Issue where 4wd light doesn't come on only in 4lo

So I have a 03 double cab with the push button 4wd and manual transfer case select for 4lo. Im having an issue where the 4wd light won't come on when I switch from 2h to 4lo, however it comes on when I push the button for 4h and stays on when I switch from 4h to 4lo. Is this the normal operation for the light/shifting?

Its been a while since I've used 4lo and can't remember if the 4wd light comes on normally when you switch from 2h to 4lo or if you have to switch from 4h first. The 4wd however works in 4h and seems to work in 4l, even without the 4wd light coming on when switching from 2h to 4l.

Some additional info: When the 4wd light was on when switch from 4h to 4lo the diff locker wouldn't engage. I did the grey wire mod to check to see if it was the locker actuator and the locker works fine and now activates in any drive mode. So I've ruled that out as the issue. I have feeling its the 4lo sensor on the transfer case but am not sure.

 

When I go into 4lo I do the following. Press button for 4H, wait for light to come on, put it transmission neutral, put into 4L, back into D. The 4WD light stays on.

 

Thats usually what I do as well but the truck should be able to switch from 2h to 4lo without having to go into 4h first, at least thats my understand after reading the manual. When I go from 2h to 4lo the 4wd light doesn't come on and it won't allow me to engage the rear locker, it also wont engage when I switched from 4h to 4lo and the light stays on for both settings.

If you switch from 2h to 4l does the 4wd light come on?

 

Did you (or a previous owner) do the grey mod to allow 2lo and the locker to be engaged in 2wd? Sounds like it.

 

The manual does state that you can go from 2H to 4L but I've never done it that way. I can try it later when I have access to the truck but I would be surprised if the light doesn't come on anytime 4wd is on since that would sound like an ovetsight by toyota.

 

This happened before the grey wire mod, I did that after the issue arose to rule out the diff locker actuator not working and being the problem.

 

That would be great if you could do that and report back. I assume it'll come on when your in 4lo, which if the case would lead me to believe its the 4lo sensor on my transfer case thats not working and telling the truck its in 4lo when I shift into it with the manual shifter.

 

The light does come on when shifting from 2H to 4L directly.