Transfer Case - Diagnosis Chevrolet Chevy Express H2500

Diagnostic Starting Point - Transfer Case

Note. For additional information on transfer case, refer to SERVICING - T/C and REMOVAL & INSTALLATION - T/C .

Begin the system diagnosis by reviewing the Symptoms - Transfer Case . The Symptoms - Transfer Case will provide the following information

1. The required visual/physical inspections.
2. The list of symptoms.

Strategy Based Diagnostics

Review the system operation in order to familiarize yourself with the system functions. Refer to TRANSFER CASE DESCRIPTION & OPERATION .

Visual/Physical Inspection

1. Inspect the easily accessible or visible system components for obvious damage, or for conditions which could cause the symptom.
2. Inspect the transfer case for the proper fluid. Refer to «DRAINING & REFILLING»(/chevrolet/chevy-express-h2500/2003-2003/remont/transfer-case/#transfer-case-servicing__draining-refilling) .

Symptom List

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

1. «Transfer Case Popping Noise»(/chevrolet/chevy-express-h2500/2003-2003/remont/transfer-case/#transfer-case-diagnosis)
2. «Transfer Case Whine or Rumble Noise»(/chevrolet/chevy-express-h2500/2003-2003/remont/transfer-case/#transfer-case-diagnosis)
3. «Transfer Case Growl or Grinding Noise»(/chevrolet/chevy-express-h2500/2003-2003/remont/transfer-case/#transfer-case-diagnosis)
4. «Transfer Case Clunk during Acceleration and Deceleration»(/chevrolet/chevy-express-h2500/2003-2003/remont/transfer-case/#transfer-case-diagnosis)
5. «Transfer Case No Front Drive»(/chevrolet/chevy-express-h2500/2003-2003/remont/transfer-case/#transfer-case-diagnosis)
6. «Transfer Case Leak Diagnosis»(/chevrolet/chevy-express-h2500/2003-2003/remont/transfer-case/#transfer-case-diagnosis)

Scheme 22

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Scheme 27

Scheme 28

Transfer Case Viscous Coupling Test

Tools Required

J 45382 Transfer Case Tester

To determine if the viscous coupling is operating correctly, use the following test procedure. Testing the viscous coupling operation by removing a propeller shaft and driving the vehicle will cause the viscous coupling to fail. The test will determine if the viscous coupling is faulty from a totally locked up failure, or if the viscous coupling fluid has leaked out from being severely humped.

Important: The Viscous Coupling Test is very sensitive to the temperature of the transfer case. If the transfer case is very hot, the time to turn will be faster. If the transfer case is cold, the time to turn will be slower.

Scheme 29

1. Operate the vehicle for 24 km (15 mi), or until normal operating temperatures are reached.
2. Set the parking brakes for the rear wheels.
3. Position the transmission in NEUTRAL.
4. Raise the vehicle.
5. Remove the front propeller shaft. Refer to «PROPELLER SHAFT REPLACEMENT - FRONT»(/chevrolet/chevy-express-h2500/2003-2003/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) .
6. Install the J 45382 into the transfer case front output shaft.
7. Using a torque wrench at 11 N.m (100 lb in) on the J 45382 , turn the front output shaft 90 degrees.
8. Note the length of time it takes to turn the front output shaft the 90 degrees. If the front output shaft turns slow, and takes at least 10 seconds, the viscous coupling is operating correctly. If the front output shaft will not turn, the viscous coupling or the planetary carrier assembly could be locked-up. If the front output shaft turns easily, and the 11 N.m (100 lb in) cannot be obtained, the viscous coupling is faulty.

See also:
• SERVICING - T/C
• REMOVAL & INSTALLATION - T/C
• DRAINING & REFILLING
• PROPELLER SHAFT REPLACEMENT - FRONT
• Symptoms - Transfer Case