99 Jimmy Whats this code mean?

I have a 99 Jimmy 4WD. I have not been able to shift into 4wd in over a year. I can generate a code only when attempting to shift to 4 LO. I will get a code (forgot number) definition is (unable to complete shift). otherwise if I try to shift into 4HI it would just blink and revert back to 2HI with no errors.

Now just today the light came on by itself and it generated a C0323 code (transfer case lock circuit low). Before I spend a fortune on this does anyone have any ideas. I bought a shift motor on ebay I was going to try that before I got the new code.

Also, I know you have to pull the front drive shaft to change the shift motor but do you have to pull anything else (crossmember ect) to get it out?

99 Jimmy SLT 4.3 liter auto transmission autotrack transfer case (with auto 4wd button)

Where are the experts at? no transmission guys on this fourm?

Read the FAQ section post on 4wd problems. Also check the wiring up under the xfer on drivers side for cuts/bare spots/nicks - seen that as the bundle drops.