Content .. 2876 2877 2878 2879 ..
Chevrolet Silverado / GMC Sierra. Manual - part 2878
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
Scan Tool Data List
Scan Tool Data Definitions
Circuit/System Testing
1. If this is occurring without DTC C0379 setting it is likely related to a mechanical issue.
Refer to Four-Wheel Drive Does Not Disengage .
2. If no mechanical issue is found replace the front axle actuator.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for TCSCM replacement, setup, and programming
Transfer Case High/Low Clutch Reset
Four-Wheel Drive Does Not Engage
Four-Wheel Drive Does Not Disengage
Front Drive Axle Actuator Replacement
TRANSFER CASE SHIFT CONTROL SWITCH INOPERATIVE
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.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 1625/1626-NQF - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Circuit/System Description
The active transfer case mode switch circuit consists of 5 modes. The transfer case shift control
module supplies 5 volts to the switch through the 5-volt reference circuit. The current travel
through the resistor of the currently active mode. The current is then returned to the transfer case
shift control module through the switch signal circuit.
The transfer case shift control module constantly monitors this signal voltage to determine the
condition of the mode switch circuit.
When each of the modes are selected they complete a circuit through their own specific resistor.
The transfer case shift control module continuously monitors the switch input to determine
whether the Neutral, 2HI, 4HI, or 4LO mode was selected by the driver.
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
Scan Tool Data List
Scan Tool Data Definitions
Diagnostic Aids
If the 5-volt reference or the switch signal wire are shorted to ground the scan tool can show up
to 7.5 volts.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 1625/1626-NQF - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Circuit/System Testing
1. Review the scan tool data list mode switch selected and select difference mode with the
transfer case shift control switch. Does the mode switch selected parameter on the scan tool
change as you change modes on the switch?
2. If the modes change according to the scan tool replace the transfer case control module,
reprogram, complete the motor learn procedure. If the modes on the scan tool do not change
replace the switch.
Repair Procedures
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
TRANSFER CASE SHIFT CONTROL SWITCH INDICATOR ALWAYS ON - TWO OR MORE
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.
Circuit/System Description
The indicator circuits consists of an interior lights dimming circuit and an indicator control
circuit. When a mode has been selected, current is supplied to the indicator by the interior lights
dimming circuit, traveling through the indicator LED, at which time the transfer case shift control
module supplies the ground through the indicator lamp control circuit.
Reference Information
Schematic Reference
Transfer Case Control Schematics
Connector End View Reference
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 1625/1626-NQF - 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 indicator control circuit will cause the indicator to remain on at all
times.
Circuit/System Testing
1. With the ignition off disconnect connector X1 at the transfer case control module and turn
the ignition on. If the affected indicator goes out replace the transfer case control module,
program, and perform the motor learn procedure.
2. If the affected indicator did not go out check for a short to ground on the affected indicator
control circuit. If this checks as good then replace the transfer case shift control switch.
Repair Procedures
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
TRANSFER CASE SHIFT CONTROL SWITCH INDICATOR INOPERATIVE - ONE OR MORE
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 1625/1626-NQF - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Content .. 2876 2877 2878 2879 ..