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Transfer Case - Nvg 261-np2 Chevrolet Cab & Chassis Silverado 3500

Transfer Case 11 illustrations ~4447 words

Fastener Tightening Specifications

ApplicationSpecification
MetricEnglish
Control Rod Adjusting Bolt15 N.m11 lb ft
Crossmember Bolt70 N.m52 lb ft
Gear Shift Indicator Switch27 N.m20 lb ft
Transfer Case Adapter Bolt50 N.m37 lb ft
Transfer Case Adapter Nut50 N.m37 lb ft
Transfer Case Control Lever Bezel Screw2 N.m18 lb in
Transfer Case Drain/Fill Plug20 N.m15 lb ft
Transfer Case Shield Bolt/Screw20 N.m15 lb ft
Transfer Case Control Lever Bolt12 N.m106 lb in
Transfer Case Speed Sensor15 N.m11 lb ft
Transmission Mount Bolt47 N.m35 lb ft
Transmission Mount Nut40 N.m30 lb ft

Fastener Tightening Specifications

Capacities - Approximate Fluid

LubricantSpecification
MetricEnglish
Dexron® III Automatic Transmission Fluid, GM P/N 12346143 (Canadian P/N 10952622)1.9 liters2.0 quarts

Capacities - Approximate Fluid

Scheme 1

Scheme 1: Transfer Case Control Schematics
Scheme 1: Transfer Case Control Schematics

Scheme 2

Scheme 2: Transfer Case Control Component Views
Scheme 2: Transfer Case Control Component Views
CalloutComponent Name
1C350
2Transfer Case Shift Control Switch Connector
3Vehicle Speed Sensor (VSS)
4Transfer Case - NVG 261 - NP2

Scheme 3

Scheme 3
Scheme 3
CalloutComponent Name
1Ground 110 (G110)
2Vent Tube
3Vent Tube Connection
4Front Axle Actuator
5Front Axle Actuator Connector
6Left Inner Fender

Scheme 4

Scheme 4
Scheme 4
CalloutComponent Name
1Vent Tube
2Vent Tube Connection
3Front Axle Actuator
4Front Axle Actuator Connector
5Front Drive Axle Assembly (Mount)
6Ground 110 (G110)
7Left Inner Fender

Transfer Case Control Connector End Views

Transfer Case Shift Control Switch Connector Part Information 12059595 3-Way F Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A BK 2150 Ground B GY/BK 1694 4WD Low Signal C L-BU 1296 Axle Actuator-Control

Front Axle Actuator Connector Part Information 15324541 4-Way F Metri-Pack 150 Series Sealed (BU) Pin Wire Color Circuit No. Function A BK/WH 1695 Axle Switch Signal B L-BU 1296 Axle Actuator-Control C BN 241 Ignition 3 Voltage D - - Not Used E BK 2150 Ground

Diagnostic Starting Point - Transfer Case

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

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

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

Symptoms - Transfer Case

IMPORTANTReview the system operation in order to familiarize yourself with the system functions. Refer to Transfer Case Description and Operation .

Visual/Physical Inspection

  1. Inspect for aftermarket devices which could affect the operation of the Manual Selectable 4-Wheel Drive System. Refer to «Checking Aftermarket Accessories»(ref-197325-S26768357732005101100000) in Wiring Systems.
  2. Inspect the easily accessible, or the visible system components for obvious damage or conditions which could cause the symptom.
  3. Ensure all mechanical components are operative before diagnosing the electrical portion of the system.
  4. In order to determine whether the vehicle is in 2-wheel drive (2WD) or 4-wheel drive (4WD), lift the vehicle so that the wheels can spin freely. With the transfer case control lever in 2HI, turn the rear propshaft. If the front propshaft does not move with the rear, the vehicle is in 2HI. If the tires and the front propshaft moves, the transfer case is actually in 4WD.
  5. Make sure that the 4WD fuse is not open. If open, locate and repair the source of the overload. Refer to «Testing for Short to Ground»(ref-197325-S06638163762005101100000) in Wiring Systems. Replace the fuse.

Intermittent

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

Symptom List

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

  1. «Four-Wheel Drive Does Not Disengage»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2)
  2. «Four-Wheel Drive Does Not Engage»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2)
  3. «4WD Indicator Inoperative»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2)
  4. «4WD Indicator Always On»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2)
  5. «Transfer Case Popping Noise»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2__transfer-case-popping-noise)
  6. «Transfer Case Whine or Rumble Noise»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2__transfer-case-whine-or-rumble-noise)
  7. «Transfer Case Growl or Grinding Noise»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2__transfer-case-growl-or-grinding-noise)
  8. «Transfer Case Clunk in 2HI Only»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2__transfer-case-clunk-in-2hi-only)
  9. «Transfer Case Clunk in 4HI»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2__transfer-case-clunk-in-4hi)
  10. «Transfer Case Clunk in 4LO»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2__transfer-case-clunk-in-4lo)
  11. «Transfer Case Shudder or Binding»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2__transfer-case-shudder-or-binding)
  12. «Transfer Case Will Not Shift»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2__transfer-case-will-not-shift)
  13. «Transfer Case Jumps Out of Gear»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2__transfer-case-jumps-out-of-gear)
  14. «Transfer Case Leak Diagnosis»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2__transfer-case-leak-diagnosis)

Circuit Description

The front axle control circuit consists of an electric motor actuator which engages and disengages the front axle. The front axle actuator consists of the following components within the actuator assembly

  1. A permanent magnetic motor
  2. A worm gear controlled plunger
  3. A front axle switch
  4. An electronic control circuit

The front axle actuator consists of the following circuits

  1. An ignition 3 voltage circuit
  2. A ground circuit
  3. An axle actuator control circuit
  4. An axle switch signal circuit

Whenever a shift to 4WD is selected, the transfer case switch engages the front axle by grounding the axle actuator control circuit.

Test Description

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

  1. 2: Tests for proper ignition 3 voltage to the front axle actuator.
  2. 3: Tests for proper ground at the front axle actuator.
  3. 4: Tests the axle actuator control circuit and transfer case switch for a short to ground.
  4. 5: Tests the axle actuator control circuit for a short to ground.
StepActionValuesYesNo
Schematic Reference: Transfer Case Control Schematics
1Did you perform a Diagnostic System Check - Vehicle?Go to Step 2Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2Turn OFF the ignition. Disconnect the front axle actuator. Ensure the 4-wheel drive (4WD) control lever is in the 2-wheel drive (2WD) position. Turn ON the ignition, with the engine OFF. With a DMM, test the ignition 3 voltage circuit for proper voltage. Does the voltage measure within the specified value?9-14 VGo to Step 3Go to Step 6
3Disconnect the front axle actuator. Turn ON the ignition, with the engine OFF. With a DMM, measure the voltage between the ignition 3 voltage circuit and the ground circuit at the front axle actuator. Does the voltage measure within the specified value?9-14 VGo to Step 4Go to Step 7
4Turn ON the ignition, with the engine OFF. Shift the transfer case into 2HI. Connect a test lamp between the ignition 3 voltage circuit and the axle actuator control circuit, at the front axle actuator. Does the test lamp illuminate?Go to Step 5Go to Step 9
5Disconnect the transfer case switch. Connect a test lamp between the ignition 3 voltage circuit and the axle actuator control circuit at the front axle actuator. Does the test lamp illuminate?Go to Step 8Go to Step 10
6Repair the open in the ignition 3 voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair?Go to Step 11
7Repair the open in the ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair?Go to Step 11
8Repair the short to ground in the axle actuator control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 11
9Replace the front axle actuator. Refer to Electric Motor Actuator Replacement in Front Drive Axle. Did you complete the replacement?Go to Step 11
10Replace the transfer case switch. Refer to Transfer Case Gear Indicator Switch Replacement . Does the scan tool display the status Front Axle Switch Locked?Go to Step 11
11Operate the vehicle in order to determine if the symptom has been corrected. Is the symptom still present?Go to Step 2System OK

Four-Wheel Drive Does Not Disengage

The front axle control circuit consists of an electric motor actuator which engages and disengages the front axle. The front axle actuator consists of the following components within the actuator assembly

  1. A permanent magnetic motor
  2. A worm gear controlled plunger
  3. A front axle switch
  4. An electronic control circuit

The front axle actuator consists of the following circuits

  1. An ignition 3 voltage circuit
  2. A ground circuit
  3. An axle actuator control circuit
  4. An axle switch signal circuit

Whenever a shift to 4WD is selected, the transfer case switch engages the front axle by grounding the axle actuator control circuit.

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

  1. 2: Tests for proper ignition 3 voltage to the front axle actuator.
  2. 3: Tests for proper ground at the front axle actuator.
  3. 4: Tests for proper ground at the axle actuator control circuit through the transfer case switch.
  4. 5: Tests the transfer case switch ground circuit for an open.
  5. 6: Tests the transfer case switch for proper operation.
StepActionValuesYesNo
Schematic Reference: Transfer Case Control Schematics
1Did you perform a Diagnostic System Check - Vehicle?Go to Step 2Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2Turn OFF the ignition. Disconnect the front axle actuator. Ensure the 4-wheel drive (4WD) control lever is in the 4WD position. Turn ON the ignition with the engine OFF. With a DMM, test the ignition 3 voltage circuit for proper voltage. Does the voltage measure within the specified value?9-14 VGo to Step 3Go to Step 7
3Disconnect the front axle actuator. Turn ON the ignition, with the engine OFF. With a DMM, measure the voltage between the ignition 3 voltage circuit and the ground circuit at the front axle actuator. Does the voltage measure within the specified value?9-14 VGo to Step 4Go to Step 8
4Turn ON the ignition, with the engine OFF. Shift the transfer case into 4HI. Connect a test lamp between the ignition 3 voltage circuit and the axle actuator control circuit, at the front axle actuator. Does the test lamp illuminate?Go to Step 11Go to Step 5
5Disconnect the transfer case switch. Connect a test lamp from the ignition 3 voltage circuit to the transfer case switch ground circuit Does the test lamp illuminate?Go to Step 6Go to Step 9
6With the control lever in the 4WD position, test for continuity across the transfer case switch. Is continuity present across the switch?Go to Step 10Go to Step 12
7Repair the open in the ignition 3 voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair?Go to Step 13
8Repair the open in the ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair?Go to Step 13
9Repair the open in the transfer case switch ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair?Go to Step 13
10Repair the open in the axle actuator control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair?Go to Step 13
11Replace the front axle actuator. Refer to Electric Motor Actuator Replacement in Front Drive Axle. Did you complete the replacement?Go to Step 13
12Replace the transfer case switch. Refer to Transfer Case Gear Indicator Switch Replacement . Did you complete the repair?Go to Step 13
13Operate the vehicle in order to determine if the symptom has been corrected. Is the symptom still present?Go to Step 2System OK

Four-Wheel Drive Does Not Engage

The 4WD indicator lamp is located in the instrument cluster. Ignition 1 voltage is supplied to the instrument panel cluster (IPC) when the ignition switch is in the START or RUN position. When the vehicle is in START or RUN and the powertrain control module (PCM) receives the axle switch signal from the front axle actuator, the PCM sends a class 2 signal to the instrument cluster turning on the 4WD indicator. The 4WD indicator will stay on as long as the axle switch signal input is present.

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

  1. 2: Tests for an intermittent condition.
  2. 3: Determines whether the failure is the result of a faulty 4WD system.
  3. 4: Determines if the failure is the result of a faulty instrument cluster.
  4. 5: Determines if the failure is the result of a faulty PCM.
StepActionValue(s)YesNo
Schematic Reference: Transfer Case Control Schematics
1Did you perform A Diagnostic System Check - Vehicle?Go to Step 2Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2Verify the fault is present. Does the system operate normally?Go to Testing for Intermittent Conditions and Poor Connections in Wiring SystemsGo to Step 3
3Does the front axle disengage when the 4WD control lever is in the 2WD position?Go to Step 4Go to Four-Wheel Drive Does Not Disengage
4Turn ON the ignition, with the engine OFF. Install a scan tool. Use the scan tool to command the 4WD indicator OFF. Does the 4WD indicator turn OFF?Go to Step 5Go to Step 8
5Test the axle switch signal circuit for voltage at the PCM. Does the voltage measure within the specified value?9-14 VGo to Step 6Go to Step 7
6Inspect the axle switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. If OK, replace the front axle actuator. Refer to Electric Motor Actuator Replacement in Front Drive Axle. Did you complete the replacement?Go to Step 9
7Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, set-up, and programming. Did you complete the replacement?Go to Step 9
8Replace the instrument panel cluster. Refer to Instrument Panel Cluster (IPC) Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement?Go to Step 9
9Operate the vehicle in order to determine if the symptom has been corrected. Is the symptom still present?System OKGo to Step 2

4WD Indicator Always On

The 4WD indicator lamp is located in the instrument cluster. Ignition 1 voltage is supplied to the instrument panel cluster (IPC) when the ignition switch is in the START or RUN position. When the vehicle is in START or RUN and the powertrain control module (PCM) receives the axle switch signal from the front axle actuator, the PCM sends a class 2 signal to the instrument cluster turning on the 4WD indicator. The 4WD indicator will stay on as long as the axle switch signal input is present.

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

  1. 2: Tests for an intermittent condition.
  2. 3: Determines whether the failure is the result of a faulty front axle circuit or the instrument cluster.
  3. 4: Tests for proper signal voltage to the PCM.
  4. 5: Tests for proper ignition 1 voltage to the instrument cluster.
StepActionValue(s)YesNo
Schematic Reference: Transfer Case Control Schematics
1Did you perform a Diagnostic System Check - Vehicle?Go to Step 2Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2Verify the fault is present. Does the system operate normally?Go to Testing for Intermittent Conditions and Poor Connections in Wiring SystemsGo to Step 3
3Turn ON the ignition, with the engine OFF. Install a scan tool. Use the scan tool to command the 4WD indicator ON. Does the 4WD indicator turn ON?Go to Step 4Go to Step 5
4Ensure the 4WD control lever is in the 4WD position. Test the axle switch signal circuit for proper voltage at the PCM. Does the voltage measure within the specified value?9-14 VGo to Step 8Go to Step 9
5Test the ignition 1 voltage circuit for a proper voltage at the instrument cluster. Does the voltage measure within the specified value?9-14 VGo to Step 6Go to Step 7
6Replace the instrument panel cluster. Refer to Instrument Panel Cluster (IPC) Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement?Go to Step 10
7Repair an open or high resistance in the ignition 1 voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair?Go to Step 10
8Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, set-up, and programming. Did you complete the replacement?Go to Step 10
9Inspect the axle switch signal circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. If OK, replace the front axle actuator. Refer to Electric Motor Actuator Replacement in Front Drive Axle. Did you complete the replacement?Go to Step 10
10Operate the vehicle in order to determine if the symptom has been corrected. Is the symptom still present?System OKGo to Step 2

4WD Indicator Inoperative

Transfer Case Popping Noise

CauseCorrection
DEFINITION: A faulty internal transfer case component that causes a popping noise in the transfer case. Review the Symptoms - Transfer Case and perform the necessary inspections.
Chain jumpReplace the chain and sprockets. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair. Replace the shaft bearings. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair. Inspect for damaged components caused by metal debris. Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair.

Transfer Case Popping Noise

Transfer Case Whine or Rumble Noise

CauseCorrection
DEFINITION: A faulty internal transfer case component that causes a whine noise in the transfer case. Review the Symptoms - Transfer Case and perform the necessary inspections.
Faulty bearingsInspect all bearings and journals. Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace any faulty bearings and any components with faulty bearing journals. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.

Transfer Case Whine or Rumble Noise

Transfer Case Growl or Grinding Noise

CauseCorrection
DEFINITION: A faulty internal transfer case component that causes a growl or grinding noise in the transfer case while the vehicle is turning or in a four wheel drive mode. Review the Symptoms - Transfer Case and perform the necessary inspections.
High/low planetary carrier assemblyInspect the high/low planetary carrier planetary gears for the following conditions: Chipped, bent or deformed teeth Planetary gear bushings worn Planetary gear thrust washers missing Seized or binding planetary gears Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the high/low planetary carrier assembly if any of the above conditions exist. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Input gearInspect the input gear teeth for excessive wear or damage. Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the input gear if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Thrust washersInspect for missing or damaged thrust washers for the input gear. Inspect the thrust washers for galling. Replace the thrust washers if faulty and the mating component if damaged. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Annulus gearInspect the annulus gear teeth for the following conditions: Damage Chipped teeth Excessive wear Metal embedded in the root of the teeth Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the front case half if the annulus gear is faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.

Transfer Case Growl or Grinding Noise

Transfer Case Clunk in 2HI Only

CauseCorrection
DEFINITION: During acceleration or deceleration, a clunk is heard or felt in the transfer case. Review the Symptoms - Transfer Case and perform the necessary inspections.
Incorrect fluid level or incorrect fluidInspect the transfer case for the correct fluid level. Refer to Transfer Case Fluid Replacement . Inspect the transfer case for the correct type of fluid. Flush the transfer case and fill with the correct fluid, if required.
Excessive clearance between the slip yoke and the rear output shaftInspect for the following conditions: Worn slip yoke splines Worn rear output shaft splines Repair or replace the following components, if faulty. Replace the slip yoke. Refer to Propeller Shaft Replacement - One Piece and Propeller Shaft Replacement - Two Piece in Propeller Shaft. Replace the rear output shaft. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Excessive clearance between the slip yoke and the rear bushingInspect for the following conditions: Worn rear bushing Worn slip yoke bushing journal Replace the slip yoke, if required. Refer to Propeller Shaft Replacement - One Piece or Propeller Shaft Replacement - Two Piece in Propeller Shaft. Replace the rear bushing if worn. Refer to Transfer Case Output Shaft Seal Replacement - Rear .
Input gear thrust washersInspect for worn or missing input gear thrust washers. Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the thrust washers as required. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Worn high speed teeth on the range sleeveInspect for worn high speed teeth on the range sleeve. Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the range sleeve if worn. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Rear output shaft bearing outer retaining ringInspect for the following conditions: Proper installation of the rear output shaft bearing retaining ring Excessive wear or damaged retaining ring groove in the rear case half Repair or replace the following components if found faulty: Properly install a new rear output shaft bearing outer retaining ring. Replace the rear case half if the retaining ring groove is excessively worn. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.

Transfer Case Clunk in 2HI Only

Transfer Case Clunk in 4HI

CauseCorrection
DEFINITION: During acceleration or deceleration, a clunk is heard or felt in the transfer case while in the 4HI range only. Review the Symptoms - Transfer Case and perform the necessary inspections.
Incorrect fluid level or incorrect fluidInspect the transfer case for the correct fluid level. Refer to Transfer Case Fluid Replacement . Inspect the transfer case for the correct type of fluid. Flush the transfer case and fill with the correct fluid, if required. Refer to Transfer Case Fluid Replacement .
Input gear thrust washersInspect for worn or missing input gear thrust washers. Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the thrust washers as required. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
2/4 Wheel drive synchronizer assemblyInspect the synchronizer for the following conditions: The synchronizer hub internal teeth to rear output shaft splines for excessive looseness caused by wear The synchronizer sleeve engagement teeth to the synchronizer gear for wear Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the synchronizer assembly if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Rear output shaft bearing outer retaining ringInspect for the following conditions: Proper installation of the rear output shaft bearing retaining ring Excessive wear or damaged retaining ring groove in the rear case half Repair or replace the following components if faulty: Properly install a new rear output shaft bearing outer retaining ring. Replace the rear case half if the retaining ring groove is excessively worn. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Worn high speed teeth on the range sleeveInspect for worn high speed teeth on the range sleeve. Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the range sleeve if worn. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.

Transfer Case Clunk in 4HI

Transfer Case Clunk in 4LO

CauseCorrection
DEFINITION: During acceleration or deceleration, a clunk is heard or felt in the transfer case while in 4LO range only. Review the Symptoms - Transfer Case and perform the necessary inspections.
High/low planetary carrier assemblyInspect for the following conditions: Excessively worn planetary gears The planetary gears loose in the planetary carrier Excessively worn range collar engagement teeth on the carrier Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the high/low planetary if any of the above conditions are found. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Annulus gearInspect the annulus gear to front case fit for excessive looseness. Replace the front case half if the annulus gear is loose. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Range sleeveInspect the range sleeve engagement teeth for excessive wear. Inspect the range sleeve to mainshaft splines for excessive wear. Replace the range sleeve if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.

Transfer Case Clunk in 4LO

Transfer Case Shudder or Binding

CauseCorrection
DEFINITION: A shudder, binding, or a crow-hop while turning, which may cause tire scuffing. Review the Symptoms - Transfer Case and perform the necessary inspections.
Rear differentialIf equipped with a G80 axle, flush and fill with the correct fluid. Refer to Locking Rear Drive Axle Chatters in Turns in Rear Drive Axle - Locking/Limited Slip Rear Axle.

Transfer Case Shudder or Binding

Transfer Case Will Not Shift

CauseCorrection
DEFINITION: While shifting from HI range to LO range, there is gear clashing or no HI range. Or the transfer case will not shift from 2 wheel drive to 4 wheel drive. Review the Symptoms - Transfer Case and perform the necessary inspections.
Shift linkage wornInspect the shift linkage for correct adjustment or for being worn. Refer to Transfer Case Control Lever Replacement and Transfer Case Control Rod Replacement .
Mode shift clashDisassemble the transfer case. Refer to Transfer Case Disassemble in Transfer Case - NVG 261-NP2 Unit Repair. Inspect the synchronizer for being faulty. Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the synchronizer if faulty. Refer to Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Mode blockDisassemble the transfer case. Refer to Transfer Case Disassemble in Transfer Case - NVG 261-NP2 Unit Repair. Inspect the synchronizer for sliding freely on the rear output shaft. Inspect the synchronizer for being faulty. Replace the synchronizer if it is faulty. Refer to Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair. If the symptoms occur during cold temperatures, flush and fill the front axle with synthetic fluid. Refer to Lubricant Level Inspection - Front Drive Axle in Front Drive Axle.
High/low range shift forkInspect the high/low shift fork for the following conditions: The roller on the shift fork for wear or damage Worn or melted range fork pads Cracked or bent shift fork Refer to Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair. Replace the following components if found faulty: The shift fork pads The shift fork Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
High/low range sleeveInspect the high/low range sleeve for the following conditions: Engagement teeth for burrs or damage Sliding freely on the rear output shaft The range sleeve shift fork collar for excessive wear Refer to Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair. Replace the range sleeve if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Input gear needle bearingInspect for the following conditions: Failed needle bearing in the input gear Journal on the rear output shaft for excessive wear or damage Refer to Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair. Replace the bearing if faulty. Replace the mainshaft if damaged.
High/low planetary carrierInspect the high/low planetary engagement teeth for burrs or damage. Refer to Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair. Replace the range sleeve if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.

Transfer Case Will Not Shift

Transfer Case Jumps Out of Gear

CauseCorrection
DEFINITION: Loss of the transfer case drive torque during deceleration, acceleration or under load. Review the Symptoms - Transfer Case and perform the necessary inspections.
Shift linkage wornInspect the shift linkage for correct adjustment or for being worn. Refer to Transfer Case Control Lever Replacement and Transfer Case Control Rod Replacement .
Melted high/low range shift fork padsReplace the high/low range shift fork pads or other damaged components. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Faulty high/low range shift forkInspect the high/low range shift fork for being damaged. Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the shift fork if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Faulty high speed teeth on the range sleeveInspect for the following conditions: The input gear high speed engagement teeth for wear or damage The engagement teeth on the range sleeve for wear or damage Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the range sleeve if the teeth are faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair. Replace the input shaft if the input gear engagement teeth are faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
High/low range shift forkInspect the high/low range shift fork for being faulty. Inspect the range fork shaft for wear. Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the high/low range shift fork if faulty. Refer to Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
High/low planetary carrierInspect the high/low planetary carrier for the following conditions: Low speed engagement teeth worn or damaged Cracked carrier housing Pinion gear bushings worn or out of position Pinion gears broken or damaged teeth Pinion gears seized Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair. Replace the high/low planetary carrier if any of the above conditions are found. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
2/4 Wheel drive synchronizer gearInspect the 2/4 wheel drive synchronizer gear for worn engagement teeth. Replace the synchronizer gear if faulty. Refer to Cleaning and Inspection in Transfer Case - NVG 261-NP2 Unit Repair.

Transfer Case Jumps Out of Gear

Transfer Case Leak Diagnosis

CauseCorrection
DEFINITION: A visible indication of an external fluid leak from the transfer case. Review the Symptoms - Transfer Case and perform the necessary inspections.
Drain plug or fill plug leakInspect for the correct sealer and the correct amount of sealer on the plugs. Install the plugs correctly. Refer to Transfer Case Fluid Replacement .
Access hole plug leakingReplace the access hole plug or seal with RTV sealer.
Vehicle speed sensor leakingRemove the vehicle speed sensor (VSS) and inspect for the following conditions: Cross threaded Cut or damaged O-ring seal VSS over tightened causing deformation in the VSS Refer to Transfer Case Speed Sensor Replacement . Replace the VSS O-ring seal if faulty. Refer to Transfer Case Speed Sensor Replacement . Replace the VSS if faulty. Refer to Transfer Case Speed Sensor Replacement .
Rear output shaft seal leakingInspect for the following conditions: Overfilled or improper transfer case fluid Blocked vent Seal improperly installed, worn, or damaged Seal bore damaged or cracked Rear output shaft bushing for excessive wear Slip yoke seal surface for wear or pitting Repair or replace the following components if found faulty: Adjust or replace the transfer case fluid. Refer to Transfer Case Fluid Replacement . Clean or properly route the vent hose. Replace the slip yoke if the surface could cause leakage. Refer to Propeller Shaft Replacement - One Piece or Propeller Shaft Replacement - Two Piece in Propeller Shaft. Replace the rear bushing if worn. Refer to Transfer Case Output Shaft Seal Replacement - Rear . Replace the rear case half if the seal bore is damaged. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair. Replace the rear output shaft seal. Refer to Transfer Case Output Shaft Seal Replacement - Rear .
Front output shaft seal leakingInspect for the following conditions: Overfilled or improper transfer case fluid Blocked vent Seal improperly installed, worn or damaged Seal bore damaged or cracked Leaking cup plug in the front output shaft Repair or replace the following components if found faulty: Adjust or replace the transfer case fluid. Refer to Transfer Case Fluid Replacement . Clean or properly route the vent hose. Replace the front case half if the seal bore is damaged. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair. Replace the front output shaft seal. Refer to Transfer Case Output Shaft Seal Replacement - Front . Replace the cup plug in the front output shaft if leaking. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Shift shaft detent lever seal leakingReplace the shift shaft detent lever seal. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Leaking at the vent tubeTransfer case overfilled Inspect for the correct transfer case fluid level. Refer to Transfer Case Fluid Replacement . Inspect the transmission fluid level. Refer to Transmission Fluid Checking Procedure in Automatic Transmission - 4L60-E or Transmission Fluid Checking Procedure in Automatic Transmission - 4L80-E or Transmission Fluid Replacement in Manual Transmission - NV 3500 or Transmission Fluid Replacement in Manual Transmission - NV 4500 or Transmission Fluid Replacement in Manual Transmission - ZF S6-650. If the transmission fluid level is low, and the transfer case fluid level is too high, replace the transfer case input shaft seal. Refer to Transfer Case Input Shaft Seal Replacement . Inspect for the following conditions: Seal improperly installed, worn or damaged Seal bore damaged or cracked Input shaft seal surface worn, grooved or damaged Replace damaged or broken vent tube and seal the vent tube with the correct sealer. Refer to Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Transfer case to adapter leakInspect for the following conditions: Loose mounting fasteners Gasket faulty The transfer case input shaft seal leaking The cup bearing in the input shaft leaking Repair or replace the following components if found faulty: Replace the transfer case input shaft seal. Refer to Transfer Case Input Shaft Seal Replacement . Inspect for the following conditions: Seal improperly installed, worn or damaged Seal bore damaged or cracked Input shaft seal surface worn, grooved or damaged Replace the cup bearing in the input shaft if leaking. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair. Repair or replace the loose fasteners. Refer to Transfer Case Adapter Replacement . Replace the transfer adapter case gasket. Refer to Transfer Case Adapter Replacement .
Case leakingInspect for a cracked case or case porosity. Inspect for the wear sleeve missing on the oil pump and the oil pump wearing a hole in the case. Replace the faulty case half. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.
Front case half to rear case half seam leakDisassemble and seal the case halves. Refer to Transfer Case Assemble in Transfer Case - NVG 261-NP2 Unit Repair.

Transfer Case Leak Diagnosis

Removal Procedure

  1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
  2. If the vehicle is a 1500 series, remove the transfer case shield bolts, if equipped.
  3. Remove the transfer case shield, if equipped.
  4. If the vehicle is a 2500 series, remove the transfer case shield screws, if equipped.
  5. Remove the transfer case shield, if equipped.

Installation Procedure

  1. If the vehicle is a 2500 series, position the transfer case shield, if equipped.
  2. Install the transfer case shield screws.
  3. If the vehicle is a 1500 series, position the transfer case shield, if equipped.
  4. Install the transfer case shield bolts, if equipped. Tighten: Tighten the bolts/screws to 20 N.m (15 lb ft).
  5. Lower the vehicle.
IMPORTANTWhen performing the following service procedures, use only hand tools in order to remove and install the fill or drain plugs. Always start the plugs by hand in order to prevent cross threading.
  1. Remove the transfer case shield, if equipped. Refer to «Transfer Case Fluid Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  2. Remove the fill plug.
  3. Remove the drain plug.

Note. Refer to FASTENER NOTICE in Cautions and Notices.

IMPORTANTIf the drain or fill plug have to be replaced, use only aluminum replacement drain plugs. Steel plugs will react with the magnesium of the transfer case.
  1. Install the drain plug. Tighten: Tighten the plug to 20 N.m (15 lb ft).
  2. Fill the transfer case to the bottom of the fill plug hole with the approved transfer case fluid.
  3. Install the fill plug. Tighten: Tighten the plug to 20 N.m (15 lb ft).
  4. Install the transfer case shield, if equipped. Refer to «Transfer Case Fluid Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
  2. Disconnect the speed sensor electrical connector (4).
  3. Remove the speed sensor.
  1. Install the speed sensor. Tighten: Tighten the sensor to 15 N.m (11 lb ft).
  2. Connect the speed sensor electrical connector (4).
  3. Lower the vehicle.
  1. Remove the transfer case shield, if equipped. Refer to «Transfer Case Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  2. Disconnect the gear indicator switch electrical connector (2).
  3. Remove the gear indicator switch.
  1. Install the gear indicator switch. Tighten: Tighten the switch to 27 N.m (20 lb ft).
  2. Connect the gear indicator switch electrical connector (2).
  3. Install the transfer case shield, if equipped. Refer to «Transfer Case Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  1. Remove the transfer case shield, if equipped. Refer to «Transfer Case Fluid Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  2. Remove the front propeller shaft. Refer to «Propeller Shaft Replacement - Front»(ref-197434-S11772894682005101100000) in Propeller Shaft.
  3. Remove the control rod. Refer to «Transfer Case Control Rod Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  4. Lower the vehicle.
  5. Remove the control lever knob by performing the following: Using an adjustable wrench, adjust the wrench to fit the control lever rod just below the knob. With the adjustable wrench touching the control lever knob, gently tap on the adjustable wrench in an upward motion until the knob is separated from the control lever rod.
  6. Remove the transfer case bezel screws.
  7. Remove the transfer case bezel.
  8. Remove the control lever bolts.
  9. Remove the control lever assembly.
  1. Install the control lever assembly.
  2. Install the control lever bolts. Tighten: Tighten the bolts to 12 N.m (106 lb in).
  3. Install the control lever bezel.
  4. Install the control lever bezel screws. Tighten: Tighten the screws to 2 N.m (18 lb in).
  5. Install the control lever knob.
  6. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
  7. Install the shift control rod. Refer to «Transfer Case Control Rod Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  8. Install the front propeller shaft. Refer to «Propeller Shaft Replacement - Front»(ref-197434-S11772894682005101100000) in Propeller Shaft.
  9. Install the transfer case shield, if equipped. Refer to «Transfer Case Fluid Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
IMPORTANTBefore beginning the following service procedure, place a automatic transmission equipped vehicle into the PARK position, place a manual transmission equipped vehicle into FIRST GEAR. Then place the transfer case in the 2 HI position.
  1. Remove the transfer case shield, if equipped. Refer to «Transfer Case Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  2. Remove the front propeller shaft. Refer to «Propeller Shaft Replacement - Front»(ref-197434-S11772894682005101100000) in Propeller Shaft.
  3. Remove the control rod from the control lever.
  4. Remove the control rod from the shift lever.
  5. Remove the control rod.
IMPORTANTBefore installing a NEW control rod, loosen the adjusting bolt on the control rod so it slides with slight resistance. When installing the control rod on the control levers, a snapping sound should be heard or felt upon installation.
  1. Install the control rod onto the control lever first.
  2. Slide the control rod forward.
  3. Install the control rod onto the shift control lever.
  4. Tighten the control rod adjusting bolt. Tighten: Tighten the bolt to 15 N.m (11 lb ft).
  5. Install the front propeller shaft. Refer to «Propeller Shaft Replacement - Front»(ref-197434-S11772894682005101100000) in Propeller Shaft.
  6. Install the transfer case shield, if equipped. Refer to «Transfer Case Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .

Transfer Case Output Shaft Seal Replacement - Front

Tools Required

  1. J 8092 Drive Handle
  2. J 43484 Output Shaft Seal Installer
  1. Remove the transfer case shield, if equipped. Refer to «Transfer Case Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  2. Remove the front propeller shaft. Refer to «Propeller Shaft Replacement - Front»(ref-197434-S11772894682005101100000) in Propeller Shaft.
  3. Insert a flat-tipped screwdriver into the inner race.
  4. Pry the inner race back.
  5. Insert a small pry bar into the inner race.
  6. Remove the inner part of the seal.
  7. Insert a flat-tipped screwdriver or a small pry bar in the space between the outer race of the seal and the transfer case.
  8. Remove the outer part of the seal.
  1. Install the J 43484 (2) to the J 8092 (1).
  2. Install the seal onto the J 43484 (2).
  3. Using the J 43484 (2) and the J 8092 (1), install the seal.
  4. Install the front propeller shaft. Refer to «Propeller Shaft Replacement - Front»(ref-197434-S11772894682005101100000) in Propeller Shaft.
  5. Check the fluid level, add fluid if necessary.
  6. Install the transfer case shield, if equipped. Refer to «Transfer Case Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .

Transfer Case Output Shaft Seal Replacement - Rear

Tools Required

  1. J 37668-A Seal Installer
  2. J 45380 Transfer Case Rear Bushing Remover and Installer
  1. Remove the transfer case shield, if equipped. Refer to «Transfer Case Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  2. Remove the rear propeller shaft. Refer to «Propeller Shaft Replacement - One Piece»(ref-197434-S01803903062005101100000) or «Propeller Shaft Replacement - Two Piece»(ref-197434-S21627766012005101100000) in Propeller Shaft.
  3. Remove the rear output shaft seal.
  4. Inspect the rear output shaft bushing for scoring or wear.
  5. Remove the rear output shaft bushing if required, using the J 45380 . Install the finger section of the J 45380 in front of the bushing. Install the tube and forcing screw to the finger section. Ensure the forcing screw is backed out. Using a wrench on the forcing screw, remove the rear output shaft bushing.
  1. Install a NEW rear output shaft bushing, if required, using the J 45380 . Install the bushing or the finger section of the J 45380 . Install the finger section to the main body of the J 45380 . Position the bushing and tool to the case. Using a hammer and the J 45380 , install the bushing.
  2. Using the J 37668-A , install the rear output shaft seal.
  3. Install the rear propeller shaft. Refer to «Propeller Shaft Replacement - One Piece»(ref-197434-S01803903062005101100000) or «Propeller Shaft Replacement - Two Piece»(ref-197434-S21627766012005101100000) in Propeller Shaft.
  4. Check the fluid level, add fluid if necessary.
  5. Install the transfer case shield, if equipped. Refer to «Transfer Case Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  1. Remove the transfer case shield, if equipped. Refer to «Transfer Case Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  2. Remove the front propeller shaft. Refer to «Propeller Shaft Replacement - Front»(ref-197434-S11772894682005101100000) in Propeller Shaft.
  3. Remove the rear propeller shaft. Refer to «Propeller Shaft Replacement - One Piece»(ref-197434-S01803903062005101100000) or «Propeller Shaft Replacement - Two Piece»(ref-197434-S21627766012005101100000) in Propeller Shaft.
  4. Remove the in-line to engine harness electrical connector (1) from the bracket.
  5. Disconnect the gear indicator switch electrical connector (2).
  6. Disconnect the speed sensor electrical connector (4).
  7. Remove the harness clips (3) from the transfer case.
  8. Reposition the harness.
  9. Remove the vent hose.
  10. Remove the control rod. Refer to «Transfer Case Control Rod Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  11. Support the transmission with a suitable transmission jack stand.
  12. Remove the transmission mount nuts.
  13. Raise the transmission slightly in order to remove the transmission support
  14. Remove the transmission support bolts.
  15. Remove the transmission support.
  16. Support the transfer case with a suitable jack stand.
  17. Remove the transmission mount bolts.
  18. Remove the transmission mount.
  19. Remove the transfer case adapter nuts.
  20. Remove the shift control switch harness bracket.
  21. Separate the transfer case from the transmission by moving the transfer case straight back toward the rear of the vehicle.
  22. Rotate the transfer case so that the front output shaft is above the torsion bar bracket.
  23. Rotate the transfer case (with the input shaft slightly lowered) so that the transfer case is parallel to the torsion bar bracket.
  24. Lower the transfer case.
  1. Raise the transfer case into position (the transfer case should be parallel to the torsion bar bracket).
  2. Rotate the transfer case so that it is in line with the adapter.
  3. Install the transfer case.
  4. Install the shift control switch harness bracket.
  5. Install the transfer case adapter nuts. Tighten: Tighten the nuts to 50 N.m (37 lb ft).
  6. Install the transmission mount.
  7. Install the transmission mount bolts. Tighten: Tighten the bolts to 47 N.m (35 lb ft).
  8. Install the crossmember.
  9. Install the crossmember bolts. Tighten: Tighten the bolts to 70 N.m (52 lb ft).
  10. Lower the transfer case and transmission onto the transmission support.
  11. Install the transmission mount nuts. Tighten: Tighten the nuts to 40 N.m (30 lb ft).
  12. Remove the support from the transfer case.
  13. Remove the transmission jack stand.
  14. Install the control rod. Refer to «Transfer Case Control Rod Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  15. Install the vent hose.
  16. Position the harness.
  17. Install the harness clips (3) to the transfer case.
  18. Connect the speed sensor electrical connector (4).
  19. Connect the gear indicator switch electrical connector (2).
  20. Install the in-line to engine harness electrical connector (1) to the bracket.
  21. Install the rear propeller shaft. Refer to «Propeller Shaft Replacement - One Piece»(ref-197434-S01803903062005101100000) or «Propeller Shaft Replacement - Two Piece»(ref-197434-S21627766012005101100000) in Propeller Shaft.
  22. Install the front propeller shaft. Refer to «Propeller Shaft Replacement - Front»(ref-197434-S11772894682005101100000) in Propeller Shaft.
  23. Check the fluid level. Add fluid if necessary.
  24. Install the transfer case shield, if equipped. Refer to «Transfer Case Speed Sensor Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .

Tools Required

J 42738 Seal Installer

  1. Remove the transfer case. Refer to «Transfer Case Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  2. using a flat-tipped screwdriver, remove the input shaft seal.
  1. Align the transfer case input shaft seal evenly on the input shaft.
  2. Using the J 42738 , install the transfer case input shaft seal.
  3. Install the transfer case. Refer to «Transfer Case Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  4. Check the fluid level. Add fluid of necessary.
  1. Remove the transfer case. Refer to «Transfer Case Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .
  2. Lower the transmission slightly.
  3. Remove the transfer case adapter bolts.
  4. Remove the transfer case adapter.
  5. Remove the transfer case adapter seal.
  6. Remove the transfer case gasket, if necessary.
  1. Install a NEW transfer case adapter seal.
  2. Position the transfer case adapter.
  3. Install the transfer case adapter bolts. Tighten: Tighten the bolts to 50 N.m (37 lb ft).
  4. Install the new transfer case gasket.
  5. Install the transfer case. Refer to «Transfer Case Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/transfer-case/#transfer-case-nvg-261-np2) .

Transfer Case Description and Operation

The New Venture Gear (NVG) 261, RPO NP2 transfer case is a two-speed, part-time with mode shift-on-the-fly capability. It has a chain driven front output shaft and an epicyclical low range planetary arrangement. The NVG 261 transfer case features a four position shift lever control located in the vehicle floor plan. As required, the operator can select 4HI position from 2HI on-the-fly, as described in the owners manual. A dash mounted 4WD lamp continues flashing during shifting, until all criteria have been met and the new mode/range position has been reached. Once the new mode/range position is fully engaged and the front axle disconnect locks in, the dash light 4WD indicator lamp remains ON constantly. Range shifting functions similarly, although it should be limited to speeds 5 km/h (3 mph) or less.

The four manual mode, or range gear positions, of the NVG 261 transfer case are

  1. 2HI - 2 wheel drive high range
  2. 4HI - 4 wheel drive high range, part-time
  3. 4LO - 4 wheel drive low range, 2.72:1 gear ratio reduction
  4. N - Neutral, 4 wheel

When the ignition switch is placed in the run position and the 4WD shift lever is in the 4WD position, the transfer case switch closes, supplying a ground to the axle actuator control circuit. With the ground applied, the logic of the front axle actuator actuates a DC motor to engage the front axle and supply voltage to the axle switch signal circuit. The axle switch signal circuit notifies the powertrain control module (PCM) and the Anti-Lock Brake System that the vehicle is in the 4WD mode. The 4WD indicator is commanded on via a Class 2 serial data signal from the PCM. When the 4WD shift lever is in the 4WD low range position, the transfer case switch closes and supplies a ground on the 4WD low signal circuit. This informs the PCM that the vehicle transfer case is in low range. When the vehicle is in low range, the PCM changes the shift pattern of the automatic transmission.

During normal driving situations, the transfer case can operate in the 2WD mode. The driver may choose to select any of the mode/range gear positions while driving the vehicle. However, the transfer case should not be shifted into or out of 4LO unless the following criteria have been met

  1. The automatic transmission is in neutral or the clutch pedal is depressed.
  2. The vehicle speed is less than 5 km/h (3 mph).

This transfer case also has a neutral position. A shift to the neutral position allows the vehicle to be towed without rotating the transmission output shaft. In the neutral position, the rear propeller shaft rotates the transfer case rear output shaft, in turn rotating the oil pump, providing constant lubrication during towing. Note, this neutral position is a 4WD neutral, meaning the front and rear outputs of the transfer case are engaged as though in 4HI. With a disconnecting front axle, there is no power flow to the front wheels, allowing towing with the front wheels off the ground or flat towing without driveline binding. Again, the transfer case should not be shifted into or out of neutral unless the following criteria have been met

  1. The automatic transmission is in neutral or the clutch pedal is depressed.
  2. The vehicle speed is less than 5 km/h (3 mph).

The NVG 261 transfer case is available in 5 variations, depending on the engine and transmission configurations. The variations allow the transfer case to handle different torque loads. When servicing the transfer case it is important to understand which variation is being serviced because of the difference in parts.

ModelTransmissionInput GearOutput ShaftChain SizeHi/Low PlanetaryApplication
Light Duty (LD)M30 - 4L60E27T Spline32T Spline3/8 X 1.25 in3 PinionK1
Light Duty (LD)MG5 - NV 350032T Spline32T Spline3/8 X 1.25 in3 PinionK1
Heavy Duty 1 (HD1)MT1 - 4L80E MW3 - NV 450032T Spline32T Spline3/8 X 1.5 in6 PinionK2 Non Heavy Duty
Heavy Duty 2 (HD2)MT1 - 4L80E MW3 - NV 450032T Spline32T Spline7/16 X 1.5 in6 PinionK2 Heavy Duty
Super Heavy Duty (SHD)ML6 - ZF S6-650 M74 - Allison29T Spline31T Spline7/16 X 1.5 in6 PinionK3

NVG 261 Variations

The SHD model shares many of the same components, but the increased torque capacity of the SHD requires a double row input bearing and larger diameter rear output shaft, rear output shaft bearing higher capacity, larger rear seal and case halves machined differently.

Some of the changes to the transfer case, that will take place during this model year, include the following

  1. The oil pump suction pipe and screen will change to a 1 piece design.
  2. The 2/4 wheel drive synchronizer gear and drive sprocket sleeve will change to a 1 piece design.

Scheme 5

Scheme 5: 2WD Mode Power Flow
Scheme 5: 2WD Mode Power Flow

The transfer case is shifted by a remote mounted shift lever, which is connected by linkage to the shift lever (9) on the shift detent lever shaft. The shift detent lever shaft rotates the cam shaped shift detent lever (10) and moves the high/low range shift fork (11) or the 2/4 wheel drive mode shift fork (8). Depending on the selected mode or range, the shift forks move either the high/low range sleeve (4) for the high/low range planetary assembly (3) or the synchronizer sleeve (6) for the 2/4 wheel drive mode. In the 2WD mode, the engine power from the transmission (1) is delivered to the input shaft (2). The engagement teeth on the inside of the input shaft (2) are engaged to the outer teeth on the high/low range sleeve (4). The high/low range sleeve (4) is slipped splined to the rear output shaft (5). The engine power flows from the high/low range sleeve (4) to the rear output shaft (5) and is delivered to the rear propeller shaft (7).

Scheme 6

Scheme 6: 4HI Mode Power Flow
Scheme 6: 4HI Mode Power Flow

In the 4HI mode, the engine power from the transmission (1) is delivered to the input shaft (2). The engagement teeth on the inside of the input shaft (2) are engaged to the outer teeth on the high/low range sleeve (3). The high/low range sleeve (3) is slipped splined to the rear output shaft (4). During a shift mode from 2HI to 4HI the cam profile on the shift detent lever (14) pushes the 2/4 wheel drive mode shift fork (9) and the synchronizer sleeve. The sleeve, engaging the synchronizer (5) equalizes the front propeller shaft (12) and rear propeller shaft (7) speeds. Then the sleeve engages to the 2/4 wheel drive synchronizer gear (8), which is splined to the drive sprocket (6). The engine power flow for driving the front propeller shaft (12), now travels from the rear output shaft (4) to the synchronizer hub, which is splined to the rear output shaft (4). The power flows from the synchronizer hub to the sleeve and then to 2/4 wheel drive synchronizer gear (8). The power flow is transmitted by a chain (10) to the driven sprocket on the front output shaft (11) and to the front propeller shaft (12). The front and rear propeller shafts are being driven at equal RPMs, therefore giving a four wheel drive mode. This mode should only be used for extra traction. Using this mode on dry pavement causes tire scuffing when turning.

Scheme 7

Scheme 7: 4LO Mode Power Flow
Scheme 7: 4LO Mode Power Flow

During range shift request to 4LO, a separate cam profile on the same shift detent lever (12) moves the high/low shift fork (13). The high/low shift fork (13) moves the high/low range sleeve (6) rearward. The high/low range sleeve (6) outer teeth disengage from the input shaft (2) high-speed teeth. The high/low range sleeve (6) outer teeth then engage in the high/low planetary carrier teeth (5). The power flow is now from the transmission (1), to the planetary teeth on the input shaft (2), to the planetary gears (3) in the carrier. Rotating the planetary gears (3), which are engaged in the annulus gear (4), rotates the planetary carrier. The planetary carrier delivers the power to the high/low range sleeve (6). The high/low range sleeve (6) then drives the rear output shaft (7), providing a 2.72:1 gear ratio reduction to the rear output shaft (7). The 2/4 wheel drive synchronizer (8) is still engaged to drive the drive sprocket (9), as in the 4HI position, providing the engine power to the rear propeller shaft (10) and to the front propeller shaft (11).

Neutral Mode Power Flow

Shifting to the neutral position, the high/low range sleeve is centered between the input shaft and the high/low planetary carrier. The high/low range sleeve is not engaged with either the input shaft or the high/low planetary carrier teeth. The 2/4 wheel drive synchronizer is in the 4HI mode position.

Special Tools

Special Tools Illustration Tool Number/Description J 8092 Driver Handle J 37668-A Seal Installer J 42738 Seal Installer J 43484 Output Shaft Seal Installer J 45380 Transfer Case Rear Bushing Remover and Installer

Scheme 8

Scheme 8: Special Tools
Scheme 8: Special Tools

Scheme 9

Scheme 9
Scheme 9

Scheme 10

Scheme 10
Scheme 10

Scheme 11

Scheme 11
Scheme 11

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