Post-regear Tcase diff lock issues ‘91 (1 Viewer)

[Froski]

So I regeared the T-case on my ‘91 and everything works except the center diff lock.
I have been trying to figure out what went wrong. I have tested and / or replaced the switches ( indicator switch on the front, neutral position switch rear left and 4lo switch rear right. All seem to be working. Also, the first FSM test for resistance on the actuator seems fine. The second (pin 2 or 3 to ground) does not return any value.
I put a 9 volt battery between pins 2 and 3 and got motor sounds as well as when I reversed positive and negative.
I jumped the 4wd indicator harness with a paper clip and got the diff light to go on.
Anybody have any experience with this?
Is there something simple I forgot when putting it all back together?
I put it in 4lo before I dropped the case.
Any help is appreciated

 

[Froski]

So I regeared the T-case on my ‘91 and everything works except the center diff lock.
I have been trying to figure out what went wrong. I have tested and / or replaced the switches ( indicator switch on the front, neutral position switch rear left and 4lo switch rear right. All seem to be working. Also, the first FSM test for resistance on the actuator seems fine. The second (pin 2 or 3 to ground) does not return any value.
I put a 9 volt battery between pins 2 and 3 and got motor sounds as well as when I reversed positive and negative.
I jumped the 4wd indicator harness with a paper clip and got the diff light to go on.
Anybody have any experience with this?
Is there something simple I forgot when putting it all back together?
I put it in 4lo before I dropped the case.
Any help is appreciated

Difflock was working before I dropped the case

 

[jonheld]

If the ONLY thing that's not working is the CDL, then the problem is with the actuator. It's possible to have it locked when disassembling, and put it back in the unlocked position. Now the actuator is out of phase with the CD itself.
I would verify that the CD is either locked or unlocked simply by rotating the output shafts on either end. Run the actuator motor with a 9V battery to one direction and reinstall. Test operation. If failed, then remove actuator, run motor in opposite direction and reinstall.

 

[Froski]

Ok, so I tried both positions of the actuator as it is, connected to the case. Are you saying the next step is to pop it off the case and run it to the opposite end of it’s travel?

 

[Froski]

Wait I am getting it now. I have to pop it off the case and run it to the other end of it’s travel

 

[Froski]

Alright, a fresh 9v is not moving the actuator now that I have it off the case. Can the actuator be refurbished or is the ticket a new one?

 

[jonheld]

Alright, a fresh 9v is not moving the actuator now that I have it off the case. Can the actuator be refurbished or is the ticket a new one?

If the actuator motor was working before you removed it, I see no reason why it wouldn't work off the truck. Are you certain you're on the correct pins? The motor is pins 2 and 3.

 

[Froski]

Yes, those are the pins I have been using, switching the positive and negative back and forth. Here is a theory: motor was close to failure already, then installed out of phase. Received current and tried to move against the limit of the mechanism and fried itself.
Plausible?

 

[Froski]

Perhaps I should try with 12v from the battery

 

[Froski]

Thinking about it, I did not confirm the diff was locked when I put the case back on. So it is possible the motor was locked and the shift yoke was unlocked. I hope I didn’t fry my actuator. Does it get 12v from the relay?

 

[mudgudgeon]

Yes, those are the pins I have been using, switching the positive and negative back and forth. Here is a theory: motor was close to failure already, then installed out of phase. Received current and tried to move against the limit of the mechanism and fried itself.
Plausible?

Yes.
I had one fail. One of the motor windings burnt out. Pretty sure I fried it.

The motor worked when tested with a battery on the bench, but wouldn't work when bolted in and under load.

Mine smelt burnt though

 

[Pz10420]

I had mine out of phase when I regeared about a year ago. I just pulled the actuator off of the case and used the dash switch to actuate it to the other position and then reinstalled into the transfer case.

 

[Froski]

Thanks! You got me back in business!
Just a little sorting out required.

 

[Marco Lau]

Thanks! You got me back in business!
Just a little sorting out required.

View attachment 2806520

u have 65k miles on your odometer?

 

[Froski]

There’s a one hiding in the shade on the left there. But none of it was spinning when I got it so who knows...