Thanks for all of the information that's been shared so far in this thread. Amazing support.

I'm dealing with a very similar issue that's been discussed.
I have a new to me 1999 4Runner, SR5, 3.4L 5-speed with a j-shift transfer case.
The original symptoms were: no dash 4wd light when moving j-shifter to 4HI, N, and 4LO. When driving in 4LO, it was obvious that it had shifted to LObecause it was slow to move, high revs, etc.

I replaced the bulb for the dash 4wd light with a known working bulb (I had the dash out anyway for something else)

Checking vacuum:

• When in 2HI and shifting to 4HI, vacuum remained on the same nipple.

• Shifting from 4HI to 4LO, vacuum switched to the other nipple.

• Shifted back from 4LO to 4HI, and switched the vacuum lines to force it into 4HI.

• This worked and allowed for 4HI driving.

• Reset vacuum lines as they were originally. At no point did the dash 4wd indicator light up during this testing.

At this point I know that the vacuum lines and VSV are good. I also know that the front diff is functional.

Transfer Case Wiring Testing:
I then got under the truck to examine the transfer case position switch wiring since I know that the clutch has been replaced at one point.

• Both switch pigtails have gray wires

• The driver side switch(4LO) switch was connected to the blue wire with red stripe. The passenger side switch(4HI) was connected to the solid blue wire.

• Although the harness look like they were installed correctly and didnt have much slack, I unplugged the switches from the connectors and switched them.

• Now the driver side switch (4LO) is connected to the solid blue wire and the passenger side switch(4HI) is connected to the blue wire with red stripe.

• When shifting from 2HI to 4HI, the dash 4wd light does not illuminate and the vacuum does not switch sides.

• Shifting from 4HI to 4LO, the dash 4wd light illuminates and the vacuum switched sides.

At this point, the symptoms are identical to what 99Runner had with just switched wiring.
I am guessing that my passenger side 4HI switch is bad, but have not specifically checked it with a multimeter; that's the next step.

TheDurk or anyone else, do you have any ideas as to what might be causing the original issue?

Also, can someone walk through the process and tools they used to remove the transfer case 4HI and 4LO switches? Did you remove them from above or below - is one way easier than the other?

Thanks in advance for any troubleshooting advice that can be offered.