hi i have a 98 ram 1500 4x4. my 4wd hasnt been working for a while now and after looking over the threads here i started trying to hunt down the problem and am at a stand still. the transfer case locks in and i tested the CAD vacuum lines and what i found was that when in 2wd the one vac line is about 20 while the other is zero then once i engage the transfer case they both drop to zero which from what i gather is why the the axle is not engaging. iv replaced the vac switch on top of the transfer case and looked over all the vac lines and cant seem to find out whats wrong. please help

 

You sure you got the lines connected back on the switch the correct way?

 

When mine did that I had the same trouble finding the issue. It turns out there was a hole in one of the metal vacuum lines that runs along the frame rail. Mine actually stayed locked rather than not going in, but same cause. Just go over those lines with a fine toothed comb-- 99.9% it's a vacuum leak.

 

Yea, use the gauge to check each line isolated by themselves. Use the gauge as a pump if you have that type.

 

its on the frame rail, it goes around the cat, and the heat kills it... its in the lines, mine did it too... until i replaced them with all copper lines.... and where it goes past the cat or anywhere near the exhaust, i wrapped the copper in som fuel line that is snug on the line.. never had any problems with it...


or you can do what i now have and put on a posilock cable, eliminates all vac... and puts in a beefy cable....

http://www.4x4posi-lok.com/app_dodge.html

 

maybe a bad accuator

 

Its the vaccum lines under your truck. Mine did the same thing, and as soon as i pluged it back in it started working again and has been fine since.

 

Just get the Posi-Lok system its better than stupid vac lines anyday plus it takes the guess work out

http://www.4x4posi-lok.com/app_dodge.html

 

Thanks alot guys it ended up being the hard black vac line on the top of the tranny. must have rotted out but thanks for all the help. -chris-