yes indicator can stay lit even if front axle is not locking in. It's more worried about the position of the encoder motor on the transfer case

 

You will need to physically check the actuator and the vacuum.

 

Ok, that'll be our next step. To check the actuator, just pull the battery after the truck is running and watch it? Or is there a better way to check it?

Thanks
Chris

 

To get 4wd two things need to happen.
1. Transfer case encoder motor puts the transfer case in 4WD.
2. This in turn applies vacuum to the actuator to lock the front axle in.

#1 can happen without #2 and 4wd does not work

 

As long as you have someone to hold the positive cable ...
..or you can pull the line off, replace the battery, and check for vacuum. I'll link to some instructions just a sec.

Looks like the images in the link I as thinking of are broken. We will have to play this by ear. Just remember that the actuator pulls back about 1/2 inch on the cable to engage the mechanism for the front axle, and that the actuator should hold vacuum and not leak. If both vacuum and the actuator test OK (actuator fully applies) and you can still spin the front wheel, then the locking mechanism inside the axle would be at fault (but that is reasonably rare and typically causes a clicking noise). We can deal with any of this, but its up to you to do the actual testing. Could be something as simple as a bad hose.

 

Awesome thanks, we'll take a look at this tomorrow if possible, otherwise it may have to wait till the weekend. Appreciate all the help so far, will update this once we get the chance to look at it.

Chris

 

The good news is that you have it isolated to the vacuum switch, vacuum supply, vacuum switch to cable connection. If the if the vacuum switch s pulling the cable and the cable is pulling the front case then it's internal to the front box but failure of the internals would seem remote to me...

 

I think I know what the problem is. Since my son is 16 and this is his first vehicle, I've been making him do as much of the work as possible so he understands how his truck works and how to fix things when needed. As he was pulling the vacuum actuator out the first time, he said there was a "hose" in there that wasn't connected. It didn't click in my head until yesterday when I was at work. I sent him a text and asked if he hooked up the vacuum line to the actuator or just the cable. He said just the cable because there wasn't a vacuum line that he saw, just the "hose". So pretty sure when we pull the battery and tray out today, hook up that vacuum line, that our problem will be solved. Just one of those things I guess! Will keep you guys updated, appreciate all the input so far!

Chris

 

Got it fixed today. So the hose he saw when we swapped out the vacuum actuator is actually a hose. They routed a hose from the coolant overflow tank down to the fender area. Evidently if/when the overflow gets full, it'll dump it out of that hose and on to the ground. We dug around and found the actual vacuum line for the actuator, it wasn't anywhere close which is why we never saw it the first time and dummy me didn't think twice about it. We routed the hose over to the actuator, hooked it up, put everything back together, jacked up the passenger side and the front wheel would not spin while in 4H. Since we had snow last week I know a few places in the neighborhood that have snow/ice linger around for a week or 2. I got out, he put it in 4H and then 4L and the front tires spun on the ice along with the back ones. 4wd fixed! Thanks to everybody for your comments and suggestions, we appreciate it!

Chris

 

Glad to hear of success!!