How to change a transfer case encoder motor.

lovesrugers

Original poster
Member
Jan 25, 2012
30
Thanks to all the great help this site has been I decided I needed to give back. Anyway since I needed to change out my encoder motor on my 2002 Bravada I figured I might as well document the process.

Tools needed

Flat bladed screwdriver
Socket set, mainly 13 mm socket and 6 inch extension
Torque wrench
Vice grips


Step 1:
Raise and support your vehicle. I just used ramps placed on both the driver side wheels. This gave me enough room to get under and access everything. A lift would be ideal for doing this job but ramps or a jack will get it done. Edited to add in if you have a Trailblazer or Envoy make sure your selector switch is in 2 Hi before starting.

encoder1.jpg


Step 2:
Locate your encoder motor. It is located on the side of the transfer case which is located about under the drivers seat. Once you locate the motor look for the wire coming off of it. Follow this wire up to the top of the transfer case. There you will find where it plugs in at. Undo this connection. I found the easiest way to do this was to lay under the vehicle with your feet going towards the engine and your chest and arms under the transfer case. From there reach your left arm up one side of the transfer case and your right arm up the other side. In order to make disconnecting the harness easier I used a flat bladed screwdriver to release the catch. You will have to do this by feel because you really can't see the connection. Once this is done you can pull the wire down and out of the way.

Now you are ready to remove the encoder motor bolts. To do this I used a socket wrench with a six inch extension and a 13mm socket. I started off with the top most inaccessible bolt. When removing the bolts I placed them on the ground in a way so that the same bolt would go back into the same hole. Once you have all four bolts out you can remove the encoder motor. You may have to give it a wack with your hand to free it up but from there it pulls straight off. Here is a view of the encoder motor on the transfer case and removed.


encoder2.jpg


encoder3.jpg


Step 4:
Here is a view of the old and new encoder motor. Notice that the old motor on the left has sleeves in the 10 o'clock and 4 o'clock bolt holes. These locating sleeves need to be removed and installed in the new motor. I did this by using a set of vice grips to gently squeeze the sleeves and then pull them out. From there you can install them into the new motor. Once this is done clean the mating surfaces on the transfer case and encoder motor and install the new motor. Fitting the new motor onto the shaft coming out of the case is the hardest part. It is pretty much a matter of trial and error but once everything lines up it will slide onto the shaft. Once the motor is installed onto the shaft reinstall the four bolts and torque them down to 12 ft lbs. The final step is to reconnect the wire harness from the motor to the vehicle. Before doing this I used some electrical contact cleaner on the vehicle side of the harness and then applied dielectric grease to the connectors.


encoder4.jpg


There you have it. Time to do this job took me about an hour including set-up and clean up. Note I did this job on an Oldsmobile Bravada. It uses a different transfer case than the Envoy and Trailblazer and a different wiring connector, 5 pins vs 7 pins. Other than that the job should be pretty similar.

Jerry
 
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DJones

Member
Jan 21, 2012
701
St. Petersburg, Florida
When I swap out my transfer case, I'll be using the motor I have already, because the used one is very well used. Nice write-up :thumbsup:
 

Jman423

Administrator
Mar 24, 2014
1,874
United States
Please provide the following information:

Summary:

Vehicle:
Difficulty:
Estimated Time:
Part Numbers:
Cost:
 

lovesrugers

Original poster
Member
Jan 25, 2012
30
Looks like I can't edit my first post so here is the requested information.

Summary:How to change a transfer case encoder motor, Bravada, Trailblazer, Envoy, Raineer.
Vehicle:2002 Oldsmobile Bravada and similar
Difficulty:Easy
Estimated Time:45 minutes to 1 hour.
Part Numbers:Varies by make but for the Bravada, Dorman 600904.
Cost:$125-$215 depending on model and if using re manufactured parts.

Let me know if you need this cleaned up some more or not.

Jerry
 

Tinman1

Member
May 19, 2013
2
lovesrugers said:
Thanks to all the great help this site has been I decided I needed to give back. Anyway since I needed to change out my encoder motor on my 2002 Bravada I figured I might as well document the process.

Tools needed

Flat bladed screwdriver
Socket set, mainly 13 mm socket and 6 inch extension
Torque wrench
Vice grips


Step 1:
Raise and support your vehicle. I just used ramps placed on both the driver side wheels. This gave me enough room to get under and access everything. A lift would be ideal for doing this job but ramps or a jack will get it done. Edited to add in if you have a Trailblazer or Envoy make sure your selector switch is in 2 Hi before starting.

encoder1.jpg


Step 2:
Locate your encoder motor. It is located on the side of the transfer case which is located about under the drivers seat. Once you locate the motor look for the wire coming off of it. Follow this wire up to the top of the transfer case. There you will find where it plugs in at. Undo this connection. I found the easiest way to do this was to lay under the vehicle with your feet going towards the engine and your chest and arms under the transfer case. From there reach your left arm up one side of the transfer case and your right arm up the other side. In order to make disconnecting the harness easier I used a flat bladed screwdriver to release the catch. You will have to do this by feel because you really can't see the connection. Once this is done you can pull the wire down and out of the way.

Now you are ready to remove the encoder motor bolts. To do this I used a socket wrench with a six inch extension and a 13mm socket. I started off with the top most inaccessible bolt. When removing the bolts I placed them on the ground in a way so that the same bolt would go back into the same hole. Once you have all four bolts out you can remove the encoder motor. You may have to give it a wack with your hand to free it up but from there it pulls straight off. Here is a view of the encoder motor on the transfer case and removed.


encoder2.jpg


encoder3.jpg


Step 4:
Here is a view of the old and new encoder motor. Notice that the old motor on the left has sleeves in the 10 o'clock and 4 o'clock bolt holes. These locating sleeves need to be removed and installed in the new motor. I did this by using a set of vice grips to gently squeeze the sleeves and then pull them out. From there you can install them into the new motor. Once this is done clean the mating surfaces on the transfer case and encoder motor and install the new motor. Fitting the new motor onto the shaft coming out of the case is the hardest part. It is pretty much a matter of trial and error but once everything lines up it will slide onto the shaft. Once the motor is installed onto the shaft reinstall the four bolts and torque them down to 12 ft lbs. The final step is to reconnect the wire harness from the motor to the vehicle. Before doing this I used some electrical contact cleaner on the vehicle side of the harness and then applied dielectric grease to the connectors.


encoder4.jpg


There you have it. Time to do this job took me about an hour including set-up and clean up. Note I did this job on an Oldsmobile Bravada. It uses a different transfer case than the Envoy and Trailblazer and a different wiring connector, 5 pins vs 7 pins. Other than that the job should be pretty similar.

Jerry

Does the transfer case have to be reprogramed after this?
 

lovesrugers

Original poster
Member
Jan 25, 2012
30
Nope, I believe that only needs to happen if you replace the encoder ring. The new encoder motor should be a plug and play part.

Jerry
 

Tinman1

Member
May 19, 2013
2
lovesrugers said:
Nope, I believe that only needs to happen if you replace the encoder ring. The new encoder motor should be a plug and play part.

Jerry

Jerry,
Thanks!
 

w.poole

Member
Jun 6, 2013
2
lovesrugers said:
Nope, I believe that only needs to happen if you replace the encoder ring. The new encoder motor should be a plug and play part.

Jerry

Hi Jerry, Thanks for the great write up!

I have an 02 Bravada that is experiencing binding in slow turns. I jacked up all four corners and unplugged the encoder motor and I am still getting power to the front wheels. I read in another forum that if you unplug the encoder motor it should be like a 2wd vehicle.

If I swap out the encoder motor, do I need to return the TC case to 2wd mode? I'm not sure how the engage mechanism works. I have an 04 bravada that acts completely different (its working correctly) when jacked up in all corners it pulses the drive to the front axle and you can hear the encoder motor working. On my 02, it's silent so I am assuming it has failed.

Any thoughts you have are appreciated!

Thanks!

Wayne
 

lovesrugers

Original poster
Member
Jan 25, 2012
30
Wayne, first off when was the last time you changed your transfer case fluid? This is supposed to be done every 50k miles and will cause the same binding as a stuck encoder motor.

As far as the unplug the motor and see if it goes into 2wd I don't know. I do know that a quick test it to just go ahead and take the encoder motor off. At this point the transfer case should go to 2wd mode by itself. You can then rotate the encoder shaft with the proper wrench to check for proper awd engagement. If after you remove your motor and you are still stuck in awd even with manually moving the shaft to the disengagement position then your transfer case clutch pack may be fried or just stuck together. Once again if it is just stuck together try changing the fluid a couple of times. This has worked for many people and is actually the suggested fix according to a TSB on our vehicles.

Hopefully this helps you out some.

Jerry
 

w.poole

Member
Jun 6, 2013
2
Hi Jerry,

Thanks for the tips. Yes, I changed out my TC fluid first, since that was probably the cheapest option. I have an 04 that showed a "pulsing" symptom when turning and that fixed the problem also!

I swapped out the encoder motor and that fixed the problem. I did try unhooking it before replacing it, but that left the motor engaged, so I'm not sure what the expected result should be in that case.

Regardless, we are back on the road.

Cheers!




lovesrugers said:
Wayne, first off when was the last time you changed your transfer case fluid? This is supposed to be done every 50k miles and will cause the same binding as a stuck encoder motor.

As far as the unplug the motor and see if it goes into 2wd I don't know. I do know that a quick test it to just go ahead and take the encoder motor off. At this point the transfer case should go to 2wd mode by itself. You can then rotate the encoder shaft with the proper wrench to check for proper awd engagement. If after you remove your motor and you are still stuck in awd even with manually moving the shaft to the disengagement position then your transfer case clutch pack may be fried or just stuck together. Once again if it is just stuck together try changing the fluid a couple of times. This has worked for many people and is actually the suggested fix according to a TSB on our vehicles.

Hopefully this helps you out some.

Jerry
 

joller

Member
Mar 25, 2014
4
after viewing your thread on the tcem replacement, the only thing i have to question before i do mine, is what mode of operation was your transfer case stuck in before pulling encoder motor off? my 2003 tb switch light is stuck in A4wd. therefore i am thinking that encoder motor has switched the transfer case gear to this and is now not working to go back to 2hi. i am unsure of where i am taking this but i will continue. i saw the gear coming out of transfer case. i could not tell, but does this gear with the splines have a certain way to be fitted with the new motor splines before replacement? does it have to be rotated to a certain position to receive new part?
 

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