Hummer H2. Manual - part 2661

Drain plug or fill 
plug leak

1. Inspect for the correct sealer and the correct amount of sealer on the plugs.  

2. Install the plugs correctly. Refer to Transfer Case Fluid Replacement .  

Vehicle speed 
sensor leaking

1. Remove the vehicle speed sensor (VSS) and inspect for the following 

conditions: 

z

Cross threaded  

z

Cut or damaged O-ring seal  

z

VSS over tightened causing deformation in the VSS 

Refer to Transfer Case Speed Sensor Replacement . 

2. Replace the VSS O-ring seal if it is faulty. Refer to Transfer Case Speed 

Sensor Replacement .  

3. Replace the VSS if it is faulty. Refer to Transfer Case Speed Sensor 

Replacement .  

Rear output shaft 
seal leaking

1. Inspect for the following conditions: 

z

Overfilled or improper transfer case fluid  

z

Blocked vent  

z

Seal improperly installed, worn, or damaged  

z

Seal bore damaged or cracked  

z

Rear output shaft bushing for excessive wear  

z

Slip yoke seal surface for wear or pitting  

2. Repair or replace the following components if found faulty: 

z

Adjust or replace the transfer case fluid. Refer to Transfer Case Fluid 
Replacement .  

z

Clean, or properly route the vent hose.  

z

Replace the slip yoke if the surface could cause leakage. Refer to 
Propeller Shaft Replacement - Rear in Propeller Shaft.  

z

Replace the rear case half if the bushing is worn. Refer to Transfer 
Case Disassemble and Transfer Case Assemble .  

z

Replace the rear case half if the seal bore is damaged. Refer to 
Transfer Case Disassemble and Transfer Case Assemble .  

z

Replace the rear output shaft seal. Refer to Transfer Case Output 
Shaft Seal Replacement - Rear .  

Front output shaft 
seal leaking

1. Inspect for the following conditions: 

z

Overfilled or improper transfer case fluid  

z

Blocked vent  

z

Seal improperly installed, worn, or damaged  

z

Seal bore damaged or cracked  

2. Repair or replace the following components if found faulty: 

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Transfer Case - BW 4484 - Hummer H2

  

z

Adjust or replace the transfer case fluid. Refer to Transfer Case Fluid 
Replacement .  

z

Clean or properly route the vent hose.  

z

Replace the front case half if the seal bore is damaged. Refer to 
Transfer Case Disassemble and Transfer Case Assemble .  

z

Replace the front output shaft seal. Refer to Transfer Case Output 
Shaft Seal Replacement - Front .  

Shift shaft detent 
seal leaking

1. Remove the encoder motor and inspect for the shift detent seal leaking.  

2. Replace the shift shaft detent seal. Refer to Transfer Case Disassemble and 

Transfer Case Assemble .  

Leaking at the vent

z

Transfer case overfilled 

1. Inspect for the correct transfer case fluid level. Refer to Transfer Case 

Fluid Replacement .  

2. Inspect the transmission fluid level. Refer to Transmission Fluid 

Checking Procedure in Automatic Transmission - 4L60-E.  

3. 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 .  

4. Inspect for the following conditions: 

z

Seal improperly installed, worn, or damaged  

z

Seal bore damaged or cracked  

z

Input shaft seal surface worn, grooved, or damaged  

z

Seal the vent with the correct sealer if it is leaking at the case. Refer to 
Transfer Case Assemble .  

Transfer case to 
adapter leak

1. Inspect for the following conditions: 

z

Loose mounting fasteners  

z

Gasket or sealant faulty  

z

The transfer case input shaft seal leaking  

2. Repair or replace the following components if found faulty: 

z

Replace the transfer case input shaft seal. Refer to Transfer Case 
Input Shaft Seal Replacement .  

z

Inspect for the following conditions: 

„

Seal improperly installed, worn, or damaged  

„

Seal bore damaged or cracked  

„

Input shaft seal surface worn, grooved, or damaged  

z

Repair or replace the loose fasteners. Refer to Transfer Case Adapter 
Replacement .  

z

Replace the transfer case gasket or sealer. Refer to Transfer Case 
Adapter Replacement .  

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Transfer Case - BW 4484 - Hummer H2

  

REPAIR INSTRUCTIONS 

TRANSFER CASE SHIFT CONTROL MODULE REPLACEMENT 

Removal Procedure 

Fig. 7: Transfer Case Shift Control Module 
Courtesy of GENERAL MOTORS CORP.

Front case half to 
rear case half seam 
leak

Disassemble and seal the case halves again. Refer to Transfer Case Disassemble 
and Transfer Case Assemble .

Case leaking

1. Inspect for a cracked case or case porosity.  

2. Replace the faulty case half. Refer to Transfer Case Disassemble and 

Transfer Case Assemble .  

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Transfer Case - BW 4484 - Hummer H2

  

1. Remove the knee bolster. Refer to Trim Panel Replacement - Knee Bolster in Instrument Panel, 

Gauges, and Console.  

2. Disconnect the shift control module electrical connectors.  

3. Reposition the harness.  

4. Remove the module from the vehicle.  

Installation Procedure 

Fig. 8: Transfer Case Shift Control Module 
Courtesy of GENERAL MOTORS CORP. 

1. Install the shift control module to the vehicle.  

2. Connect the shift control module electrical connectors.  

3. Install the knee bolster. Refer to Trim Panel Replacement - Knee Bolster in Instrument Panel, Gauges, 

and Console.  

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Transfer Case - BW 4484 - Hummer H2