Trying find vacuum routing diagram for vacuum line from engine to transfer case to front axle actuator.

Here is a general vacuum hose and line placement diagram for a 2001 Dodge Ram 1500 4x4:

1. The vacuum line from the engine intake manifold should be connected to the vacuum reservoir tank.
2. The vacuum line from the vacuum reservoir tank should be connected to the vacuum actuator on the front axle.
3. The vacuum line from the vacuum actuator on the front axle should be connected to the transfer case.
4. The vacuum line from the transfer case should be connected to the vacuum actuator on the rear axle.
5. The vacuum line from the vacuum actuator on the rear axle should be connected to the vacuum reservoir tank.

It is important to note that the specific placement and routing of vacuum hoses and lines can vary depending on the make and model of your Dodge Ram 1500, as well as any modifications that may have been made to the vehicle. It is always recommended to refer to the manufacturer's instructions or a repair manual specific to your vehicle for accurate information. Additionally, it may be helpful to take pictures or label the hoses and lines before removing them to ensure proper reinstallation.

does not work,means?
1: lamps in dash told me that
2: front axle dead, on ice?
3: FRONT Prop shaft dead, on ice or stands?
4: front prop ok,(spins but front axles is dead.
we cant guess what not works means.
this part time4wd, and only works on ice or dirt
its not TOD, nor AWD, like on say a Trooper.
its the old PT 4wd, and has strict rules for usage

ill pretend it fails on ice, below....

automatic or stick shift box? main?
this part time system is for iced roads or offroad
have you tested it off road yet? (or on iced over pavement?) Unlike TOD system (torque on demand)
also you can test it all out on jack stands.
lots of steps to that, do need all that. ?
any 4wd shop in town knows all the steps.
called hand testing 4wd. (part time 4wd)
what we do is make sure the the transfer case works
by hand,
then front axle left to right to center works.
I an also do this just front end off the ground,
is car automatic or stick shift. tests vary that
starting in 1996,the new front axle uses SHIFT on the FLy,part time 4wd, and can be tested on stands. Jack stands. got those>?


the front axle has vsv vacuum actuator(or elect motor)
that locks the front axle.
there are many systems of 4wd, and even Part time.
this one Vacuum, operated, and to test it
other than having vacuum pump like me (portable)
means you must have engine running to test it on stands. hint, lots more dangerous.
first i jackup whole car on stands x4
and put car in say 1st gear, or a/t in low.
then TRANSFER CASE TO 4WD.
AND MAKE SURE THE front prop shaft spins. at a distance , if yes the trans fer case works.
all 4 wheels spin, (no people or pets near car0
and someone in drives seat ,not you, for safety.
hand brake is off. (sure0
my guess now is the front wheels are dead.
back wheels must spin , if brakes drag, one will slower.. (oops another problem)
but front is dead, and so is the front actuator dead. the front prop shafts spins, but of the actuator is dead, the left axle unlocks.
to discover why, takes a vacuum pump
as no sane person would go under running engine with 2 live prop shafts. are you following me?

what i do is test the actuator with only left
wheel side on jack stands, right tire ground
the actuator is right there, see its vacuum diaphram casing, sure, see its vacuum nipple
i apply vacuum there.


engine off,
in 4wd, park (a/t) or m/t in 1st gear.
i apply say 10 inches of vacuum or more.
causes the actuator to move and the tire left locks up. (feel by hand turning tire)
the front prop shaft can not move. in this mode.
allowing me to test left front lock.
if spins free, the actuator is failing
if this locks, then the cars vacuum switches are failing. more tests.
im not going to document this part, (too long)

this is very simular to a jeep system with vacuum
other cars use a pressure pump there.
all versions of 4wd have different ways to test
in a shop.

why not go a 4wd shop. and get help
or any ASE shop in town?

that was the easy part.

the motor version, we hot wire the motor
to see it work.
using this drawing



unplug it first
hot wire the 2 pins,
always observe polarity
check voltage there in 4wd
if 12vdc there, then the controls are are working
and if yes,,you now know which pin is Plus.
my guess pin 4 is plus 12v
this step replaces vsv tests above.
its just an electric motor here.

the transfer case (frontprop shaft dead symptoms)
on this car it has motor too.
there.
and a controller

the controller need the backup fuse good
then the transmission not in neutral,sends
12vdc power from neutral (not) goes to the controller to the motor drive controller
testing all this is tedious.
id check the motor there first on the transfer case.
mitchells has the drawings for all this.
see them now.

What model

THERE IS AN ACUATOR ON THE FRONT DIFFERENTIAL VERY EASY TO CHANGE CHECK THIS PART

The vacuum actuator should move by hand without vacuum applied. You should also be able to see it move if you have someone switch the transfer case into 4hi/lo from 2wd and then back again. There is a vacuum switch on top of the transfer case that locks vacuum once the encoder motor engages the transfer case to lock the front axle into position, and then releases the vacuum once the encoder switches back into 2wd mode allowing the front axle to decouple. If you aren't getting vacuum, first check your vacuum lines for leaks, then check for vacuum coming from the transfer case when it's in 2wd mode.

The 4x4 system on an 88-98 full size gmtruck is controlled electronically except the shifting of thetransfer case which is done with a lever. When the transfer case isshifted into a 4x4 gear a switch in the upper driver side of thetransfer case is closed this sends power to the front axle actuatorwhich engages the front wheels to the front axle. A sensor is alsolocated on the front axle which is closed when the actuator shiftsthe axle into gear.

The first thing to check is the 4x4fuse if it is bad replace it.
Next check the switch on the transfercase connect a continuity tester to the switch and shift the transfercase into 4x4 the stitch should close, if it dose not replace it ifthe switch is functioning properly replace actuator on front axle

there is an actuator under the hood that is vacuum run and engages the front axle check both the vacuum actuator under the hood and the engagment piece on front axle.

if you crawl under the vehicle, trace vacuum lines to transfer case they terinate in a group of 3 (vent, vacuum from engine, line to actuator diaphram under battery) . Mark lines (bundle should have a pin to prevent bad replacement, but be safe) pop 3 hose unit , unscrew switch (count the turns to return it to same position). Transfer case side has a ball that should detent fairly easily. If stuck, work it loose or replace the switch. This manual detented switchsimply routes vacuum to diaphram which pulls cable to front axle, or vents it to atmosphere when in 2wd.

You should be able to feel if diaphram is pulling in when in 4wd and is relaxed when in 2wd mode to troubleshoot. Direct vaccum to diaphram line to test. I have used aquarium airline tubing and airstone manifold to provide quick fix when a garage and/or access to parts was not available. You want to be able to direct vent to diaphram for 2wd and engine vacuum to diaphram for 4wd.

there is a vacuum solonoid on the firewall in the middle with 2 vac lines and a 2 wire plug
thats ur problem
push the button and smack it with the handle of a screwdriver should work

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