NEED HELP Manually Adjust Transfer Case Position?

[AC75TB07]

Hey,

I just got a new shift motor in to sort my 4x4 problems but the new motor is in one position while the TC is in another... How do I adjust the position of the TC (shaft?) so I can get the new motor in alignment to bolt in place?

Thanks...

 

[TollKeeper]

If I am remembering correctly, you take a wrench that fits the shaft perfectly (NO SLOP/PLAY), and turn it.

 

[AC75TB07]

Won't that damage the little spines?

Side thought: If I were to plug-in the new motor but not bolt it to the TC would it move to allow alignment with whatever setting the TC is currently in?

 

[TollKeeper]

You have a splined shaft? I thought you could use a 12 point socket on those..

@Mooseman or @mrrsm might have better info.

 

[AC75TB07]

Well it looks like this... (not my pic)

 

[Mooseman]

The motor can only go on that shaft one way. Put it on and if the bolt holes aren't lined up, turn the motor until it is. The hears inside can take it.

 

[TJBaker57]

Well it looks like this... (not my pic)

View attachment 109370

That looks very familiar! It's my 2002

Where is the notch pointed on your transfer case shaft now?

I don't know if you can turn that motor by hand, there is a lot of gear reduction in there. GM suggests turning the motor with a special harness and 9 volt battery. I have read where some folks have opened up the motor and then turn it to the desired position. I have yet to disassemble that end if one of these. Someday.

 

[budwich]

I used a tool battery (12v) to run the motor BUT you need to be careful because there is NO stops for the motor and it will spin and potentially cause damage to the ring sensor. The motor "spin" is "guarded" by the physical stops inherent in the transfer case and not anything directly related to the motor although there is a sensor to indicate "relative" position... it is related to the physical stops. You should be able to turn the shaft on the transfer case. What was the original problem that led you down this path? Do you actually know what state your transfer case is currently in?

 

[TJBaker57]

used a tool battery (12v) to run the motor

Additionally, the electric brake inside the motor should be released before trying to 'run' the motor.

 

[AC75TB07]

The motor can only go on that shaft one way. Put it on and if the bolt holes aren't lined up, turn the motor until it is. The hears inside can take it.

Really, it won't strip out or nothing? That's why I wouldn't force it...

That looks very familiar! It's my 2002

Where is the notch pointed on your transfer case shaft now?

I don't know if you can turn that motor by hand, there is a lot of gear reduction in there. GM suggests turning the motor with a special harness and 9 volt battery. I have read where some folks have opened up the motor and then turn it to the desired position. I have yet to disassemble that end if one of these. Someday.

Thanks for the photo evidence! Been very useful.

Additionally, the electric brake inside the motor should be released before trying to 'run' the motor.

How does one go about doing that?

I used a tool battery (12v) to run the motor BUT you need to be careful because there is NO stops for the motor and it will spin and potentially cause damage to the ring sensor. The motor "spin" is "guarded" by the physical stops inherent in the transfer case and not anything directly related to the motor although there is a sensor to indicate "relative" position... it is related to the physical stops. You should be able to turn the shaft on the transfer case. What was the original problem that led you down this path? Do you actually know what state your transfer case is currently in?

It's in regular RWD right now. The problem originally was the 4x4 service light came on and I wasn't able to shift into any function. A couple times it sorta tried to do something after pulling the ATC fuse, and once unexpectedly it went into 4Hi. Finally everything shut down and the switch only illuminated at startup. I took it to the dealer to get the codes checked and the result was I needed a new TC motor. I got a new one but was having trouble getting it into alignment, worrying that I may wreck something if I put any kind of force on it.

 

[budwich]

Additionally, the electric brake inside the motor should be released before trying to 'run' the motor.

I should have mentioned that. of course you need to provide power ALSO to the brake lead to energize it.

 

[budwich]

It's in regular RWD right now. The problem originally was the 4x4 service light came on and I wasn't able to shift into any function. A couple times it sorta tried to do something after pulling the ATC fuse, and once unexpectedly it went into 4Hi. Finally everything shut down and the switch only illuminated at startup. I took it to the dealer to get the codes checked and the result was I needed a new TC motor. I got a new one but was having trouble getting it into alignment, worrying that I may wreck something if I put any kind of force on it.

Not sure that you can say that directly. Why? I think that the system tries to "guess" what it "thinks" the state of the drive system is in. The light indicator is not directly tied to this state... it is a "fall back" indicator based on where its was coming from and where it was trying to get to. The physical transfer case could be "anywhere" depending on what the failure was./ is. I think TJbaker57 asked about the current "offset" position on the shaft as I know he has played with area quite a bit.

One other point... I think that the encoder motor is "delivered" with itself being set in 2W to readily align with the shaft AS part of the replacement exercise / warning is to ensure that the transfer case is in 2W... IF that's not happening then something isn't in place.

 

[AC75TB07]

All I can say is it's not in 4 wheel drive. It doesn't do that hopping thing when you try to do a turn in 4x4. No typical 4x4 sounds either. Tends to grip the road differently than just 2WD, so you can feel it.

In other news, for unrelated reasons, I had my battery disconnected this morning, and when I restarted later in the day, the Service 4x4 light stayed off for about a half hour. I didn't try to engage the system, but IF it was functional for even a short time, would the TC have possibly reverted or returned to the 2WD setting? I understand that the sensor inside the TC motor controls positions and once that sensor fails, it basically shuts the system down, triggering the Service 4x4 light...

Just thinking out loud there...

 

[budwich]

Your "analysis" about the hopping doesn't take into account that IF the front axel activators were not activated, then there would be no connection to the front wheel and thus no hopping even IF the transfer case is sitting in 4W. Have you heard your activators function?

 

[Mooseman]

Really, it won't strip out or nothing? That's why I wouldn't force it...

No. As mentioned, there is a lot of gear reduction and a brake. It's not that hard to turn that shaft. It might be in 4hi but the front axles aren't locked. You can confirm this by trying to turn the front driveshaft.

Alternatively, you can turn the shaft with pliers until it's in the same position as the encoder motor.

 

[AC75TB07]

Your "analysis" about the hopping doesn't take into account that IF the front axel activators were not activated, then there would be no connection to the front wheel and thus no hopping even IF the transfer case is sitting in 4W. Have you heard your activators function?

No, nothing really. What exactly would that sound like?

No. As mentioned, there is a lot of gear reduction and a brake. It's not that hard to turn that shaft. It might be in 4hi but the front axles aren't locked. You can confirm this by trying to turn the front driveshaft.

Alternatively, you can turn the shaft with pliers until it's in the same position as the encoder motor.

Excellent, thanks for the advice.

 

[budwich]

It's in regular RWD right now. The problem originally was the 4x4 service light came on and I wasn't able to shift into any function. A couple times it sorta tried to do something after pulling the ATC fuse, and once unexpectedly it went into 4Hi. Finally everything shut down and the switch only illuminated at startup. I took it to the dealer to get the codes checked and the result was I needed a new TC motor. I got a new one but was having trouble getting it into alignment, worrying that I may wreck something if I put any kind of force on it.

In other news, for unrelated reasons, I had my battery disconnected this morning, and when I restarted later in the day, the Service 4x4 light stayed off for about a half hour. I didn't try to engage the system, but IF it was functional for even a short time, would the TC have possibly reverted or returned to the 2WD setting? I understand that the sensor inside the TC motor controls positions and once that sensor fails, it basically shuts the system down, triggering the Service 4x4 light...

Not sure that you got your money's worth (hopefully it was free).

 

[TJBaker57]

If you can post a picture of the current shaft position I can tell you what range it is in.

for unrelated reasons, I had my battery disconnected this morning, and when I restarted later in the day, the Service 4x4 light stayed off for about a half hour. I didn't try to engage the system, but IF it was functional for even a short time, would the TC have possibly reverted or returned to the 2WD setting

Is your old motor is still installed? If yes then it IS possible that the TCCM could try to set the transfer case range to match the selector switch setting at power-up such as when you reconnected the battery.

I understand that the sensor inside the TC motor controls positions

Technically, the TCCM controls the position of the shift motor. The TCCM uses the signal from the sensor to determine where the motor is and then rotates the motor in the direction needed to match the selector switch.

Worth mentioning that the TCCM rotates the shift motor at different speeds as well so it can make large movements quickly and small adjustments as needed.

What exactly would that sound like?

Here is the sound of a front axle disconnect actuator.

Front Axle Disconnect.mp3

drive.google.com

And this is the sound of a shift motor. You can hear mine struggling a little here.

Encoder Motor.mp3

drive.google.com

And no-one asked but it interesting to know that the range position sensor and the switch signal go live even before you put the key in the ignition. I have a video showing the voltage at the sensor go live by just opening the door. If no further actions are taken like turning the key on etc. that sensor power from the TCCM turns off after 20 seconds.

 

[AC75TB07]

Not sure that you got your money's worth (hopefully it was free).

Huh? What do you mean?

Is your old motor is still installed? If yes then it IS possible that the TCCM could try to set the transfer case range to match the selector switch setting at power-up such as when you reconnected they battery.

Yes, the old one is back on. I haven't had time to dig into it again but when I couldn't get the new one on, I wasn't sure if I should leave it off with the shaft exposed so figured it best to reinstall. Hopefully it moved to its correct position or at least wherever makes installing the new motor easiest.

BTW: will check out your further links tomorrow.

 

[TJBaker57]

wasn't sure if I should leave it off

I would not drive one with the shift motor removed. Far too easy for it to slip into transfer case neutral without the shift motors brake to hold it in position. The transfer case neutral position is right next to the 2Hi position. I would estimate there is only about 20° rotation between them.

 

[budwich]

Huh? What do you mean?

Well, there is no code that says you need a new encoder motor. They should have given you any codes output along with what they did to determine that you need a new encoder motor. As you can see from this thread so far, the system isn't a "simple... it doesn't work, bad encoder, replace it event". There are other things that haven't even been touched on yet like voltages / connections plus physical issues with the transfer case itself... you should be able to turn the shaft as this is one of the "checks" to determine if the case has an issue. Again, depends on what the dealer did to determine what's up.

 

[AC75TB07]

If you can post a picture of the current shaft position I can tell you what range it is in.



Is your old motor is still installed? If yes then it IS possible that the TCCM could try to set the transfer case range to match the selector switch setting at power-up such as when you reconnected the battery.






Technically, the TCCM controls the position of the shift motor. The TCCM uses the signal from the sensor to determine where the motor is and then rotates the motor in the direction needed to match the selector switch.

Worth mentioning that the TCCM rotates the shift motor at different speeds as well so it can make large movements quickly and small adjustments as needed.




Here is the sound of a front axle disconnect actuator.

Front Axle Disconnect.mp3

drive.google.com

And this is the sound of a shift motor. You can hear mine struggling a little here.

Encoder Motor.mp3

drive.google.com

And no-one asked but it interesting to know that the range position sensor and the switch signal go live even before you put the key in the ignition. I have a video showing the voltage at the sensor go live by just opening the door. If no further actions are taken like turning the key on etc. that sensor power from the TCCM turns off after 20 seconds.

Listend to the clips. I'm assuming you recorded those from under the truck cause they are pretty loud... They sound like volumized versions of the sounds the truck makes when the 4x4 works as it should. I do hear the struggle-ish sounds in the recording though.

Well, there is no code that says you need a new encoder motor. They should have given you any codes output along with what they did to determine that you need a new encoder motor. As you can see from this thread so far, the system isn't a "simple... it doesn't work, bad encoder, replace it event". There are other things that haven't even been touched on yet like voltages / connections plus physical issues with the transfer case itself... you should be able to turn the shaft as this is one of the "checks" to determine if the case has an issue. Again, depends on what the dealer did to determine what's up.

Well it took quite a while before the tech guy came back to tell me it was the TC motor so while he says we "ran the scanner for codes", I don't think that was all they did. I know they had the old TC motor off as the guy had it in his hand when he came to tell me it was toast, so I do believe they did due diligence.