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Chevrolet Silverado / GMC Sierra. Manual - part 2911
Circuit/System Description
The All Wheel Drive (AWD) indicator circuit consists of an indicator lamp feed circuit and an
AWD indicator lamp control circuit. When the AWD mode has been selected, current is supplied
to the AWD indicator lamp by the indicator lamp feed circuit, traveling through the AWD
indicator lamp LED, at which time the transfer case shift control module supplies the ground
through the AWD indicator lamp control circuit.
Conditions for Running the DTC
The ignition is ON.
System voltage is 10-18 volts.
Conditions for Setting the DTC
The system monitors the voltage on the AWD indicator control circuit.
If the system detects a voltage of 2 volts or less for 1.5 seconds when the AWD indicator is
not commanded, the DTC is logged.
If the system detects a voltage of 4.5 volts or more when the AWD indicator is commanded,
the DTC is logged.
Action Taken When the DTC Sets
The SERVICE 4WD indicator is not commanded on for this DTC.
Conditions for Clearing the DTC
The transfer case shift control module clears the DTC if the condition for setting the DTC is
not currently present.
A history DTC clears after 40 consecutive warm up cycles without a fault present.
History DTCs can be cleared using a scan tool.
Reference Information
Schematic Reference
Transfer Case Control Schematics
Connector End View Reference
AWD Indicator Circuit
06
06
01
-
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Component Connector End Views
Electrical Information Reference
Circuit Testing
Connector Repairs
Testing for Intermittent Conditions and Poor Connections
Wiring Repairs
Scan Tool Reference
Scan Tool Data List
Scan Tool Data Definitions
Diagnostic Aids
A short to ground on the AWD indicator control circuit will cause the AWD indicator to remain
on at all times. An open or high resistance will cause the AWD indicator to be inoperative during
the 2 second bulb check.
Circuit/System Testing
Check the interior dimming circuit pin 2 at the transfer case shift control switch for voltage for
the 2 seconds after turning the ignition on during the bulb check.
If less than battery voltage check the interior dimming circuit for an open or high resistance.
If the voltage is low or non existence and the circuit tests good replace the BCM. If the
interior dimming circuit and BCM test good go to the next step.
If the AWD indicator is on at all times check the AWD indicator control circuit for a short
to ground. If the AWD indicator is inoperative during bulb check, check the AWD indicator
control circuit for an open or high resistance or short to voltage. If the circuit checks good
continue to the next step.
With the ignition on shift the transmission to neutral and using transfer case output controls
attempt to command the AWD indicator off and on. If the AWD indicator is still inoperative
short to AWD indicator to ground, if the AWD indicator lights replace the module. If the
AWD indicator is still inoperative replace the switch.
Repair Procedures
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Transfer Case Shift Control Switch Replacement (Without SLT) or Transfer Case
Shift Control Switch Replacement (With SLT)
Control Module References for TCSCM replacement, setup, and programming
Transfer Case High/Low Clutch Reset
DTC B0775
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC B0775 01
4 High Indicator Circuit Short to Battery
DTC B0775 06
4 High Indicator Circuit Short to Ground or Open
Diagnostic Fault Information
Circuit/System Description
The 4 high indicator circuit consists of an indicator lamp feed circuit and an 4 high indicator lamp
control circuit. When the 4 high mode has been selected, current is supplied to the 4 high
indicator lamp by the interior lights dimming circuit, traveling through the 4 high indicator lamp
LED, at which time the transfer case shift control module supplies the ground through the 4 high
indicator lamp control circuit.
Conditions for Running the DTC
Circuit
Short to
Ground
Open/High
Resistance
Short to
Voltage
Signal
Performance
4 High Indicator Circuit
DTC B0775
06
DTC B0775
06
DTC B0775
01
-
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
The ignition is ON.
System voltage is 10-18 volts.
Conditions for Setting the DTC
The system monitors the voltage on the 4 high indicator control circuit.
If the system detects a voltage of 2 volts or less for 1.5 seconds when the 4 high indicator is
not commanded, the DTC is logged.
If the system detects a voltage of 4.5 volts or more when the 4 high indicator is commanded,
the DTC is logged.
Action Taken When the DTC Sets
The SERVICE 4WD indicator is not commanded on for this DTC.
Conditions for Clearing the DTC
The transfer case shift control module clears the DTC if the condition for setting the DTC is
not currently present.
A history DTC clears after 40 consecutive warm up cycles without a fault present.
History DTCs can be cleared using a scan tool.
Reference Information
Schematic Reference
Transfer Case Control Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
Circuit Testing
Connector Repairs
Testing for Intermittent Conditions and Poor Connections
Wiring Repairs
Scan Tool Reference
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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