Post-regear Tcase diff lock issues ‘91

Joined
Dec 9, 2019
Messages
90
Location
Frisco Co
Website
www.bighollowguitars.com
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
 
Joined
Dec 9, 2019
Messages
90
Location
Frisco Co
Website
www.bighollowguitars.com
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
 
Joined
Dec 8, 2006
Messages
10,277
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New Jersey
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www.sdsysdesign.com
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.
 
Joined
Dec 9, 2019
Messages
90
Location
Frisco Co
Website
www.bighollowguitars.com
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?
 
Joined
Dec 8, 2006
Messages
10,277
Location
New Jersey
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www.sdsysdesign.com
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.

CDL Connector.JPG
 
Joined
Dec 9, 2019
Messages
90
Location
Frisco Co
Website
www.bighollowguitars.com
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?
 
Joined
Dec 9, 2019
Messages
90
Location
Frisco Co
Website
www.bighollowguitars.com
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?
 
Joined
Dec 17, 2007
Messages
5,240
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Across the pond, and upside down
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
 
Joined
Jan 3, 2020
Messages
57
Location
Monument COLORADO
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.
 

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