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Chevrolet Silverado / GMC Sierra. Manual - part 2926
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
Erratic wheel speed sensors can cause this condition to occur. Monitor the wheel speeds using the
EBCM scan tool data list.
Circuit/System Testing
1. Monitor the wheel speed sensors using the EMCM scan tool data list. If the wheel speeds
are erratic or there is a large difference between front and rear then diagnose and repair as
necessary. Check for EBCM DTCs as they have likely set for wheel speed performance.
2. If nothing is found with wheel speed performance then the clutches may be excessively
warn. Refer to Transfer Case Disassemble.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Transfer Case Disassemble
TRANSFER CASE SHIFT CONTROL SWITCH INDICATOR ALWAYS ON - TWO OR MORE
Diagnostic Instructions
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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
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 in ignition off disconnect connector X1 at the transfer case control module and turn the
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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.
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
Component Connector End Views
Electrical Information Reference
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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 in ignition off disconnect connector X1 at the transfer case control module and turn the
ignition on. With a jumper wire probe the indicator control circuit of the affected indicator
and take the other end of the jumper to ground. If the indicator comes on then replace the
transfer case control module, program, and perform the motor learn procedure
2. If the affected indicator did not come on then check the indicator control circuit for an open
or high resistance. If the circuit checks 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
SERVICE INDICATOR ALWAYS ON
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.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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