Clicking sound in 4wd

Hi,

I have a 99, and there is a clicking sound in 4wd. Here are the symptoms:

- clicking when in 4 hi or low on accelerator (no clicking in 2wd)
- no tire spin from either of the front wheels
- driver CV does not spin when on the gas (couldn’t tell about passenger)
- 4wd indicator lights up and rear diff lock works in 4lo

CV boots are torn, but I would think they’d click in 2wd

Any ideas? Vacuum system -ADD?

 

See the attached troubleshooting docs in my post here. Might be helpful.

https://www.tacomaworld.com/threads/4wd-not-engaging-and-light-not-working.783856/#post-28038699