Does anyone know if the vacuum pump that is located on the passenger side of the truck (under the hood) controls the front differential..? I replaced the heads and after i got the truck put back together the front will not lock in you can feel the transfer case engage but no front axel will not engage can some one HELP I want my 4X4 back....I had to fix one of the vacuum lines that goes to what they call the vacuum pump that is located on the front axel. The truck is a 1999 Dodge ram 1500 4X4 with the 5.9

 

You may have accidentally disconnected one of the vacuum lines running to your CAD (Central Axle Disconnect) unit while you were replacing the headers. They run from a vacuum switch at the top of the T-case to the CAD on the passengar side of the axle.

 

Well i check all the the vacuum lines they all seem to be connected...Is there any fuses for the transfer case or the vacuum pump? the books you buy at the part stores don't talk much about the Transfer case or the front Axel.

 

the best thing to do is get a vacumme gauge and check for vac at the diff switch fork. you should have vac on 1 side in 2wd and on the other side in 4wd. check the 2 smallsteel lines on the pass side frame. these get over looked a lot. if vac is ok you have a seized actuator on the diff. if vac dont change lines from 2-4wd. you need a vac switch on the t-case

 

Thanks that is some good info I am going to check that when I get home tonight..If the vac. switch is bad could that cause no vac. in both sides?

 

yes and that pump thing under your hood. if that is the one under the battery that is for the cruise control.

 

The pump is on the other side is behind the passanger head light