615
Ground		P0615

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 is pressed for the manual transmission or that the automatic transmission is in park or neutral, and that the immobilizer is not disabling engine starting. If conditions are acceptable for cranking, then the ECM supplies 12 V to the control circuit of the STRTR relay. When this occurs, battery voltage is supplied through the switch of the STRTR relay to terminal S X2 of the starter solenoid, and the engine cranks. The ECM monitors the voltage on the STRTR relay control circuit.

The ignition is ON.
The battery voltage is 9.5-18 V.

The control circuit of the STRTR relay is open or shorted to voltage for 2 seconds when the ignition switch is in the ON position.
The control circuit of the STRTR relay is shorted to ground for 5 seconds when the ignition switch is in the start position.

DTC P0615 is a type C DTC.

The DTC passes when the ECM detects that the failure is no longer present for 2 seconds.

If this DTC sets due to a short to ground, the engine may crank but not start, until the ignition is cycled OFF and then ON again.
A short to ground on the control circuit may damage the ECM.

Schematic Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Connector End View Reference

Description and Operation

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition OFF, disconnect the STRTR relay.
Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 ohms between the relay ground circuit terminal 85 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85. Turn the ignition to the start position. The test lamp should turn ON when the ignition is in the START position, and OFF in all other positions. If the test lamp is always on, test the control circuit for short to voltage. If the circuit tests normal, replace the ECM. If the test lamp is always off, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
If all circuits test normal, test or replace the STRTR relay.

Component Testing

Relay Test

Ignition OFF, disconnect the STRTR relay.
Test for 60-180 ohms between terminals 85 and 86. If not within the specified range, replace the relay.
Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified value, replace the relay.
Install a 20 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Relay Replacement (Within an Electrical Center)»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions__relay-replacement-within-an-electrical-center) , «Relay Replacement (Attached to Wire Harness)»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
«Control Module References»(/gmc/sierra-2500/2012-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming.

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Control	P0615	P0615
Ground		P0615

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 is pressed for the manual transmission or that the automatic transmission is in Park or Neutral, and that the immobilizer is not disabling engine starting. If conditions are acceptable for cranking, then the ECM supplies 12 V to the control circuit of the STRTR relay. When this occurs, battery voltage is supplied through the switch of the STRTR relay to the starter solenoid, and the starter cranks. The ECM monitors the voltage on the STRTR relay control circuit.

The ignition switch is in the RUN position.
The battery voltage is 9.5-18 V.

The control circuit of the STRTR relay is open or shorted to ground for 2 seconds.

DTC P0615 is a type C DTC.

The DTC passes when the ECM detects that the failure is no longer present, and the engine cranks.

Schematic Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Connector End View Reference

Description and Operation

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition OFF, disconnect the STRTR relay.
Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 ohms between the relay ground circuit terminal 85 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85. Turn the ignition to the start position. The test lamp should turn ON when the ignition is in the START position, and OFF in all other positions. If the test lamp is always on, test the control circuit for short to voltage. If the circuit tests normal, replace the ECM. If the test lamp is always off, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
If all circuits test normal, test or replace the STRTR relay.

Relay Test

Ignition OFF, disconnect the STRTR relay.
Test for 60-180 ohms between terminals 85 and 86. If not within the specified range, replace the relay.
Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified value, replace the relay.
Install a 20 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Relay Replacement (Within an Electrical Center)»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions__relay-replacement-within-an-electrical-center) , «Relay Replacement (Attached to Wire Harness)»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
«Control Module References»(/gmc/sierra-2500/2012-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming.

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage
B+	P0622	P0622
Signal	P0622	P0622
Control	P0621		P0621

The engine control module (ECM) uses the charge indicator signal 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 signals the voltage regulator to turn the field circuit ON and OFF. The ECM monitors the state of the charge indicator signal circuit.

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

The charge indicator signal circuit is shorted to ground or shorted to voltage for 15 seconds.

The charge indicator turns ON.
The driver information center (DIC) displays the SERVICE BATTERY CHARGING SYSTEM message.

The DTC will pass when the condition for setting the DTC is no longer present for 1 second.
A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
The charge indicator and DIC message will remain ON until the DTC passes or is cleared, even if the ignition is cycled.

A scan tool can be used to command the GEN L-Terminal circuit ON to 85% and OFF to 14% while the engine is running. Typical voltage values for the charge indicator control circuit are 4.3 V at 85% and 0.85 V at 14%.

Schematic Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Connector End View Reference

Description and Operation

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

4.3L Engine

Verify that a test lamp illuminates between the G13 generator B+ terminal 1 X2 and ground. If the test lamp does not illuminate and the circuit fuse is good Ignition OFF. Test for less than 2 ohms in the B+ circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF. Test for greater than 100 ohms between the B+ circuit and ground. If 100 ohms or less, repair the short to ground on the circuit. If greater than 100 ohms, replace the generator. If the test lamp illuminates
Ignition OFF, disconnect the X1 harness connector at the generator, ignition ON.
Test for less than 1 V between the generator turn on signal circuit terminal 1 and ground. If 1 V or greater Ignition OFF, disconnect the harness connector at the ECM, ignition ON. Test for less than 1 V between the signal circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the ECM. If less than 1 V
Engine running.
Test for greater than 3.5 V between the generator turn on signal circuit terminal 1 and ground. If 3.5 V or less Ignition OFF, disconnect the harness connectors at the ECM. Test for infinite resistance between the signal circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the signal circuit end to end. If greater than 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, replace the ECM. If greater than 3.5 V
Test or replace the generator.

4.8L, 5.3L, 6.0L, 6.2L, or 7.0L Engine

Verify that a test lamp illuminates between the G13 generator B+ terminal 1 X2 and ground. If the test lamp does not illuminate and the circuit fuse is good Ignition OFF. Test for less than 2 ohms in the B+ circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF. Test for greater than 100 ohms between the B+ circuit and ground. If 100 ohms or less, repair the short to ground on the circuit. If greater than 100 ohms, replace the generator. If the test lamp illuminates
Ignition OFF, disconnect the X1 harness connector at the generator, ignition ON.
Test for 4.5-5.5 V between the control circuit terminal 1 and ground. If less than 4.5 V Ignition OFF, disconnect the harness connectors at the ECM. Test for infinite resistance between the control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the signal circuit end to end. If greater than 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, replace the ECM. If greater than 5.5 V Ignition OFF, disconnect the harness connectors at the ECM, ignition ON. Test less than 1 V between the control circuit and ground. If greater than 1 V, repair the short to voltage on the circuit. If less than 1 V, replace the ECM. If between 4.5-5.5 V
Test or replace the generator.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Control Module References»(/gmc/sierra-2500/2012-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming.

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Field Duty Cycle Signal	P0622	P0622
Charge Indicator Signal			P0621

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

The charge indicator signal circuit is shorted to ground or shorted to voltage for 20 seconds.

The charge indicator turns ON.
The driver information center (DIC) displays the SERVICE BATTERY CHARGING SYSTEM message.

The DTC will pass when the condition for setting the DTC is no longer present for 2 seconds.
A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
The charge indicator and DIC message will remain ON until the DTC passes or is cleared, even if the ignition is cycled.

A scan tool can be used to command the GEN L-Terminal circuit ON to 84% and OFF to 14% while the engine is running. Typical voltage values for the charge indicator control circuit are 4.1 V at 85% and 0.78 V at 14%.

Schematic Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Connector End View Reference

Description and Operation

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing - Single Generator (w/o K76)

Verify that a test lamp illuminates between the generator B+ terminal 1 X2 and ground. If the test lamp does not illuminate and the circuit fuse is good Ignition OFF. Test for less than 2 ohms in the B+ circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF. Test for greater than 100 ohms between the B+ circuit and ground. If 100 ohms or less, repair the short to ground on the circuit. If greater than 100 ohms, replace the generator. If the test lamp illuminates
Ignition OFF, disconnect the X1 harness connector at the generator, ignition ON.
Test for 3.5V or greater between the control circuit terminal 1 X1 and ground. If less than 3.5V Ignition OFF, disconnect the harness connectors at the ECM. Test for infinite resistance between the control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the control circuit end to end. If greater the 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, replace the ECM. If 3.5V or greater Ignition OFF, disconnect the harness connectors at the ECM. Test for less than 1 V between the control circuit and ground. If less than 1 V, replace the G13 Generator. If 1 V or greater, repair the short to voltage on the circuit.

Circuit/System Testing - Dual Generators (K76)

Verify that a test lamp illuminates between the each generator B+ terminal A X2 and ground. If the test lamp does not illuminate and the circuit fuse is good Ignition OFF. Test for less than 2 ohms in each B+ circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF. Test for greater than 100 ohms between the B+ circuit and ground. If 100 ohms or less, repair the short to ground on the circuit. If greater than 100 ohms, replace theappropriate generator. If the test lamp illuminates
Ignition OFF, disconnect the X1 harness connectors at both generators, ignition ON.
Test for 3.5V or greater between the control circuit terminal 1 X1 and ground. If less than 3.5V Ignition OFF, disconnect the harness connectors at the ECM. Test for infinite resistance between the control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the control circuit end to end. If greater the 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, replace the ECM. If 3.5V or greater Ignition OFF, disconnect the harness connectors at the ECM. Test for less than 1 V between the control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V Ignition OFF, connect X1 harness connector at the auxiliary generator, Ignition ON. Test for less than 1 V between the control circuit and ground. If greater than 1 V, replace the auxiliary generator. If less than 1 V Engine running, test for 3.5 V or greater between signal circuit terminal 1 and ground. If less than 3.5 V, test or replace the auxiliary generator. If 3.5 V or greater, test or replace the generator

Perform the Diagnostic Repair Verification after completing the repair.

«Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Control Module References»(/gmc/sierra-2500/2012-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, programming, and setup.

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage
B+	P0622	P0622
Field Duty Cycle Signal	P0622	P0622
Charge Indicator Signal	P0621		P0621

Circuit	Short to ground	Open	Short to voltage
Operating Conditions: Engine Running Parameter Normal Range: 5% to 99%
B+	0%	0%
Field Duty Cycle Signal	0%	0%	99%

GEN F-Terminal Signal - ECM

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 percent. When the engine is running, the duty cycle should be between 5-99 percent.

The engine is running.
The battery voltage is 9.5-18 V.

The GEN F-Terminal Signal is less than 5 percent for 30 seconds.

The charge indicator turns ON.
The driver information center (DIC) displays the SERVICE BATTERY CHARGING SYSTEM message.

The DTC will pass when the condition for setting the DTC is no longer present.
A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
The charge indicator and DIC message will remain ON until the DTC passes or is cleared, even if the ignition is cycled.

Schematic Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Connector End View Reference

Description and Operation

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, engine OFF, observe the scan tool ECM GEN-F Terminal Signal parameter. The parameter should read 0%.
Engine running, observe the scan tool ECM GEN-F Terminal Signal parameter. The parameter should read between 5 and 99%.

Verify that a test lamp illuminates between the B+ circuit terminal 1 X2 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
Ignition OFF, disconnect the X1 harness connector at the generator.
Ignition ON, verify the scan tool ECM GEN-F Terminal Signal parameter is 0%. If greater than the specified value, test the field duty cycle circuit terminal 2 X1 for a short to voltage. If the circuit tests normal, replace the ECM.
Connect a test lamp between the field duty cycle circuit terminal 2 X1 and B+. Verify the scan tool ECM GEN-F Terminal Signal parameter is greater than 95%. If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
If all circuits test normal, test or replace the generator.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Control Module References»(/gmc/sierra-2500/2012-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming.

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Field Duty Cycle Signal	P0622	P0622
Charge Indicator Signal			P0621

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine running. Parameter Normal Range: 5 - 100%
Field Duty Cycle Signal	0%	0%	100%

GEN-F Terminal Signal - ECM

The ignition is ON.
The engine is running.
The battery voltage is 9.5-18 V.

The GEN F-Terminal Signal is greater than 65 percent for 20 seconds.

The charge indicator turns ON.
The driver information center (DIC) displays the SERVICE BATTERY CHARGING SYSTEM message.

The DTC will pass when the condition for setting the DTC is no longer present for 5 seconds.
A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
The charge indicator and DIC message will remain ON until the DTC passes or is cleared, even if the ignition is cycled.

Schematic Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Connector End View Reference

Description and Operation

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, engine OFF, observe the scan tool ECM GEN-F Terminal Signal parameter. The parameter should read 0%.
Engine running, observe the scan tool ECM GEN-F Terminal Signal parameter. The parameter should read between 5 and 100%.

Ignition OFF, disconnect the X1 harness connector at the generator.
Ignition ON, verify the scan tool ECM GEN-F Terminal Signal parameter is 0%. If greater than the specified value, test the field duty cycle circuit terminal 2 for a short to voltage. If the circuit tests normal, replace the ECM.
Connect a test lamp between the field duty cycle circuit terminal 2 and B+. Verify the scan tool ECM GEN-F Terminal Signal parameter is greater than 95%. If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
If all circuits test normal, test or replace the generator.

Perform the Diagnostic Repair Verification after completing the repair.

«Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Control Module References»(/gmc/sierra-2500/2012-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, programming, and setup.

Symptoms - Engine Electrical

Note. The following steps must be completed before using the symptom tables.

Perform «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) 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.
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»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system__battery-description-and-operation) «Charging System Description and Operation»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) «Electrical Power Management Description and Operation (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system__electrical-power-management-description-and-operation) , «Electrical Power Management Description and Operation (Gasoline)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system__electrical-power-management-description-and-operation) «Starting System Description and Operation»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system__starting-system-description-and-operation)

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the starting and charging systems. Refer to «Checking Aftermarket Accessories»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__checking-aftermarket-accessories) .
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

«Battery Inspection/Test»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Battery Electrical Drain/Parasitic Load Test»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Charging System Test»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Generator Noise Diagnosis»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Starter Solenoid Does Not Click»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Starter Solenoid Clicks, Engine Does Not Crank»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Engine Cranks Slowly»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Starter Noise Diagnosis»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

WARNING

Note. The battery test using the regionally available battery tester requires correct connections to the battery terminals. Ensure that battery tester clamps are connected directly to either the battery post or the battery cable terminal. Do not connect clamps to battery cable fasteners. Failure to obtain the correct connections during the test may result in a failed test on a good battery. Use the Out of Vehicle test for each battery when testing a vehicle with dual batteries.

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

If testing the vehicle with the battery cables still connected, wiggle the battery tester clips on the terminal. This may cut through any coating or through any oxidation that may be present on the terminal.
If correct connections to the battery terminals in the vehicle are in doubt, perform the following steps: Disconnect the negative battery cable. Disconnect the positive battery cable. Follow the instructions for testing a removed battery.
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. NOTE: Always write the test code displayed by the tester on the repair order for any warranty purposes. The number is a unique code that describes the test data for a particular battery at a particular time. The test code may occasionally repeat when you retest the same battery. More often, each test will result in a different code. Use the test code from the second, or Out of Vehicle test. Follow the instructions for testing a removed battery. Replace the battery only if the second test shows a REPLACE BATTERY or BAD CELL-REPLACE result. Use the test code from the second test for any warranty purposes.

Schematic Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Connector End View Reference

Description and Operation

Control Module References

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

Battery Tester, for regionally available devices, refer to Special Tools .

WARNING

Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components. For Vehicles equipped with OnStar® (UE1) with Back Up Battery: The Back Up Battery is a redundant power supply to allow limited OnStar® functionality in the event of a main vehicle battery power disruption to the VCIM (OnStar®module). Do not disconnect the main vehicle battery or remove the OnStar® fuse with the ignition key in any position other than OFF. Retained accessory power (RAP) should be allowed to time out or be disabled (simply opening the driver door should disable RAP) before disconnecting power. Disconnecting power to the OnStar® module in any way while the ignition is On or with RAP activated may cause activation of the OnStar® Back-Up Battery (BUB) system and will discharge and permanently damage the back-up battery. Once the Back-Up Battery is activated it will stay on until it has completely discharged. The BUB is not rechargeable and once activated the BUB must be replaced.

Verify the C1 battery case is not cracked, broken, or damaged, which may be indicated by battery acid leakage. If there is any apparent damage Replace the C1 battery. If there is no damage
Verify the cold cranking amperage and amperage hour rating of the C1 battery. Refer to the manufacturer specifications on the battery label. If the C1 battery does not meet or exceed specifications Replace the C1 Battery. If the C1 Battery meets or exceeds specifications
Verify that the battery cables are clean and tight. The battery terminal bolts should be torqued as specified in «Fastener Tightening Specifications»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system__fastener-tightening-specifications) . If the battery cables need to be cleaned or tightened Clean as required and tighten as specified. If the battery cables are clean and tight
Install the battery tester and follow directions supplied by the tester.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Battery Replacement

Special Tools

EL 42000 Battery Tester

For equivalent regional tools, refer to Special Tools .

For best results, use an automatic taper-rate battery charger with a voltage capability of 16 V.
The charging area should be well ventilated.
Do not charge a battery that appears to be frozen. Allow the battery to warm to room temperature and test it using the EL 42000 before charging.

Battery State of Charge

Note. Using voltage to determine the batteries state of charge is only accurate after the battery has been at rest for 24 hours. This is enough time for the acid in each cell to equalize. If the battery has been charged or discharged in the past 24 hours, the battery state of charge will only be an estimate.

The maintenance-free batteries state of charge is estimated by reading the voltage of the battery across the battery terminals. Because the voltage is affected by current flow into or out of the battery, the engine must be stopped and all electrical loads turned OFF, including parasitic loads, when checking the voltage. The voltage can also be affected if the battery has just been charged or discharged, so it is important to consider what has happened to the battery in the time just before testing. Use the following procedure to determine the batteries state of charge

Be sure all electrical loads are turned OFF.
Determine whether the battery has been used in a vehicle or charged within the past 12 hours. If the answer is no, the terminal voltage will be stabilized and no action is necessary before reading the voltage. Skip to step 3. If the answer is yes, terminal voltage will not be stabilized and you should wait 12 hours since the last time the battery was used.
Estimate the battery temperature by determining the average temperature to which the battery has been exposed for the past 12 hours.
Measure the battery voltage at the battery terminals. Refer to the following table to determine the state of charge according to the estimated battery temperature

Battery Voltage	% Charge at 0°C (32°F)	% Charge at 25°C (75°F)
12.75 V	100%	100%
12.7 V	100%	90%
12.6 V	90%	75%
12.45 V	75%	65%
12.2 V	65%	45%
12.0 V	40%	20%

Use the state of charge information as follows

A battery with a state of charge that is below 65 percent must always be recharged before returning it to service or continuing storage.
A battery with a state of charge that is 65 percent or greater is generally considered to be charged enough in order to be returned to normal service or in order to continue storage. However, if the battery is being used in slow traffic or with short drive times, or if the temperature is very hot or very cold, the battery should be fully charged, to at least 90 percent, before returning it to service or continuing storage.

Charging Time Required

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

The battery charger capacity-The higher the charger amperage, the less time it will take to charge the battery.
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 V, 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 manufacturer's instructions for operating this circuitry.
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

CAUTION

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 ECM/PCM or other electronic components.

CAUTION

Refer to Fastener Caution .

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 Y (11 lb ft).

Use the following procedure to charge the battery

Turn OFF the charger.
Ensure that all of the battery terminal connections are clean and tight.
Connect the charger positive lead to the battery positive terminal on the battery or the remote jumper stud underhood.
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.
Turn ON the charger and set to the highest setting for normal charging.
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.
After charging, test the battery. Refer to «Battery Inspection/Test»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

12 V Battery

The following procedure is for the 12 V battery only.

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Components most likely to cause a parasitic draw on the vehicles 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 min 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.

Rule out any possible aftermarket equipment causing an unacceptable parasitic current drain. Aftermarket accessories installed into the courtesy lamp circuit can cause the inadvertent power timer in the body control module (BCM) to keep resetting. This may cause the BCM to remain awake and cause a current drain on the battery.
Rule out customer driving habits such as regular short trips that do not allow enough time to properly charge the battery. Refer to «Battery Description and Operation»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system__battery-description-and-operation) .
Verify that the battery and charging system are in proper working order. Refer to «Battery Charging»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , and «Charging System Test»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
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.
Some systems and modules such as OnStar®, and regulated voltage control, 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»(/gmc/sierra-2500/2012-2012/remont/communication-devices/#data-communications-system__body-control-system-description-and-operation) for the system or modules description and operation.
An engine off natural vacuum evaporative test can occur if the engine control module (ECM) determines the drive cycle has met the appropriate criteria immediately after key off. The ECM will stay awake and the vent solenoid will stay energized for as long as 45 min. The typical current draw for this is about 1 A.
Digital OnStar generator 6 and later vehicle communication interface module do not "wake up" every 10 min for the first 48 h as the generator 5 and prior. Generator 6 and later vehicle communication interface module current draw is very low, less than 40 mA, so the OnStar system is left in that state for up to the first 48 h. Parasitic draw of up to 40 mA with an occasional spike as high as 80 mA through the vehicle communication interface module for the first 48 h is normal.
Some automatic climate control systems can remain in a semi awake state for up to three hours, actual draw amounts vary by vehicle platform but are typically not greater than 50 mA.
An extremely low mA current level is consumed by the remote keyless entry receiver for monitoring purposes, actual system wake up only occurs when the fobs for the vehicle are used. When other devices on the same remote keyless entry operating frequency are activated, such as the 4 tire pressure monitoring sensors and other vehicle FOBs in the vicinity, the remote keyless entry receiver will have a 100 mA spike. These spikes are normal and occur too briefly to have a significant effect on battery drain. Competing signals may cause remote keyless entry performance issues such as jamming but should not cause excessive battery draw.
If an excessive current draw is not present during initial testing, continue periodic testing over a 1-2 hour period to see if the current draw increases and stays above an unacceptable level.
The battery run down time will vary depending on the batteries reserve capacity. If the reserve capacity is higher, then the battery run down time may be longer. If the reserve capacity is lower, then the battery run down time may be shorter. The graph below indicates roughly how many days a 690 cold cranking amperage battery with a 110 min. reserve capacity 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 reserve capacity and temperature will affect the results.

Current Drain	Days
25 mA	33
50 mA	16.5
75 mA	11
100 mA	8.25
250 mA	3.3
500 mA	1.65
750 mA	1
1 A	0.8
2 A	0.4

Schematic Reference

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL 38758 Parasitic Draw Test Switch

For equivalent regional tools, refer to Special Tools .

Note. Most vehicle systems will go to sleep within 30 min but it can take up to 2 h before all systems power down allowing the parasitic draw test to pass. An occasional increase in the parasitic draw is normal as long as it returns within 1 s. Closing the door latches/ajar switch while leaving the doors open is recommended, this allows the vehicle systems to perform in a "doors closed" mode while allowing vehicle interior access that may be needed to complete the diagnostic steps. Locking doors will arm the vehicle content theft deterrent system if equipped. Failure to arm the system may cause a theft system fault to not be present during testing. There are many things that can prevent the vehicle from completely going to sleep and passing the parasitic draw test. Make sure all the conditions listed below are met before performing the parasitic current draw test. Ignition OFF Key out of the ignition switch - when not equipped with keyless access and start Retained Accessory Power OFF - open and close the driver door after ignition OFF Scan tool not communicating with a vehicle control module - in some cases it may need to be disconnected from the DLC All access doors closed Headlamps OFF - auto headlamps disabled Any delay lighting OFF If equipped with an under hood lamp disable it HVAC after blow OFF Any accessory that can work with ignition OFF inactive or OFF Wait up to 2 min or longer, after all other listed conditions are met

Using an Inductive Pickup Probe

Connect an inductive pickup probe to the negative battery cable that can read down to 1 mA.
Ignition OFF, as the vehicle systems shut down test for less than 30 mA of parasitic current drain. If greater than the specified range, refer to Circuit/System Testing below.

Using the EL 38758 Parasitic Draw Test Switch

Ignition OFF, disconnect the battery negative cable from the battery. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Turn the EL 38758 switch knob to the OFF position.
Install the male end of the EL 38758 switch to the battery ground terminal.
Install the battery negative cable to the female end of the EL 38758 switch.
Turn the EL 38758 switch knob to the ON position.
Road test the vehicle and activate all of the accessories such as the radio and air conditioning.
Ignition OFF, connect a 10 A fused jumper wire to the test switch tool terminals.
Turn the EL 38758 switch knob to the OFF position. The current now flows through the jumper wire.
Check the fuse in the jumper wire. The fuse should be OK. Failed: If the jumper wire fuse is blown, refer to Circuit/System Testing below. Passed
Turn the EL 38758 switch knob to the ON position. Remove the fused jumper wire.
Connect a DMM set to the 10 A DC scale between the test switch tool terminals.
Turn the EL 38758 switch knob to the OFF position. The current now flows through the DMM.
As the vehicle systems shut down test for less than 30 mA of parasitic current drain. If greater than the specified range, refer to Circuit/System Testing below.

Note. Removing or installing a fuse, relay, or connector, to determine the area causing high parasitic draw may wake up control modules. You must wait for the control modules to go back to sleep before retesting. It is best to install any removed or disconnected components after the diagnosis is completed. Fuses for power mode master components such as the BCM should be removed last to avoid misdiagnosis. If a scan tool is connected to the DLC, either disconnect it or subtract the scan tool current draw from the DMM reading to get the actual vehicle parasitic current draw.

If the vehicle has an unacceptable amount of parasitic current draw, remove each fuse one at a time until the current draw falls to an acceptable level. A drop of more than 10-20 mA, when disabling a single system or circuit, is an indication of an overly high current draw that could be causing the battery drain. Refer to Power Distribution Schematics to diagnose exactly which circuit of the suspect system is causing the high parasitic drain. The following is a list of common components that could cause a high current draw

Stuck switch
Stuck relay
Control module

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for control module replacement, programming and setup

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

A vehicle accessory was left on overnight.
The driving speeds have been slow with frequent stops with many electrical accessories in use, particularly air conditioning, headlights, wipers, heated rear window, cellular telephone, etc.
The electrical load has exceeded the generator output, particularly with the addition of aftermarket equipment.
Existing conditions in the charging system, including the following possibilities: A slipping belt A bad generator
The battery has not been properly maintained, including a loose battery hold down or missing battery insulator if used.
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»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures) .

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 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 a battery state of charge while storing the vehicle for more than 30 days, disconnect the battery ground to protect the battery from discharge by parasitic current drains.

When the battery cannot be disconnected

Maintain a high state of charge.
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.

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Description and Operation

Testing for Intermittent Conditions and Poor Connections

Electrical Information Reference

Ignition ON, verify that no G13 generator or B18 battery current sensor DTCs are set that would cause a charging system concern. If DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
Ignition OFF, measure the voltage across the battery terminals. The voltage should read 12.0 V or greater at room temperature. If not within specified range, refer to «Battery Inspection/Test»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Engine ON, increase engine speed to 2, 500 RPM. Verify the battery voltage is between 12.6-15.0 V. If not within specified range, replace the G13 generator.
Engine ON, increase engine speed to 2, 500 RPM. Turn ON all vehicle accessories. Verify the battery voltage is between 12.6-15.0 V. If not within specified range, replace the G13 generator.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Generator Replacement (Diesel) , Generator Replacement (V6) , Generator Replacement (V8)

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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.

Start the engine. Verify the noise can be heard. Compare the concern to a similar vehicle.
Perform a charging system test. Verify that the generator is charging properly.
Inspect the generator, generator mounting, wiring harness, heater hoses, A/C lines, or other accessory equipment that may be misrouted or be the cause of noise being transmitted into the passenger compartment.
Ignition OFF, remove the engine drive belt. Verify the generator, A/C compressor, water pump pulley, power steering pump, idler pulley, and tensioner pulley spin freely. If any of the pulleys do not spin freely, replace the affected component.
Start the engine, with the drive belt removed. Verify that the noise goes away. Operate the engine for no longer than 30-40 seconds. If the noise is still present, the generator is not the cause of the noise.
Loosen all generator mounting bolts and ensure the generator is properly aligned. Tighten the mounting bolts to specification, refer to «Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Drive Belt Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-43l) for the 4.3L (LU3) engine
«Drive Belt Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) for the 6.6L Diesel (LML) engine
«Drive Belt Replacement - Accessory»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-repair-instructions-on-vehicle) for all other engines (without LU3 or LML)
«Air Conditioning Compressor Belt Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-repair-instructions-on-vehicle) for all other engines (without LU3 or LML)
«Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
B+	1	1
175 A MEGA Fuse		1
STRTR Fuse		1
Park Neutral Signal (Automatic)	2	1	1
Clutch Pedal Position Signal (TZ0 Manual)	P0807	P0807	P0808	P0806
Starter Relay Coil Control	1	1	3
Starter Solenoid Crank Voltage	1	1	3
Underhood Fuse Block Ground		1
1. No crank 2. Cranks in any gear 3. Cranks all the time

The engine control module (ECM) controls engine cranking based on a power mode input and the status of the park/neutral position (PNP) switch or clutch pedal position sensor. With the transmission in Park/Neutral, voltage at the ECM PNP switch signal circuit is low. This indicates to the ECM that conditions are acceptable for cranking. When a power mode crank request is seen, the ECM applies voltage to the starter relay control circuit. This energizes the coil side of the relay, which pulls the switch side of the relay closed, applying voltage to the starter terminal S X2 and engaging the starter solenoid.

Inspect the STRTR Fuse 60 (LMM) or 64 (w/o LMM), and the 175 A MEGA Fuse for an open.
A misadjusted PNP switch (M30 4L60E, M70 4L70E) or range selector lever cable (automatic) may result in a starter solenoid does not click condition.

Schematic Reference

«Starting and Charging Schematics»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Manual Transmission Schematics»(/gmc/sierra-2500/2012-2012/remont/manual-trans/#manual-transmission-tremec-5-speed-tz0)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Electrical Information Reference

«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)

Scan Tool Reference

Control Module References for scan tool information

Automatic Transmission

Ignition ON, observe the scan tool ECM PNP Switch parameter while shifting the transmission through each range. The reading should change between In Gear and Park/Neutral. (automatic only) If not the specified values, refer to PNP Switch Malfunction below.
Ignition ON, command the Starter Relay ON and OFF with a scan tool, or turn the ignition switch to the START position. The starter solenoid should engage and the engine should crank. If the solenoid does not engage, refer to STRTR Relay Malfunction below. If the solenoid engages but the engine does not crank, refer to «Starter Solenoid Clicks, Engine Does Not Crank»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Manual Transmission

Observe the scan tool ECM CPP Switch parameter. Verify the parameter displays Applied when the clutch is pressed and displays Released when the clutch is released. If not the specified values, refer to Clutch Pedal Position Switch Malfunction below.
With the clutch fully depressed, turn the ignition switch to the START position. The starter solenoid should engage and the engine should crank. If the solenoid engages but the engine does not crank, refer to «Starter Solenoid Clicks, Engine Does Not Crank»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) . If the solenoid does not engage, refer to Starter Relay Circuit Malfunction below.

Clutch Pedal Position Switch Malfunction (Manual Transmission)

Ignition OFF, disconnect the harness connector at the clutch pedal position switch.
Test for less than 30 ohms between the ground circuit terminal C and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
Ignition ON, observe the scan tool ECM CPP Switch parameter. Verify the parameter displays Applied when the clutch is pressed and displays Released when the clutch is released. If the parameter displays Applied all the time, test the signal circuit terminal D for a short to ground. If the parameter displays Released all the time, test the signal circuit terminal D for an open/high resistance.
If all circuits test normal, replace the clutch pedal position engine start switch.

PNP Switch Malfunction (M30 4L60E, M70 4L70E)

Inspect the range selector lever cable for proper adjustment. Refer to «Range Selector Lever Cable Adjustment»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-4l60-e-repair-instructions-on-vehicle__range-selector-lever-cable-adjustment) .
Inspect the park/neutral position switch for proper adjustment. Refer to «Manual Shift Detent Lever with Shaft Position Switch Assembly Replacement»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-4l60-e-repair-instructions-on-vehicle) .
Ignition OFF. Disconnect the harness connector from the park/neutral switch.
Ignition ON. Probe the ground circuit terminal 7 with a test lamp that is connected to B+. Verify that the test lamp illuminates. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
Verify that the scan tool PNP Switch parameter is In Gear. If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the ECM.
Install a 3 A fused jumper wire between the ground circuit terminal 7 and the signal circuit terminal 3. Verify that the scan tool PNP Switch parameter is Park/Neutral. If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
If all circuits test normal, test or replace the park/neutral position switch.

PNP Switch Malfunction (MYC 6L80E, MYD 6L90E)

Inspect the range selector lever cable for proper adjustment. Refer to «Range Selector Lever Cable Adjustment»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-6l806l90-repair-instructions-on-vehicle__range-selector-lever-cable-adjustment) .
Ignition OFF. Disconnect the 16-way harness connector from the transmission.
Ignition ON. Measure voltage on the park/neutral signal circuit terminal 3 with a DMM. Verify that there is greater than 10 V on the park/neutral signal circuit. If less than the specified range, test the circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the ECM.
Ignition OFF, reconnect the 16-way harness connector to the transmission.
Remove the automatic transmission fluid pan. Refer to «Automatic Transmission Fluid, Fluid Pan and/or Filter Replacement»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-6l806l90-repair-instructions-on-vehicle) .
Disconnect the manual shift shaft position switch connector at the control solenoid valve assembly. Refer to «Manual Shift Shaft Position Switch Replacement»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-6l806l90-repair-instructions-on-vehicle) .
Ignition ON, verify that the scan tool PNP Switch parameter displays In Gear. If not the specified value, replace the ECM.
Connect a 3 A fused jumper wire between the park/neutral signal terminal F at the control solenoid valve assembly and ground. The scan tool PNP Switch parameter should display Park/Neutral when the terminal is connected to ground. If not the specified value, replace the ECM.
If all circuits test normal, test or replace the manual shift shaft position switch.

PNP Switch Malfunction (MW7 Allison)

Inspect the range selector lever cable for proper adjustment. Refer to «Range Selector Lever Cable Adjustment»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-allison-repair-instructions-on-vehicle__range-selector-lever-cable-adjustment) .
Ignition OFF. Disconnect the engine chassis harness to transmission internal harness connector X175.
Verify that the scan tool PNP Switch parameter is In Gear. If not the specified value, test the signal circuit terminal R for a short to ground. If the circuit tests normal, replace the ECM.
Install a 3 A fused jumper wire between the signal circuit terminal R and ground. Verify that the scan tool PNP Switch parameter is Park/Neutral. If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
If all circuits test normal, test or replace the transmission internal mode switch.

STRTR Relay Malfunction

Ignition OFF, disconnect the STRTR relay.
Ignition ON, transmission in Park/Neutral. Verify that a test lamp illuminates between the relay coil ground circuit terminal and B+. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
Probe the STRTR Relay switch B+ circuit terminal with a test lamp that is connected to ground. Verify that the test lamp illuminates. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. Inspect the 175 A MEGA fuse for an open. If the circuit tests normal and the 175 A MEGA fuse is open, test the relay controlled output circuit for a short to ground.
Connect a test lamp between the relay coil ground circuit terminal and the relay coil control circuit terminal.
Ignition ON, transmission in Park/Neutral. Command the Starter Relay ON and OFF with a scan tool, or turn the ignition switch between the START and RUN positions. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the relay coil control circuit for a short to voltage. If the circuit tests normal, replace the ECM. If the test lamp is always OFF, test the relay coil control circuit for a short to ground or and open/high resistance. Inspect the STRTR fuse for an open. If the STRTR fuse is open, test the relay controlled output circuit for a short to ground, or replace the starter solenoid (LMM) or starter. If the circuit and fuse test normal, replace the ECM.
Connect the STRTR relay.
Install a test lamp between the starter ring terminal S X2 and ground.
Ignition ON, transmission in Park, command the Starter Relay ON with a scan tool, or turn the ignition switch to the START position. The test lamp should illuminate. If the test lamp does not illuminate, test the crank voltage circuit for an open/high resistance. If the circuit tests normal, test or replace the STRTR relay.
If all circuits test normal, test or replace the starter solenoid (LMM 6.6L Diesel), or the starter (all other engines).

PNP Switch Test (M30 4L60E, M70 4L70E)

Inspect the range selector lever cable for proper adjustment. Refer to «Range Selector Lever Cable Adjustment»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-4l60-e-repair-instructions-on-vehicle__range-selector-lever-cable-adjustment) .
Inspect the park/neutral position switch for proper adjustment. Refer to «Manual Shift Detent Lever with Shaft Position Switch Assembly Replacement»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-4l60-e-repair-instructions-on-vehicle) .
Ignition OFF. Disconnect the harness connector from the park/neutral switch.
With the PNP switch in the following positions, test for infinite resistance between the ground terminal 7 and the signal terminal 3. R OD D 2 1 If not the specified value, replace the PNP switch.
With the PNP switch in the following positions, test for less than 2 ohms between the ground terminal 7 and the signal terminal 3. P N If greater than the specified range, replace the PNP switch.

Relay Test

Ignition OFF, disconnect the STRTR relay.
Test for 60-180 ohms between terminals 85 and 86. If not within the specified range, replace the relay.
Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified value, replace the relay.
Install a 20 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Range Selector Lever Cable Adjustment»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-4l60-e-repair-instructions-on-vehicle__range-selector-lever-cable-adjustment) (M30 4L60E, M70 4L70E)
«Range Selector Lever Cable Adjustment»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-6l806l90-repair-instructions-on-vehicle__range-selector-lever-cable-adjustment) (MYC 6L80E, MYD 6L90E)
«Range Selector Lever Cable Adjustment»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-allison-repair-instructions-on-vehicle__range-selector-lever-cable-adjustment) (MW7 Allison)
«Relay Replacement (Within an Electrical Center)»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions__relay-replacement-within-an-electrical-center) , «Relay Replacement (Attached to Wire Harness)»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
«Starter Solenoid Cable Replacement (Gas without TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Starter Solenoid Cable Replacement (Gas with TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Starter Solenoid Cable Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Clutch Pedal Engine Start Switch Replacement»(/gmc/sierra-2500/2012-2012/remont/clutches-manual-hydraulic/#manual-transmission-clutch-system) (TZ0 Manual)
«Manual Shift Detent Lever with Shaft Position Switch Assembly Replacement»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-4l60-e-repair-instructions-on-vehicle) (M30 4L60E, M70 4L70E)
«Control Valve Body Assembly Removal»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-6l806l90-repair-instructions-off-vehicle) for shift shaft position switch replacement (MYC 6L80E, MYD 6L90E)
«Control Valve Body Assembly Disassemble»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-6l806l90-repair-instructions-off-vehicle) for shift shaft position switch replacement (MYC 6L80E, MYD 6L90E)
«Transmission Internal Mode Switch Replacement»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-allison-repair-instructions-on-vehicle__transmission-internal-mode-switch-replacement) (MW7 Allison)
«Starter Solenoid Switch Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system__starter-solenoid-switch-replacement-diesel) (LMM 6.6L Diesel)
«Starter Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Starter Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Starter Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Control Module References»(/gmc/sierra-2500/2012-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM or ECM replacement, programming and setup

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Schematic Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Connector End View Reference

Description and Operation

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition OFF, measure and record the battery voltage at the terminals. The voltage should be between 12.0-15.0 V. If not within the specified range, refer to «Battery Inspection/Test»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the drive belts. Refer to one of the following: «Drive Belt Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-43l) for the 4.3L (LU3) engine «Drive Belt Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) for the 6.6L Diesel (LML) engine «Drive Belt Replacement - Accessory»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-repair-instructions-on-vehicle) for all other engines (without LU3 or LML) «Air Conditioning Compressor Belt Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-repair-instructions-on-vehicle) for all other engines (without LU3 or LML)
Using the appropriate tools, rotate the crankshaft by hand and verify the crankshaft rotates. If the crankshaft does not rotate, refer to one of the following: «Engine Will Not Crank - Crankshaft Will Not Rotate»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-43l__engine-will-not-crank-crankshaft) for the 4.3L (LU3) engine «Engine Will Not Crank - Crankshaft Will Not Rotate»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-diagnostic-information-and-procedures__engine-will-not-crank-crankshaft) for the 6.6L Diesel (LML) engine «Engine Will Not Crank - Crankshaft Will Not Rotate»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-diagnostic-information-and-procedures__engine-will-not-crank-crankshaft) for all other engines (without LU3 or LML)
Ignition start, verify the engine does not crank. If the engine cranks, inspect the engine and belt drive system for mechanical binding or seized belt-driven accessory.
Verify that a test lamp illuminates between the starter motor B+ terminal B X1 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
Test for less than 0.5 V between the positive battery cable and terminal B X1 at the starter motor as ignition is switched to start position. If greater than the specified value, replace the positive battery cable.
Test for less than 0.5 V between the negative battery cable and the starter motor case as ignition is switched to start position. If greater than the specified value, replace the negative battery cable.
If all circuits test normal, replace the starter motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Starter Solenoid Cable Replacement (Gas without TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Starter Solenoid Cable Replacement (Gas with TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Starter Solenoid Cable Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Battery Negative Cable Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Battery Positive Cable Replacement (Gas)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Positive Cable Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Positive Cable Replacement (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Starter Solenoid Switch Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system__starter-solenoid-switch-replacement-diesel)
«Starter Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Starter Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Starter Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Schematic Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX

Connector End View Reference

Description and Operation

Electrical Information Reference

«Circuit Testing»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition OFF, measure and record the battery voltage at the C1 terminals. The voltage should be between 12.0-15.0 V. If not within the specified range, refer to «Battery Inspection/Test»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the drive belts. Refer to one of the following: «Drive Belt Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-43l) for the 4.3L (LU3) engine «Drive Belt Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) for the 6.6L Diesel (LML) engine «Drive Belt Replacement - Accessory»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-repair-instructions-on-vehicle) for all other engines (without LU3 or LML) «Air Conditioning Compressor Belt Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-repair-instructions-on-vehicle) for all other engines (without LU3 or LML)
Ignition Start, verify the engine does not crank normal. If the engine cranks normal, inspect the engine and belt drive system for mechanical binding, or seized belt-driven accessory.
Verify that a test lamp illuminates between the M64 starter motor B+ terminal A X2 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
Test for less than 0.5 V between the positive battery cable and terminal A X2 at the M64 starter motor as ignition is switched to start position. If greater than the specified value, replace the positive battery cable.
Test for less than 0.5 V between the negative battery cable and the M64 starter motor case as ignition is switched to start position. If greater than the specified value, replace the negative battery cable.
If all circuits test normal, replace the M64 starter motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Battery Positive Cable Replacement (Gas)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Positive Cable Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Positive Cable Replacement (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Battery Negative Cable Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
«Starter Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Starter Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Starter Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)

Perform the «Diagnostic System Check - Vehicle»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The PG starter motors are non-repairable. 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.

Description and Operation

Start the engine. Listen to the starter noise while the engine is cranking. Compare the concern to a similar vehicle.

Remove the flywheel inspection cover.
Inspect the flywheel for the following: Loose flywheel bolts Chipped gear teeth Missing gear teeth Bent flywheel Debris in the bell housing If not within specifications, remove the debris, tighten the flywheel bolts, or repair or replace the flywheel.
If all inspections were within specification, replace the starter motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Fastener Tightening Specifications»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-43l__fastener-tightening-specifications) for the 4.3L (LU3) engine
«Fastener Tightening Specifications»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-specifications__fastener-tightening-specifications) for the 6.6L (LGH, LML) engine
«Fastener Tightening Specifications»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-specifications__fastener-tightening-specifications) for the V8 engines.
«Engine Flywheel Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-43l) for the 4.3L (LU3) engine
«Engine Flywheel Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle__engine-flywheel-replacement) for the 6.6L (LMM) engine
«Engine Flywheel Removal»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-repair-instructions-off-vehicle__engine-flywheel-removal) for the V8 engines.
«Starter Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Starter Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Starter Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)

Disconnect Procedure

Turn off all the lamps and accessories.
Turn the ignition OFF.
Loosen the negative cable nut (1).
Reposition the negative battery cable away from the battery.

Connect Procedure

Position the negative battery cable to the battery.
Install the negative battery cable clamp onto the battery terminal.
Tighten the negative cable clamp nut (1) to 5 N.m (44 lb in).

Turn off all the lamps and accessories.
Turn the ignition OFF.
Loosen the negative battery cable clamp nut (1).
Reposition the negative battery cable.
Loosen the auxiliary negative battery cable clamp nut (1).
Reposition the auxiliary battery negative cable (2) away from the battery.

Install the auxiliary negative battery cable (2) onto the auxiliary battery negative post.
Tighten the negative battery cable nut (1) to 7 N.m (66 lb in).
Install the negative battery clamp onto the battery negative post.
Tighten the negative battery cable clamp nut (1)to 7 N.m (66 lb in).

Removal Procedure

Remove the negative battery cable. Refer to «Battery Negative Cable Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Mark the location of the battery current sensor on the battery cable with tape for reference during installation.
Remove the tape securing the battery current sensor to the negative battery cable.
Mark the location of the negative battery cable clips (1) and remove the clips from the cable.
Squeeze the negative battery cable branches together.
Slide the battery current sensor (2) off of the negative battery cable.

Installation Procedure

Squeeze the negative battery cable branches together.
Slide the NEW battery current sensor (2) up onto the negative battery cable to the location previously marked during removal.
Wrap electrical tape around the battery current sensor leg in order to secure the sensor to the negative battery cable.
Install the negative battery cable clips (1) to the cable to the locations previously marked during removal.
Install the negative battery cable. Refer to «Battery Negative Cable Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the retainers (2) holding the battery negative cable to the battery tray and transmission cooler line.
Remove the engine ground bolt (1) and the frame ground bolt (2).
Disconnect the remaining retainers and remove the battery negative cable (3) from the vehicle.

Install the frame ground bolt (2) and tighten to 25 N.m (18 lb ft).
Install the engine ground bolt (1) and tighten to 25 N.m (18 lb ft).
Connect the battery retainer clips to the harness and the frame bracket.
Connect the battery retainer clips to the battery tray and transmission cooler line.
Install the battery negative post clamp to the battery. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Scheme 5

Scheme 5: Battery Negative Cable Replacement (V8)

Callout	Component Name
Preliminary Procedures Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection (TP2) , Battery Negative Cable Disconnection and Connection (Single Battery) . Remove the oil pan skid plate, if equipped.Refer to Oil Pan Skid Plate Replacement (2500/3500 with RPO NZZ) .
1	Battery Negative Post Clamp Nut CAUTION: Refer to Fastener Caution . Tighten 9 N.m (80 lb in)
2	Engine Block Ground Bolt Tighten 25 N.m (18 lb ft)
3	Frame Ground Bolt Tighten 25 N.m (18 lb ft)
4	Battery Negative Cable Retainer Clips
5	Battery Negative Cable

CAUTION
Refer to Fastener Caution .

Battery Negative Cable Replacement (V8)

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Disconnect the engine wiring harness electrical connector (2) from the battery current sensor.
Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
Remove the oil pan skid plate and bolts, if equipped. Refer to «Oil Pan Skid Plate Replacement (2500/3500 with RPO NZZ)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)
Remove the negative battery cable bolt (2) from the front of the engine block.
Reposition the negative battery cable terminal (1) and the engine wiring harness terminal (3) from the engine block.
Remove the forward lamp wiring harness ground bolt (1).
Remove the forward lamp wiring harness terminal (2) from the frame.
Remove the negative battery cable terminal (3) out through the opening between the radiator support and frame.
Remove the negative battery cable clip (1) from the chassis harness.
Lower the vehicle.
Remove the negative battery cable clip (2) from the right wheelhouse liner.
Remove the negative battery cable from the vehicle.
If replacing the negative battery cable, remove the battery current sensor. Refer to «Battery Current Sensor Replacement»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

If the negative battery cable was replaced, install the battery current sensor. Refer to «Battery Current Sensor Replacement»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Install the negative battery cable to the vehicle.
Install the negative battery cable clip (2) to the right wheelhouse liner.
Raise and support the vehicle.
Install the negative battery cable clip (1) to the chassis harness.
Install the negative battery cable clip (2) to the right wheelhouse liner.
Install the negative battery cable clip (1) to the chassis harness.
Route the negative battery cable terminal (3) through the opening between the radiator support and frame.
Ensure that the negative battery cable is positioned behind the forward lamp harness.
Install the forward lamp wiring harness terminal (2) to the frame. Ensure that the anti-rotation tab is inserted into the hole in the frame.
Install the forward lamp wiring harness ground bolt (1) and tighten to 25 (18 lb ft).
Position the engine wiring harness terminal (3) against the engine block and position the negative battery cable terminal (1) on top of the engine wiring harness terminal.
Install the negative battery cable bolt (2) to the front of the engine block and tighten to 25 (18 lb ft).
If applicable, position the oil pan skid plate and install the bolts and tighten to 28 (21 lb ft).
Lower the vehicle.
Install the battery current sensor clip to the battery tray.
Connect the engine wiring harness electrical connector (2) to the battery current sensor.
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Scheme 6

Scheme 6: Auxiliary Battery Negative Cable Replacement (Diesel)

Callout	Component Name
Preliminary Procedures Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection (TP2) , Battery Negative Cable Disconnection and Connection (Single Battery) .
1	Auxiliary Negative Battery Post Clamp Nut CAUTION: Refer to Fastener Caution . Tighten 9 N.m (80 lb in)
2	Auxiliary Negative Battery Engine Block Ground Bolt Tighten 25 N.m (18 lb ft)
3	Clamp
4	Auxiliary Negative Battery Cable

CAUTION
Refer to Fastener Caution .

Auxiliary Battery Negative Cable Replacement (Diesel)

Scheme 7

Scheme 7: Auxiliary Battery Negative Cable Replacement (TP2)

Callout	Component Name
Preliminary Procedures Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection (TP2) , Battery Negative Cable Disconnection and Connection (Single Battery) .
1	Auxiliary Negative Battery Post Clamp Nut CAUTION: Refer to Fastener Caution . Tighten 9 N.m (80 lb in)
2	Auxiliary Negative Battery Engine Block Ground Bolt Tighten 25 N.m (18 lb ft)
3	Clamp
4	Auxiliary Negative Battery Cable

CAUTION
Refer to Fastener Caution .

Auxiliary Battery Negative Cable Replacement (TP2)

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the underhood fuse block cover (1).
Lift the fuse block retainers (2) from the locked position and rotate the retainers to the open position.
Reposition the fuse block and remove the battery positive connector (3) from the underhood fuse block base.
Remove the battery positive cable clip nuts (1) from the studs on the plenum front panel.
Remove the battery positive retainer clips (2) from the plenum front panel and the exhaust fluid container bracket.
Remove the cover to the battery fuse block.
Remove the battery positive cable nut (1) from the battery fuse block.
Remove the positive battery cable (2) from the vehicle.

Install the battery positive cable (2) to the battery fuse block with nut (1) and tighten to 10 N.m (89 lb in)
Install the battery positive cable clip nuts (1) to the studs on the plenum front panel and tighten to 3 N.m (27 lb in).
Install harness retainers (2) to the plenum and engine exhaust fluid container bracket.
Install the battery positive cable connector (3) to the underhood fuse block.
Ensure that the underhood fuse block retainers (2) are in the open position.
Position and engage the junction block to the 4 bracket pivots, push the retainers (2) down into the locked position.
Install the underhood fuse block cover.
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the underhood fuse block cover (1).
Lift the fuse block retainers (2) from the locked position and rotate the retainers to the open position.
Reposition the fuse block and remove the battery positive connector (3) from the underhood fuse block base.
Remove the battery positive cable retainers (1) from the studs on the plenum front panel.
Remove the cover to the battery fuse block.
Remove the battery positive cable nut (1) from the battery fuse block.
Remove the positive battery cable from the vehicle.

Install the battery positive cable to the battery fuse block with nut (1) and tighten to 10 N.m (89 lb in)
Install the battery positive cable retainers (1) to the upper plenum.Install the battery positive cable clip nuts (1) to the studs on the upper plenum.
Install the battery positive cable connector (3) to the underhood fuse block.
Ensure that the underhood fuse block retainers (2) are in the open position.
Position and engage the junction block to the 4 bracket pivots, push the retainers (2) down into the locked position.
Install the underhood fuse block cover.
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the underhood fuse block cover (1).
Lift the fuse block retainers (2) from the locked position and rotate the retainers to the open position.
Reposition the fuse block and remove the battery positive connector (3) from the underhood fuse block base.
Remove the battery positive cable connector (1) from the auxiliary relay.
Remove the battery positive cable nut (2) and terminal (3) from the auxiliary relay.
Remove the battery positive terminal nuts (1) and (2), from the mega fuse holder.
Disconnect the engine harness connector (4) from the battery positive cable.
Remove the retaining nuts (1) and cable clips (2), securing the cable to the upper plenum.
Remove the battery positive cable from the vehicle.

Install the battery positive cable (3) to the battery mega fuse holder with nuts (1) and (2). Tighten the nuts to 10 N.m (89 lb in)
Connect the engine harness connector (4) to the battery positive cable.
Install the battery positive cable to the studs on the upper plenum.
Install the cable retainers (2) and tighten the nuts (1) to 10 N.m (89 lb in)
Install the battery positive cable connector (3) to the underhood fuse block.
Ensure that the underhood fuse block retainers (2) are in the open position.
Position and engage the junction block to the 4 bracket pivots, push the retainers (2) down into the locked position.
Install the underhood fuse block cover.
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
If equipped with dual generators, remove the mega fuse nut (1) on top of the auxiliary battery.
Disconnect the generator battery jumper cable. Refer to «Generator Battery Jumper Cable Replacement (K76)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Battery Jumper Cable Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)
Loosen the auxiliary battery positive clamp nut (1) and remove the clamp from the battery post.
Remove the cable retainers (2) along the top of the fan shroud.
Remove the auxilliary battery positive harness clips (1) from the condensor hose and the transmission cooler hose.
Remove the mega fuse block nut (1) and the auxillary battery positive cable terminal (2), from the mega fuse block.

Install the auxilliary battery positive clamp to the battery post and tighten clamp nut (1) to 9 N.m (80 lb in)
If equipped with dual generators (K74), connect the generator jumper cable (3) to the mega fuse holder with the nut (1) and tighten to 9 N.m (80 lb in)
Install the auxilliary battery positive cable retainers (2) along the cooling fan shroud.
Install the auxiliary battery positive cable clips (1) to the condensor hose and the transmission cooler hose.
Install the auxiliary battery positive cable terminal (2) to the mega fuse block and tighten the nut (1) to 9 N.m (80 lb in)
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Scheme 8

Scheme 8: Battery Positive Junction Block Cable Replacement (Glow Plug Module - Diesel)

Callout	Component Name
Preliminary Procedures Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection (TP2) , Battery Negative Cable Disconnection and Connection (Single Battery) .
1	Mega-Fuse Holder Nut CAUTION: Refer to Fastener Caution . Tighten 9 N.m (80 lb in)
2	Battery Positive Junction Block Cable

CAUTION
Refer to Fastener Caution .

Battery Positive Junction Block Cable Replacement (Glow Plug Module - Diesel)

Scheme 9

Scheme 9: Battery Positive Junction Block Cable Replacement (Air Intake Heater - Diesel)

Callout	Component Name
Preliminary Procedures Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection (TP2) , Battery Negative Cable Disconnection and Connection (Single Battery) .
1	Junction Block Nut CAUTION: Refer to Fastener Caution . Tighten 9 N.m (80 lb in)
2	Battery Positive Nut (Intake Air Heater) Tighten 9 N.m (80 lb in)
3	Battery Positive Junction Block Cable

CAUTION
Refer to Fastener Caution .

Battery Positive Junction Block Cable Replacement (Air Intake Heater - Diesel)

Scheme 10

Scheme 10: Auxiliary Battery Positive Cable Replacement - Battery to Battery Relay (TP2)

Callout	Component Name
Preliminary Procedures Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection (TP2) , Battery Negative Cable Disconnection and Connection (Single Battery) .
1	Auxiliary Battery Positive Clamp Nut CAUTION: Refer to Fastener Caution . Tighten 9 N.m (80 lb in)
2	Auxiliary Battery Relay Nut Tighten 9 N.m (80 lb in)
3	Underhood Fuse Block Nut Tighten 9 N.m (80 lb in)
4	Auxiliary Battery Positive Cable

CAUTION
Refer to Fastener Caution .

Auxiliary Battery Positive Cable Replacement - Battery to Battery Relay (TP2)

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the mega fuse block nut (1).
Remove the battery positive cable (3) and the generator jumper cable terminal (2), from the mega fuse block.
Remove the generator nut (1).
Remove the generator jumper cable from the vehicle.

Install the generator jumper cable (2) to the generator with the nut (1) and tighten to 9 N.m (80 lb in)
Install the generator jumper cable terminal (2) and the battery positive cable (3), to the mega fuse block.
Install the mega fuse block nut (1) and tighten to 9 N.m (80 lb in)
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Scheme 11

Scheme 11: Generator Battery Jumper Cable Replacement (K76)

Callout	Component Name
Preliminary Procedures Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection (TP2) , Battery Negative Cable Disconnection and Connection (Single Battery) .
1	Mega-Fuse Holder Nut CAUTION: Refer to Fastener Caution . Tighten 9 N.m (80 lb in)
2	Auxiliary Generator Nut Tighten 9 N.m (80 lb in)
3	Generator Battery Jumper Cable

CAUTION
Refer to Fastener Caution .

Generator Battery Jumper Cable Replacement (K76)

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the right side front wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
Open the starter solenoid cable positive battery post cover.
Loosen the battery post clamp nut (1).
Remove the mega-fuse holder nut (2) and detach the battery positive cable terminal (3).
Remove the starter solenoid cable (4) from the battery.
Remove the starter solenoid cable retainer bolt (1) frome the right frame rail.
Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
Remove the starter solenoid nut (1) and the starter cable (2), from the vehicle.

Install the starter cable (2) and nut (1), to the starter.Tighten the nut to 9 N.m (80 lb in).
Install the starter solenoid cable retaining clip (2) and nut (1), to the right frame rail. Tighten the bolt to 25 N.m (18 lb ft).
Install the starter solenoid cable to the battery post and tighten the nut (1) to 9 N.m (80 lb in).
Install the battery positive terminal (3) to the mega-fuse holder and tighten nut (2) to 9 N.m (80 lb in).
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the right side front wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
Open the starter solenoid cable positive battery post cover.
Loosen the battery positive post clamp nut.
Remove the mega-fuse holder nuts (1) and (2). Detach the battery positive cables from the mega-fuse holder.
Remove the starter solenoid cable (4) from the battery.
Remove the starter solenoid cable retainer bolt (1) from the right frame rail.
Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
Remove the starter solenoid nut (1) and the starter cable terminal (2), from the vehicle.

Install the starter cable terminal (2) and nut (1), to the starter. Tighten the nut to 9 N.m (80 lb in).
Install the starter solenoid cable retaining clip (2) and nut (1), to the right frame rail. Tighten the bolt to 25 N.m (18 lb ft).
Install the starter solenoid cable clamp to the battery post and tighten the nut to 9 N.m (80 lb in).
Install the battery positive terminals (3) and (4) to the mega-fuse holder. Tighten the nuts (1) and (2) to 9 N.m (80 lb in).
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the right side front wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
Open the starter solenoid cable positive battery post cover.
Loosen the battery post clamp nut (1).
Remove the mega-fuse block nuts (2) and detach the generator jumper (3), intake air heater cable (4), glow plug cable 5 and the auxiliary battery positive cable (6).
Remove the starter solenoid cable from the battery.
Remove the starter solenoid cable nut (1) and detach the starter solenoid cable from the right side shock bracket.
Remove the starter solenoid cable from the vehicle.

Attach the starter solenoid cable retainer to the right side shock bracket.
Install the starter solenoid cable to the starter with nut (1) and tighten to 9 N.m (80 lb in).
Install the starter solenoid cable clamp to the battery post and tighten nut (1) to 9 N.m (80 lb in).
Install the generator jumper cable (3), intake air heater cable (4), glow plug cable (5) and the auxiliary battery positive cable (6) to the mega-fuse holder. Tighten nuts (2) to 9 N.m (80 lb in).
Install the right side front wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

WARNING

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Open the starter solenoid cable cover at the positive battery terminal.
Loosen the starter solenoid cable nut (5).
Remove the starter solenoid cable from the positive battery terminal.
Reposition the starter solenoid cable out of the way.
Remove the front fender rear upper brace bolts and brace.
Remove the battery hold down retainer bolt and retainer.
Remove the battery.

Install the battery.
Install the battery hold down retainer and bolt and tighten to 25 N.m (18 lb ft).
Install the front fender rear upper brace and bolts and tighten to 9 N.m (80 lb in).
Position the starter solenoid cable to the battery.
Install the starter solenoid cable to the positive battery terminal.
Tighten the starter solenoid cable nut (5) to 5 N.m (44 lb in).
Close the starter solenoid cable cover at the positive battery terminal.
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Scheme 12

Scheme 12: Auxiliary Battery Replacement

Callout	Component Name
Preliminary Procedure Disconnect the battery cables. Refer to Battery Negative Cable Disconnection and Connection (TP2) , Battery Negative Cable Disconnection and Connection (Single Battery) . Remove the front end sheet metal diagonal brace. Refer to Front End Sheet Metal Diagonal Brace Replacement .
1	Auxiliary Battery Hold Down Bolt CAUTION: Refer to Fastener Caution . Tighten 25 N.m (18 lb ft)
2	Auxiliary Battery Hold Down
3	Auxiliary Battery

CAUTION
Refer to Fastener Caution .

Auxiliary Battery Replacement

Remove the battery. Refer to «Battery Replacement»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the battery tray front support bolts.
Remove the battery tray front support.
Remove the nut securing the battery tray to the front fender inner panel.
Remove the 3 nuts securing the battery tray to the battery tray bracket.
Remove the battery tray from the vehicle.

Install the battery tray to the vehicle.
Install the 3 nuts securing the battery tray to the battery tray bracket and tighten to 20 N.m (15 lb ft).
Install the nut securing the battery tray to the front fender inner panel and tighten to 9 N.m (80 lb in).
Install the battery tray front support.
Install the battery tray front support bolts and tighten to 20 N.m (15 lb ft).
Install the battery. Refer to «Battery Replacement»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Scheme 13

Scheme 13: Auxiliary Battery Tray Replacement

Callout	Component Name
Preliminary Procedure Remove the auxiliary battery if equipped. Refer to Auxiliary Battery Replacement .
1	Auxiliary Battery Tray Bolts (Qty: 8) CAUTION: Refer to Fastener Caution . TIP: Note the length of the battery tray bolts when removing for proper reinstallation. The battery tray bolts vary in length. Tighten 9 N.m (80 lb in)
2	Auxiliary Battery Tray

CAUTION
Refer to Fastener Caution .

Auxiliary Battery Tray Replacement

WARNING

Disconnect the auxiliary battery negative cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Reposition the auxiliary battery positive cable boot (5) from the auxiliary battery relay stud.
Remove the auxiliary battery positive cable nut (6) from the battery relay stud.
Remove the auxiliary battery positive cable from the auxiliary battery relay.
Disconnect the auxiliary battery positive cable electrical connector (1) from the battery relay.
Reposition the auxiliary battery positive cable boot (5) from the auxiliary battery relay stud.
Remove the auxiliary battery positive cable nut (4) from the battery relay stud.
Remove the auxiliary battery positive cable from the auxiliary battery relay.
Remove the auxiliary battery relay nuts and relay.

Install the auxiliary battery relay and nuts and tighten to 9 N.m (80 lb in).
Install the auxiliary battery positive cable to the auxiliary battery relay.
Install the auxiliary battery positive cable nut (4) to the battery relay stud and tighten to 9 N.m (80 lb in).
Position the auxiliary battery positive cable boot (5) to the auxiliary battery relay stud.
Connect the auxiliary battery positive cable electrical connector (1) to the battery relay.
Install the auxiliary battery positive cable to the auxiliary battery relay.
Install the auxiliary battery positive cable nut (6) to the battery relay stud and tighten to 9 N.m (80 lb in).
Position the auxiliary battery positive cable boot (5) to the auxiliary battery relay stud.
Connect the auxiliary battery negative cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Remove the ground strap bolt from the rear of the left cylinder head.
Reposition the ground strap from the cylinder head.
Remove the ground strap nut from the stud at the front of dash.
Remove the ground strap from the stud.

Install the ground strap to the stud.
Install the ground strap nut to the stud at the front of dash and tighten to 9 N.m (80 lb in).
Position the ground strap to the rear of the left cylinder head.
Install the ground strap bolt and tighten to 16 N.m (12 lb ft).

Remove the engine wiring harness ground bolt.
Reposition the engine wiring harness ground and ground strap.
Remove the ground strap nut from the stud at the front of dash.
Remove the ground strap from the stud.

Install the ground strap to the stud.
Install the ground strap nut to the stud at the front of dash and tighten to 9 N.m (80 lb in).
Position the ground strap and engine wiring harness ground.
Install the engine wiring harness ground bolt tighten to 16 N.m (12 lb ft).

Scheme 14

Scheme 14: Engine Ground Strap Replacement (Diesel)

Callout	Component Name
Preliminary Procedures Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
1	Upper Plenum Ground Strap Nut CAUTION: Refer to Fastener Caution . Tighten 9 N.m (80 lb in)
2	Ground Strap Terminal
3	Engine Block Ground Strap Bolt Tighten 16 N.m (12 lb ft)
4	Engine Ground Strap

CAUTION
Refer to Fastener Caution .

Engine Ground Strap Replacement (Diesel)

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
For 2500 series vehicles, remove the front 2 oil pan skid plate bolts, loosen the rear 2 bolts and remove the skid plate, if equipped.
Remove the transmission cover bolt.
Remove the starter bolts.
Disconnect the engine wiring harness electrical connector (4) from the oil level sensor.
Slide the starter forward until the starter clears the transmission and properly support the starter.
Lower the vehicle half way.
Remove the right front wheel and tire. Refer to «Tire and Wheel Removal and Installation»(/gmc/sierra-2500/2012-2012/remont/wheel-tire-system/#tires-and-wheels) .
Remove the right front wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
Remove the engine wiring harness lead nut (1).
Remove the engine wiring harness lead terminal (2) from the starter.
Remove the starter solenoid cable clip bolt (2) from the frame.
Remove the starter solenoid cable nut (1).
Remove the starter solenoid cable (2) from the starter.
Remove the starter out through the wheel well opening.
If replacing the starter, unsnap the transmission cover from the starter.
If replacing the starter, remove the starter heat shield.

If the starter was replaced, install the starter heat shield.
If the starter was replaced, snap the transmission cover onto the starter.
Install the starter in through the wheel well opening.
Install the starter solenoid cable to the starter.
Install the starter solenoid cable nut (1). Tighten Tighten the nut to 9 N.m (80 lb in).
Position the starter solenoid cable clip to the frame and install the starter solenoid cable clip bolt (2). Tighten Tighten the bolt to 10 N.m (89 lb in).
Install the engine wiring harness lead terminal (2) to the starter.
Install the engine wiring harness lead nut (1). Tighten Tighten the nut to 3.4 N.m (30 lb in).
Position the starter into place.
Install the starter bolts. Tighten Tighten the bolts to 50 N.m (37 lb ft).
Install the right front wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
Install the right front wheel and tire. Refer to «Tire and Wheel Removal and Installation»(/gmc/sierra-2500/2012-2012/remont/wheel-tire-system/#tires-and-wheels) .
Raise and support the vehicle.
Connect the engine wiring harness electrical connector (4) to the oil level sensor.
Install the transmission cover bolt. Tighten Tighten the bolt to 9 N.m (80 lb in).
For 2500 series vehicles, install the oil pan skid plate and tighten the rear 2 bolts and install and tighten the front 2 bolts, if equipped. Tighten Tighten the bolts to 28 N.m (21 lb ft).
Lower the vehicle.
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
Remove the oil pan skid plate bolts and plate, if equipped.
Remove the starter solenoid cable clip bolt (2) from the frame.
Remove the starter motor bolts.
Remove the starter solenoid cable lead nut (1).
Remove the starter solenoid cable lead (2) from the starter.
Remove the engine wiring harness lead nut (2).
Remove the engine wiring harness lead (5) from the starter.
Remove the starter from the vehicle.
If replacing the starter, remove the starter heat shield.

If the starter was replaced, install the starter heat shield to the starter.
Position the starter to the vehicle.
Install the engine wiring harness lead (5) to the starter.
Install the engine wiring harness lead nut (2). Tighten Tighten the nut to 3.4 N.m (30 lb in).
Install the starter solenoid cable lead (2) to the starter.
Install the starter solenoid cable (1) nut. Tighten Tighten the nut to 9 N.m (80 lb in).
Install the starter motor bolts. Tighten Tighten the bolts to 50 N.m (37 lb ft).
Position the starter solenoid cable clip to the frame and install the starter solenoid cable clip bolt (2). Tighten Tighten the bolt to 10 N.m (89 lb in).
Position the oil pan skid plate and install the bolts, if equipped. Tighten Tighten the bolts to 28 N.m (21 lb ft).
Lower the vehicle.
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Scheme 15

Scheme 15: Starter Replacement (Diesel)

Callout	Component Name
Preliminary Procedures Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection (TP2) , Battery Negative Cable Disconnection and Connection (Single Battery) . Remove the right side front wheelhouse liner. Refer to Front Wheelhouse Liner Replacement - Right Side (GMC) , Front Wheelhouse Liner Replacement - Right Side (Chevrolet) Remove the catalytic converter. Refer to Catalytic Converter Replacement (Gen IV Engines with Exhaust Clamp) , Catalytic Converter Replacement (LGH /LML) , Catalytic Converter Replacement (L96 with E63) , Catalytic Converter Replacement (L96 with ZW9) , Catalytic Converter Replacement (L96 with Exhaust Flange) .
1	Starter Solenoid Cable Nut CAUTION: Refer to Fastener Caution . Tighten 9 N.m (80 lb in)
2	Engine Harness Starter Nut Tighten 4 N.m (35 lb in)
3	Engine Harness
4	Battery Positive Cable
5	Starter Bolts (Qty: 2) Tighten 85 N.m (63 lb ft)
6	Starter

CAUTION
Refer to Fastener Caution .

Starter Replacement (Diesel)

Starter Solenoid Switch Replacement (Diesel)

Removal Procedure

The starter switch is replaced with the starter assembly. Refer to Starter Replacement (Diesel) , Starter Replacement (V6) , Starter Replacement (V8) .

Remove the generator. Refer to «Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the drive belt tensioner. Refer to «Drive Belt Tensioner Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-43l) .
Remove the drive belt idler pulley. Refer to «Drive Belt Idler Pulley Replacement - Right Side»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-43l) .
Remove the generator bracket bolts and nut.
Remove the generator bracket.

Install the generator bracket onto the stud.
Install the generator bracket bolts and nut. Tighten Tighten the bolts/nut to 41 N.m (30 lb ft).
Install the drive belt idler pulley. Refer to «Drive Belt Idler Pulley Replacement - Right Side»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-43l) .
Install the drive belt tensioner. Refer to «Drive Belt Tensioner Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-43l) .
Install the generator. Refer to «Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Remove the generator. Refer to «Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the power steering pump. Refer to «Power Steering Pump Replacement (4.3L)»(/gmc/sierra-2500/2012-2012/remont/manual-power-steering/#power-steering-system) , «Power Steering Pump Replacement (L96)»(/gmc/sierra-2500/2012-2012/remont/manual-power-steering/#power-steering-system) , «Power Steering Pump Replacement (6.6L)»(/gmc/sierra-2500/2012-2012/remont/manual-power-steering/#power-steering-system) , «Power Steering Pump Replacement (4.8L, 5.3L, and 6.2L)»(/gmc/sierra-2500/2012-2012/remont/manual-power-steering/#power-steering-system) .
Remove the engine wiring harness clip bolt (3) are reposition the clip (1) away from the generator bracket.
Remove the generator bracket bolts.
Remove the generator bracket.

Position the generator bracket to the engine.
Install the generator bracket bolts. Tighten Tighten the bolts to 50 N.m (37 lb ft).
Position the engine wiring harness clip (1) to the generator bracket and install the engine harness clip bolt (3). Tighten Tighten the bolt to 9 N.m (80 lb in).
Install the power steering pump. Refer to «Power Steering Pump Replacement (4.3L)»(/gmc/sierra-2500/2012-2012/remont/manual-power-steering/#power-steering-system) , «Power Steering Pump Replacement (L96)»(/gmc/sierra-2500/2012-2012/remont/manual-power-steering/#power-steering-system) , «Power Steering Pump Replacement (6.6L)»(/gmc/sierra-2500/2012-2012/remont/manual-power-steering/#power-steering-system) , «Power Steering Pump Replacement (4.8L, 5.3L, and 6.2L)»(/gmc/sierra-2500/2012-2012/remont/manual-power-steering/#power-steering-system) .
Install the generator. Refer to «Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the fan assembly. Refer to fan replacement «Fan Replacement (Mechanical)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system__fan-replacement-mechanical) , «Fan Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system__fan-replacement-diesel) .
Remove the heater outlet pipe retainer (2) and nut (1).
Remove the engine harness stud clip nut (3) and engine harness retainer (4).
Remove the nuts (2) at the back of the glow plug module (3).
Remove the glow plug module bracket bolts (1) and reposition the glow plug module (3).
Remove the bolt (1) securing the fuel line retainer (2) to the generator bracket.
Remove the upper intake manifold brace bolt (1).
Remove the bolts (2) securing the upper intake manifold brace (3) to the generator bracket.
Remove the drive belt tensioner. Refer to «Drive Belt Tensioner Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .
Remove the generator. Refer to «Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the generator bracket nuts (1) and bolt (1) from the cylinder block.
Remove the generator bracket (3).
If replacing the generator bracket, remove the idler pulleys (4) and transfer to the new generator bracket.

Position the generator bracket to the engine and install the nuts (1) and bolt (2). Tighten to 50 N.m (37 lb ft).
Install the upper intake manifold brace bolt (1) and tighten to 25 N.m (17 lb ft).
Install the bolts (2) securing the upper intake manifold brace (3) to the generator bracket and tighten to 25 N.m (17 lb ft).
Install the bolt (1) securing the fuel line retainer (2) to the generator bracket and tighten to 25 N.m (17 lb ft).
Install the engine harness stud clip nut (3) and engine harness retainer (4) and tighten to 10 N.m (89 lb in).
Install the heater outlet pipe retainer (2) and nut (1) and tighten to 25 N.m (17 lb ft).
Position the glow plug module on top of the generator bracket and tighten the nuts (2) and bolts (1) to 25 N.m (17 lb ft).
Install the drive belt tensioner. Refer to «Drive Belt Tensioner Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .
Install the generator. Refer to «Generator Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V6)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Generator Replacement (V8)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Install the fan assembly. Refer to «Fan Replacement (Mechanical)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system__fan-replacement-mechanical) , «Fan Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system__fan-replacement-diesel) .
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Remove the auxiliary generator. Refer to «Auxiliary Generator Replacement (KD9)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the auxiliary generator bracket bolt (2).
Remove the auxiliary generator bracket (1).

Position the auxiliary generator bracket (2) to the air conditioning (A/C) bracket.
Install the auxiliary generator bracket bolt (1). Tighten Tighten the bolt to 50 N.m (37 lb ft).
Install the auxiliary generator. Refer to «Auxiliary Generator Replacement (KD9)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the air cleaner outlet resonator. Refer to «Air Cleaner Outlet Resonator Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-43l-repair-instructions) .
Remove the drive belt. Refer to «Drive Belt Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-43l) .
Remove the engine wiring harness clip (1) from the air conditioning (A/C) compressor/condenser hose bracket.
Remove the A/C compressor and condenser hose bracket bolt (2).
Remove the heater outlet hose clamp bolt (1) at the generator bracket.
Disconnect the engine wiring harness electrical connector (5) from the generator.
Reposition the engine wiring harness boot (6).
Remove the engine wiring harness nut (3) from the generator.
Remove the engine wiring harness lead (4) from the generator stud.
Remove the generator bolts.
Reposition the heater outlet, and AC compressor/condenser hoses as necessary in order to remove the generator.
Remove the generator from the generator bracket.

Install the generator into the generator bracket.
Position the heater outlet, and AC compressor/condenser hoses as necessary.
Install the generator bolts. Tighten Tighten the bolts to 50 N.m (37 lb ft).
Install the engine wiring harness lead (4) to the generator stud.
Install the engine wiring harness nut (3) to the generator. Tighten Tighten the nut to 9 N.m (80 lb in).
Position the engine wiring harness boot (6) over the generator stud.
Connect the engine wiring harness electrical connector (5) to the generator.
Install the heater outlet hose clamp bolt (1) at the generator bracket. Tighten Tighten the bolt to 25 N.m (18 lb ft).
Install the A/C compressor and condenser hose bracket bolt (2). Tighten Tighten the bolt to 25 N.m (18 lb ft).
Instal the engine wiring harness clip (1) to the A/C compressor/condenser hose bracket.
Install the drive belt. Refer to «Drive Belt Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-43l) .
Install the air cleaner outlet resonator. Refer to «Air Cleaner Outlet Resonator Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-43l-repair-instructions) .
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the intake manifold sight shield. Refer to «Upper Intake Manifold Sight Shield Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-repair-instructions-on-vehicle) .
Remove the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-repair-instructions-on-vehicle) .
Disconnect the engine harness electrical connector (3) from the generator.
Reposition the generator battery jumper cable boot (3).
Remove the generator battery jumper cable nut (2) from the generator.
Remove the generator battery jumper cable terminal (1) from the generator stud.
Remove the generator bolts.
Remove the generator.

Install the generator.
Install the generator bolts. Tighten Tighten the bolts to 55 N.m (41 lb ft).
Install the generator battery jumper cable terminal (1) to the generator stud.
Install the generator battery jumper cable nut (2) to the generator. Tighten Tighten the nut to 9 N.m (80 lb in).
Position the generator battery jumper cable boot (3).
Connect the engine harness electrical connector (3) to the generator.
Install the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-repair-instructions-on-vehicle) .
Install the intake manifold sight shield. Refer to «Upper Intake Manifold Sight Shield Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-repair-instructions-on-vehicle) .
Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

Disconnect the negative battery. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
Remove the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Engine Coolant Fan Upper Shroud Replacement (Mechanical)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
Remove the drive belt. Refer to «Drive Belt Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .
Uncover the B+ terminal (2) by sliding away the protective boot (1).
Remove the generator B+ terminal nut (2) and the electrical connector (4).
Remove the generator bolts (1) and generator (2) from the generator bracket.

Install the generator (2) to the generator bracket and tighten the generator mounting bolts (1) to 50 N.m (37 lb ft)
Connect the generator electrical connector (4).
Install the battery positive B+ cable terminal (3) to the generator stud and tighten to 10 N.m (89 lb in)
Slide the protective boot (1) back onto the terminal stud.
Install the drive belt. Refer to «Drive Belt Replacement»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .
Install the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (Diesel)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Engine Coolant Fan Upper Shroud Replacement (Mechanical)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
Connect the battery negative cable. Refer to «Battery Negative Cable Disconnection and Connection (TP2)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system) , «Battery Negative Cable Disconnection and Connection (Single Battery)»(/gmc/sierra-2500/2012-2012/remont/charging-system/#battery-charging-system-and-starting-system)

WARNING