When I try to engage the four wheel drive on my dodge 2500 the transfer case will lock in but the vacuum actuator dosn't engage. Took vacuum lines off at the transmisson and there is no air getting pushed through the lines. Need to know my next step, or other checks to perfrom.
Axle lock on dodge is very simple and for the most part trouble free i thought i had the same prblem turned out it had shatterd the center pin in the front diff jack up right front tire set park brake lock in 4 wheel drive engine must be running for vacum to engage axle disconnect so in park or neutral only now by hand spin right front tire it will either only rock back and forth just about a 10th of a turn or will spin the front driveline ....... should only spin if in neutral ....... if it spins in park and driveline doesnt spin and left front in on the ground front diff is the problem
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the front axles have pinon gear box that the shaft from the transfer case goes to, it has a vacuum hose to it or a solenoid actuator check these for proper function this is how the power is turned on to the wheels.
actually that first soultion is wrong it is correct on smaller pickups but on the full size pick ups they use a differnet sytem
there a electric actuator on front axle
there be two elctrical plugs on front axle u want the bigger of the two other one is just to turn the 4 wheel drive light on
un plug actuator then remove actuator after it removed plug it back in but leave it out of axle turn key on and shift down to 4 wheel drive the actuator should move out if it dont that your problem if i does move this isnt your problem it either the tranfer case or in front axle
shift into 4wd and move truck a couple of feet.
if light is still off, park truck block the wheels set the park brake jack right front wheel and try to hand spin the wheel if wheel doesn't turn 4x4 is functioning properly but there is a wiring problem use an ohmmeter to check the 4x4 switch wiring fuse and bulb
if wheel turns freely the front axle or transfer case is not engaged
attempt to hand spin the front driveshft if the driveshaft will spin the transfer case is not engaged check the transfer case shift linkage, problem is in linkage or transfer case internals
if the driveshaft will not spin the transfer case is engaged properly
with trnsmission in neutral or park start engine measure vacuum on the two vac lines at front axle shift motor . one line should have approx 20" vacuum. other line should have none
if no vacuum measured look for vac leak or bad vac switch
if both lines have vac look for a bad vac swithc or ruptured cad actuator diaphragm
if one line has 20" +- VAC
move transfer case lever to 2wd measure vac again lines should have swapped vac signals
if no vac switch bad or 4wd shift likage needs adjusting
if yes vac motor bad or stuck or shift fork stuck
remove vac shift motor from the axle attach vac lines to shift motor engage disengage 4wd
does shift motor plunger move at least 1/2 inch
no shift motor bad
yes check axle shift fork and vac motor for binging
On the axle there is a vacuum Actuator that engages a collar on the axle that engages the four wheel drive if the axel splines are worn or havent been lined up they will get burred and won't allow the collar to line up. You can remove the actuator and see the splines and determine if they need to be fixed.