Transfer case noob question

[drdoug]

I have a 1995 control trac XLT. I’m getting mixed info about what my transfer case motor does.

from what I read it assists in changing from 2wd to 4x4 auto or 4x4 low.

what I’m trying to determine is if it’s going bad does it just stop working ? Might it allow initial engagement of 4x4 then quit ? Sometimes the lights blink sometimes 4x4 light goes out.
Which speed sensor is the 4x4 auto dependent on ?
thanks again.

 

[drdoom]

Shift encoder motor shifts in and out of LOW range (and neutral, if you have that option).
4x4 AUTO uses not the VSS, but two other sensors on the transfer case, front output shaft speed, and rear output shaft speed. When a disparity is detected between the two (rear wheel slip) then power is added to the front.

 

[drdoom]

Doug, if you can read live data on your scan tool, I suggest looking at the shaft speeds...in good traction conditions they should match. Please understand I am not familiar with OBD1, only OBD2.

 

[drdoug]

Doug, if you can read live data on your scan tool, I suggest looking at the shaft speeds...in good traction conditions they should match. Please understand I am not familiar with OBD1, only OBD2.

Thanks again DrDoom !