(1998 Ranger, 3.0, 5 speed manual, 4x4) Vacuum Tubes Disconnected from 4x4 Solenoid

ernest_pizza · May 13, 2018

(1998 Ranger, 3.0, 5 speed manual, 4x4)

Hello everyone,

The 4x4 on my 1998 Ranger is not currently working, and while trying to fix it I found that there are two vacuum tubes that lead from the 4x4 solenoid but do not connect to anything.

After looking at a diagram it seems to me that the vacuum line that's supposed to lead from the vacuum reservoir (black cylinder-shaped object above the passenger side fender?) into the 4x4 solenoid has been rerouted such that instead of connecting to the solenoid it connects directly to the two vacuum tubes that lead to either wheel. I'm assuming it's the solenoid's lack of connectivity with the rest of the system that's the root of my problem. I've attached some diagrams below to help illustrate the situation (the ones with the colored circles are showing my current situation, and the one with no colored circles shows what I think is the correct configuration. The colored circles in the diagram indicate the same components as the ones that are circled in the photograph.).

Some more details about my situation: When I'm in 4x2 I can freely rotate the front CV axles that are attached to the front diff, and when I'm in 4x4 I can't rotate them. I believe this is a sign that the hubs are locking properly but the front diff isn't engaging? Could it be possible that the vacuum lines that go to the wheels are what controls the hubs locking but the solenoid (which is currently disconnected from the system) controls the front diff engagement?

Anyways, how would you guys recommend I remedy this situation? Thanks for any answers!

RonD · May 13, 2018

Vacuum holds the PVH hubs LOCKED, no vacuum is UNLOCKED

The vacuum reservoir is used because it holds a steady vacuum regardless of changing vacuum in the intake manifold.

Vacuum is not "used up", all hoses and vacuum devices are sealed, but there will be small leaks, lol.

In the current hose routing your hubs should be LOCKED full time.
They should always have vacuum when engine is running.
You should check the hose to each hub with vaccum pump and gauge, or use the poorman's method, pull hose off at the "T" and suck on it, it should hold that vacuum, if you can suck air thru that hose then hub is bad, not sealed, or hose is.

My guess would be that the PVH solenoid was not working, and previous owner needed 4WD so applied vacuum to hubs full time.

PVH solenoid is just a 12volt valve that applied vacuum to the hubs when 4WD was selected by switch on dash and then GEM module(4x4 controller).

You can test the PVH solenoid with a 9volt battery, it has no polarity, touch its 2 connections with 9v(+) and ground(-) and you should hear it click
You can use car battery as well with jumper wires.
If no click then solenoid is dead/bad

If it clicks then blow into either hose on solenoid, you should not be able to blow thru either hose, then add power to solenoid and you should be able to blow thru it.

If it test OK then hook one of its hose to vacuum reservoir "T" and the other to Hub "T", doesn't matter which goes to which, its just a valve either open or closed

fastpakr · May 13, 2018

Ron, unless I'm misunderstanding you, that's not how the system works. Vacuum isn't applied to the hubs full time. The mechanism cycles between two positions when vacuum is applied and removed, kind of like a ball point pen. Vacuum is applied for a certain amount of time to pull the assembly inwards, then it's released and the hub changes mode.

RonD · May 13, 2018

Yes, it is "Pulsed Vacuum" to lock hubs, but full time will also keep them locked

When vacuum at hubs is above 8" they will engage(instantly), under 8" disengage(after about 15 seconds or so, so not instant)
The Pulse part is so it won't drain vacuum reservoir while in 4WD if there is an open hose or Hub leak, as that would disable HVAC vent control, as well as hubs

Vacuum reservoir should maintain above 14" vacuum unless there is a leak, so high enough to run HVAC vents and PVH

I have only worked on two Rangers with PVH problems, so maybe I took away the wrong impression of its operation, but it seems pretty straight forward.
Fixed leaks in hoses and got them to work, recommended Rugged Ridge hubs as permanent fix,

ernest_pizza · May 13, 2018

Thank you guys, shouldn't the fact that my front CV axles can be turned when in 4x2 (manually, by hand, when the car is stopped), but can't be turned when in 4x4 suggest that the hubs are not locked full time though?

Also, the 4x4 light does come on on the dash when I shift into 4x4, if that's of any importance.

RonD · May 13, 2018

Yes that would indicated hubs are not working, but not a big surprise for PVH hubs.

The 4x4 lights indicate Transfer Case position, there are contacts in the transfer case shift motor that open and close as shift motor turns the shift rod in the transfer case.
When contacts are in the correct position for selected position the 4x4 light for that position will come on.
That's why there should be a slight delay between selecting a position and the light coming on, the shift motor must turn shift rod before light will come on.

There is no indicator for front hub positions
PVH hubs should be thrown out and replaced with AVM/Rugged Ridge manual hubs

ernest_pizza · May 16, 2018

Alright I've been convinced, I'll try to get some manual hubs asap and stop trying to deal with these vacuum ones.

don4331 · May 16, 2018

If you can spin the shafts in 4x2; they are released.

If you can't spin the shafts in 4x4; then at least one hub is engaged.

So, jack up left front wheel in 4x4, see if you can spin. If not, move to right front and repeat - either at step a or b, you have found your trouble maker.

Then you can check the lines for leak before you spend coin on manual hubs. (I upgraded to full time unit bearings/axles when I installed the Explorer V-8, but that was more about being able to use the Explorer transfer case...)

(1998 Ranger, 3.0, 5 speed manual, 4x4) Vacuum Tubes Disconnected from 4x4 Solenoid

ernest_pizza

New Member

Attachments

RonD

Official TRS AI

fastpakr

Forum Staff Member

RonD

Official TRS AI

ernest_pizza

New Member

RonD

Official TRS AI

ernest_pizza

New Member

don4331

Well-Known Member

Sponsored Ad

Sponsored Ad

Members online

Member & Vendor Upgrades

Latest posts

Truck of The Month

Recently Featured

Follow TRS On Instagram

Latest Album Photos

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store

Sponsored Ad

Sponsored Ad

Sponsored Ad

Amazon Deals