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Gary
Gary, Technician
Category: Car
Satisfied Customers: 11414
Experience:  GM master tech for 15 years/ASE master tech for 20 years
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2000 BRAVADA TRANSFER CASE STAY ENGAGE ENCODER.MODULE AND OIL

Customer Question

2000 BRAVADA TRANSFER CASE STAY ENGAGE ENCODER.MODULE AND OIL BEEN CHANGE GM OIL TOO SEEM LIKE CLUTCHS WON'T DISENGAGE
Submitted: 4 years ago.
Category: Car
Expert:  Gary replied 4 years ago.

how do you know it stays engaged?does it show it going into 2 wheel on the switch?

Customer: replied 4 years ago.
FRONT WHEELS STAY INGAGED. PULL ENCODER MOTOR AND SHIFTED BY HAND. FRONT SHAFT WONT RELEASE.
Expert:  Gary replied 4 years ago.
ok so the front axle stays engaged even when the transfer case is shifter into 2wd is this correct?sorry for the 20 questions i just want to give you the best possible answer i can
Customer: replied 4 years ago.
YES
Expert:  Gary replied 4 years ago.
ok get under the truck and get to the transfer case and find the ball switch there right above the encoder motor..un plug that and and run the truck and see if then the front diff unlocks..ok?let me know if it does..here is a picture of it
Customer: replied 4 years ago.
THIS CASE DOESNT HAVE THIS SET .THE FRONT AXLE DOESNT HAVE A SHIFT MOTOR.
Expert:  Gary replied 4 years ago.
so this is a selectable 4WD?auto?any switches to activate the 4WD?autoallwheel drive?
Customer: replied 4 years ago.

AUTO ALL WHEEL DRIVE

Expert:  Gary replied 4 years ago.

is your problem that the drive shaft from the case to front diff is always turning?what is your complaint?noise?ect...?

Customer: replied 4 years ago.
WHEEL HOPPING AND ENCODER MOTOR KEEPS BURNING OUT
Expert:  Gary replied 4 years ago.
ok.what fluid did you put in the case?
Customer: replied 4 years ago.
AUTO TRAC II
Expert:  Gary replied 4 years ago.
ok there is a bulletin for this complaint ..and yes auto trac was correct but there is a procedure you have to follow..here is the bulletin and please follow the procedure..Subject:
Transfer Case Shudder (Flush and Replace Transfer Case Fluid)

 

Models:
1999-2005 Chevrolet Astro (AWD)
1999-2005 GMC Safari (AWD)
1999-2001 Oldsmobile Bravada

 

with All-Wheel Drive (NV 136) Transfer Case (RPO NP4)

Supercede:

This bulletin is being revised to update the correction information. Please discard Corporate Bulletin Number 99-04-21-005D (Section 04 - Driveline/Axle).

Condition

Some customers may comment on a vibration (shudder) during tight turning maneuvers on dry pavement at vehicle speeds less than 8 km/h (5 mph).

Cause

This condition may be caused by a slip-stick of the clutch plates in the transfer case clutch pack. On 1999 to 2002 models, the preload that is designed into the clutch pack may contribute to the condition. In addition, contamination of the fluid may interfere with the friction modifiers.

Correction

Flush and replace the transfer case fluid on affected vehicles using the following procedure and the part number listed below.

Perform the following diagnosis prior to flushing and replacing the transfer case fluid in order to properly identify the shudder.

Diagnosis

1.Verify the shudder in the vehicle. The vehicle needs to be at operating temperature (driven at least 8 km (5 mi) for proper diagnosis. After the vehicle is at operating temperature, drive in a tight circle just short of steering wheel lock, at a speed less than 8 km/h (5 mph) in order to identify the shudder.

 

2.Identify what rear axle type the vehicle has.

 

^If the vehicle has a standard rear axle, then proceed to step 3.

 

^If the vehicle has a locking rear axle, remove the front propeller shaft. Refer to the Propeller Shaft subsection in the Service Manual. Drive the vehicle as outlined in step 1.

 

^If the shudder goes away, install the front propeller shaft and proceed to step 3. Refer to the Propeller Shaft subsection in the Service Manual.

 

^If the shudder does not go away, the locking rear axle may be the cause. Evaluate the condition using diagnostic information in the appropriate Service Manual.

 

^Install the front propeller shaft. Refer to the Propeller Shaft subsection in the Service Manual.

 

3.Flush the transfer case with the blue colored fluid (AUTO-TRAK II) using the procedure and part number listed below. Perform the flush procedure even if the transfer case contains the blue colored AUTO-TRAK II fluid in order to remove any possible contaminants. The AUTO-TRAK II fluid contains an improved friction modifier that should correct the slip-stick condition. Refer to the Transfer Case subsection in the Service Manual for information on draining and filling the transfer case.

 

Flush Procedure

Important: Refer to Corporate Bulletin Number 99-04-21-001 dated April 1999, for important information on removing the transfer case drain and fill plugs.

 

1.Drain the transfer case fluid.

 

2.Refill the transfer case with 2L (2 qts) of new fluid, P/N 12378508 (Canadian P/N 10953626).

 

3.After refilling the transfer case, drive the vehicle a minimum of 8 km (5 mi).

 

4.With the transfer case at operating temperature, drain the transfer case fluid again.

 

5.Refill the transfer case with new fluid.

 

Important: The vehicle may require approximately 160 km (100 miles) of driving before the condition is completely corrected.

 

6.If this procedure does not correct the shudder condition, please call the Technical Assistance Center for further instructions and review PIP3012D or newer.

 

Customer: replied 4 years ago.

HAVE ALREADY DONE THIS PER SERVICE BULLETIN ABOVE - NO CHANGE

Expert:  Gary replied 4 years ago.
if you followed it just like they said to do and it is still doing it.then the clutches inside are failing and causing this problem.that unit needs to come out and apart.more than likely the clutches are worn and chattering
Customer: replied 4 years ago.
HAVE ALREADY PULLED IT APART AND THE CLUTCHES AND STEELS LOOK GOOD!
Expert:  Gary replied 4 years ago.
yes they can look good but did you set up the clutch pak?here is how its done


  1. With the clutch drum full and on the main shaft, position the rear section of the main shaft through the hole of a flat fixture or surface.
    • The fixture must be a machined flat fixture or surface.
    • The hole in the fixture should be large enough to allow the rear of the shaft to fit through the hole with the bottom of the clutch drum sprocket flange resting on the flat surface.
    • Ensure the clutch drum has all the inner clutch plates and outer separator plates required for the clutch drum.
    • The NV 136 transfer case has eight clutch and separator plates.
    • The NV 246 transfer case has ten clutch and separator plates.
    • Ensure the existing clutch plate shim(s) are not installed in the clutch drum.

  1. Using a micrometer, measure the thickness of the machined flat disk (3).
  2. Record the measurement.
  3. Take two additional disk measurements at 120°apart from each other and record the measurements.
  4. Take the average the three recorded measurements. Use this average as the thickness measurement of the machined flat disk.
  5. Position a disk (3) that will fit over the top of the main shaft and rest on the top inner clutch plate.
    • The disk (3) being used must be machined round and flat to be used for an accurate measurement.
    • Ensure the flat disk is resting on the top inner clutch plate only, and not resting on the inner drum.
    • Ensure the bottom of the mainshaft clutch drum sprocket flange is resting on the flat surface (4).
  1. Their should be a small gap between the flat disk (3) and the clutch outer drum (5).
  2. Position 100 pounds (45.4 Kilograms) of weight disks (1) and (2) on top of the flat disk (3).
    • The weight being used may vary no more than plus or minus 10%.
    • The disk weight(s) do not need to be machined round and flat.

  1. Using a height gage, measure the from the top of the flat machined disk (1) to the flat machined fixture surface (2).
  2. Record the measurement.
  3. Take two additional measurements at 120* apart from each other and record the measurements.
  4. Take the average of the three recorder measurements. Use this average as the distance measurement from the top of the flat machined disk to the flat machined fixture surface.
  5. Subtract the (flat disk thickness) measurement from the (top of the flat machined disk to the flat machined fixture surface) measurement. (Top of the flat machined disk to the flat machined fixture surface measurement) - (flat disk thickness measurement). The remaining distance is the distance gap between the top of the outer clutch drum and the inner clutch plate.
  6. The gap size needs to be between 4.025 to 4.035 inch (102.235 to 102.489 millimeters) .

  1. Add shims to the top of the inner clutch plate as necessary to increase the gap to the required tolerance.
  2. Repeat the procedure with the shims installed to ensure the tolerance is obtained.

 

Customer: replied 4 years ago.
WE ARE GOING TO TRY THIS. IF IT DOESN'T CORRECT THE PROBLEM, IS THERE A WAY WE CAN RECONNECT WITH YOU LATER?
Expert:  Gary replied 4 years ago.
yes just repost threw here.and print out or save the information i sent you..the pictures time out quickly..
Customer: replied 4 years ago.
AT THIS TIME...DO I ACCEPT OR JUST EXIT OUT?
Expert:  Gary replied 4 years ago.
you can accept if you are satisfied..and you can get me right back threw this post either way..if you accept now or not..thats your call if you are satisfied..it doesn't matter to me i just want your truck fixed

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Gary
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GM master tech for 15 years/ASE master tech for 20 years