Thanks for the info, Jon! I never owned a FJ80, but I remember you had a '91. I guess the OP has a '93 that kinda fell in between the FJ80 and the FZJ80 with all the "upgrades". Some were an improvement, and some were at best, questionable. The VC and no CDL switch for example.The FJ80 had the CDL switch to enable the driver to lock the center in high range. Remember, it came with 3 open diffs. The FZJ80 had a viscous coupler in the center diff, so apparently the engineers felt that it was sufficient for 99% of situations. After daily driving both for many years I tend to agree.
On the FJ80 all that's needed is to remove the low range sensor plug off of the transfer case. This gives you manual control of the CDL in L and H.
Alternatively, you can ground pin 7 of the CDL relay and this will give you manual control as well. However removing the plug on the transfer case is completely non-invasive.
The difference between a pin 7 mod on an FZJ vs. an FJ is the transmission shift points. The FZJ has an electronically controlled transmission. In low range the shift points change. The A440F in the FJ80 is hydraulic, so it doesn't care what you do.