I have a 2000 2500 4wd and last march i had a new transmission put in, I have not used the 4wd since the new tranny, until i tried to use it today, when i put the transfer case to 4 high the front axle does not seem to engage and the light on the dash does not come on. If i put the truck in 4 low i get 2wd lo range, which is really cool but would like to have the 4wd back anyone with any suggestions.

 

Like the CAD motor on the front axle.

Check and make sure that the vacuum hoses are connected to it properly and in good condition.

The CAD motor moves a collar which engages the front axle when 4wd is selected, they are famous for failing. I replaced it on my '99 when the same thing happened.

If you do a search you will find lots of info.

 

my vacum hose came loose off the vacum pump and had the same problem...with all the wires and stuff around it i didn't notice it at first....

hope you find the cause....

 

Were is the vaccum hose located is it on the axle or on the transfer case, dodge installed the new transmision and i would bet the kid never hooked it up, they forgot to hookup my HVAC controls also due you think it is possible that the HVAC is also part of the vaccum system.

 

Both.
There are two vacuum hoses that run inbetween the front axle and t-case.

 

yes...if the line is off from the vacum pump you won't be able to change where you vents blow and anything else that's vaccum controled on the truck...

 

Does anyone have a vaccum diagrahm or a picture were the vaccum hose from the vaccum pump to the transfer case?

 

It is a square rubber plug right on top of the TC, four lines to it. Two go down to ports on the crossmember and then to the front axle.

 

You have a black and a red line going to the CAD. One of them is sucking all the time. The one on the left engages the axle and the one on the right disengages it. These run up to the top of the transfer case and are a ***** to get to. Four lines come out from the connector. The green one is a vent that terminates on the passenger side of the firewall. The white one is the source from the left side of the firewall and the master vacuum line. I ran my own vacuum line from the firewall to the axle and ran it through a double solenoid from Grainger to engage my axle whenever I want (as in a 2-LO kit). Here's my fix: https://www.dieseltruckresource.com/...d.php?t=198399
I got the whole thing done for about $60. Now I can have 4WD LO or 2WD LO whenever I want and keep the same CAD setup....

 

Thanks to everyone for their help I finally got the time to fix this problem, and turned out it was the Dealership's fault the vaccum line to the transfer case was discinected. And the fittings were still zipped tied to the fire wall. Just a new fitting minus 1 outlet, I love the Dealerships great care in repairing my truck. It was amazing when I called the manager back and told him This website knows more about there product then they do.

 

Just for gee whiz..
http://www.4x4posi-lok.com/

I'm gonna get this for my truck and Jeep before I get stuck out somewhere with a bad CAD or a vac leak.