4wd won't engage

Recently I purchased 2007 TRD Sport extended cab and just the other day the 4wd stopped engaging (no light/no click/nothing). I'm not even sure how to begin to troubleshoot, even having looked at a few posts here.

Can someone direct me to what would be a good approach to troubleshoot the 4wd?

 

I’d approach it by checking the 20A 4WD fuse.
If that’s not it, it’s probably going to get “complicated”
But next would be the actual switch since you say “nothing happens”.

Good luck to you.

 

Thanks, and I should have mentioned that checking the fuse was the first thing, and of course, to no avail. Still seeking guidance...

 

Maybe something to do with the actuator?
https://www.tacomaworld.com/threads/how-to-trouble-shoot-4x4-actuator.263525/

 

OP, check your PM in box. I sent you some diagnostics that should help.

 

Hi Taco'09, could you send me the diagnostics also? Mine does the same as the OP occasionally and it's been doing it more often recently. No light, no click or actual engagement.

Never Mind Taco'09, OP sent them.

 

To follow up a bit. I tapped the actuator a few times with a wrench, and was eventually able to start the truck in 4wd. For the next week it worked without issue, even when started with 2wd. Last night, after leaving a ranch road, it suddenly did not engage. No light, no click, nothing... time to go back to the drawing board