my truck wont go into 4x4 when I shift the transfer case and light wont come on either. I know that there are four lines that go to the t case red, black, green and white.

I have checked the vacuum in the lines when in 4 hi the black line has vacuum but the rest do not. this is before the metal tubing that routes on the passenger side to the actuator.

when I checked the lines at the actuator I found that I did not have vacuum. could this mean that the metal tubing in between the red and black lines are bad? or is it my switch on the t case?

also I found out that the green line is not connected to anything and its just hanging by the bell housing. should this be connected to anything if so where does this line connect to?

need answers asap I would like to get four wheel drive for winter again. please and thank you.

 

Anything is possible.

It sounds like you have decent understanding of the vac lines. Here's this link just for the hell of it.

http://dodgeram.org/tech/repair/4X4/4x4_engagment.htm

When the lines come down from the engine they go to the passenger frame rail. At the frame rail is the only length that is hardline, 2 of them. It runs all the way to the tranny crossmember and over in front of the tcase. Then a set of soft lines from there go to the top of the tcase, which looks like this (photo courtesy of merc225hp).



This is the switch in the tcase:



Next place to check for vac is right at this hardline to soft line on the cross member. If no vacuum is found there, then next place is connections to the switch, which will probably be a real pain due to access. 2 lines from the bottom go to the top switch. The other 2 on the top, b/c it's 4 port, are for a vent and another going back to the engine for vacuum source.

Merc or someone else knows the colors better than I do, but those might be the next things to check to rule out where the vac loss is possibly occurring. You are on the right track and just need to expand it.

Also, it might easier to diagnose by putting front axle up on jack stands. Leave in Park. Shifting the tcase "should" have very close to immediate action. Disengaged then spinning a tire one direction will be very easy and/or make the opposite spin opposite direction. Engaged then little harder to spin and they spin same direction.

 

So that switch is just threaded into the transfer case? Is its only function to switch vacuum between the two lines going to the CAD?

 

Sorry but I do not know the colours of those vac lines, mine are all faded to gray lol. HeyYou and Zman are very familiar with them though. I think the green one is a vent line that runs up the firewall.

@AppelH, You got it.

I will be doing xcase work today and I will see whats what for those lines (as for their colour and so on)

 

Wish I had known that before we bypassed it. We thought there was something inside the t case that really wasn't easily serviceable

 

thanks guys for all the help. I did notice that the vent line is not connected to anything also looks like there some kind of check vavke on there. im just not shure what that hooks up to.

I did check for vacuum where the soft lines connect to hard in fron of the transfer case. I do have vacuum there. but it seems like I cant get vacuum passed the hard lines. would the hardline be the problem?

 

Yes. Either rusted out, or just plugged up. Take 'em off, and inspect. See what ya got.

The green line is just a vent line, the cap on the end is a filter, (so it doesn't suck dirt). It doesn't connect to anything on that end. Just make sure it is up out of the way, and won't suck water, or, be burnt by something nice and warm. (exhaust manifold comes to mind.)

 

Yeah +1 to what HeyYou said. The check valve typically is residing behind the distributor so that it stays up high.

Here is picture of my lines, which I'm sure you may have seen already. Green as said is vent as evidenced by where the plug to on tranny and tcase.

White is VAC source.

Black/Red is for the CAD.



The infamous switch



I needed to look at this in order to determine my bypass method, which will be ~$50 and allow independent engagement of the front. This just takes the tcase switch out of the mix and adds another nifty lever.