Montero Sport -4wd/Hubs won't disengage

[PirateMcGee]

Alright so I posted this on the montero sport forum but there are not very many members over there to respond and everyone defaults to parts I already replaced. So I'll rack your guy's brains since the 4wd system is very similar to the montero (especially since I have the 3.5l).

Background:
Went hunting a few months ago put it in 4wd and it engaged fine. I put it in 2wd and the light just flashed, ABS light came on. So I turned off the truck and restarted it (wasn't aware of the common blinking light issue as I have always had manual hubs) and no lights were on. I figured the hubs disengaged and went about my merry way. Fast forward to a month later and I put the sport in 4wd and no light came on. That kicked off this whole mess.

What's been done so far:
Moved the shift lever in and out of 4wd a billion times and finally the 4wd light started to come back on once the front diff was warmed up enough (it used to come on immediately even when cold). Put it in 2wd and the light just blinks, hubs won't disengage. This is where it has remained.
Replaced the vacuum solenoid (blue and yellow dot) and freewheel detection switch on the actuator/front diff. Nothing changed.
Checked vacuum lines, the blue (keep in default/4wd) line works great and has a solid vacuum. In fact if I swap it's position with the yellow (engage 2wd) it moves the actuator and the hubs disengage. The yellow line seems to never get vacuum and the blue one always does (even if I switch connectors going into vac solenoid).
Pulled the 4wd computer and checked switches on T-case....can't seem to find any sort of issue with the 4lo/4hi detection switch or the 2wd/4wd detection switch however, since the 4wd light only works intermittently it seems nothing works when the light is not on. So which switch actually sends the signal to the vacuum solenoid to switch from yellow to blue?

So I'm lost as to what to do or what to test. It's driving me nuts and I have a big trip coming up in a couple of weeks and won't drive the interstate for hours with the hubs locked the entire time.

Help!

 

[PirateMcGee]

Gah, sometimes I really miss my 86 4runner (simple) and yotatech (have a question? here's 90 billionty answers lol). Looked up the prices of the remaining switches and they cost about $50 a piece. I already spent over $100 on a new vacuum solenoid and freewheel detection switch and after pouring through old records the detection switch had been replaced about 30k miles ago by the previous owner. I think it might be time to switch to manual hubs for about $130-$160 and rid myself of these electronics.

 

[grandpa]

It might be worth while to let the factory tech have a look. It could be something easily fixed once the problem is found. It sounds like you have covered most of problem areas.

 

[PirateMcGee]

Nearest factory tech is an hour + away and will cost me more to diagnose than to put manual hubs on. I might do one more go through, and check the last possible switch (a pita to get to on top of the t-case) but really I think it's a flawed design as sooooooo many people have the blinking 4wd light issue and the switches are not cheap. Best way I see to remedy it is to eliminate the complicated system used to achieve what I can with just two twists of my wrist. Unless of course someone has a simple idea I can check. Really I'm thinking it's probably the 4wd ECU or a wiring issue which is never fun to track down.

 

[Fergie]

http://4epikanini.webs.com/gen3pajero4x4system.htm
http://4wd.blogeasy.com/article.view.run?articleID=318776

Have you tried troubleshooting it from the links above?

 

[PirateMcGee]

yup, thank you though! I guess I really need to apply 12v to both solenoids and see what happens but I think it's 4wd ecu.

 

[shov3lbum]

Hey Pirate! This is monty98 from the 'sport forums. I'll comment here just like I did over there. What you describe about just forgetting about replacing the 4wd parts in favor of just using manual hubs are my thoughts exactly. Just mock up a switch for the actuator detection switch, disconnect the vacuum switches, leave the front axle engaged all the time, and get out to engage/disengage 4wd.

Of course the only concern is keeping the ABS system happy since there are two different modes, but that's where the mock up switch comes in handy.

Maybe someone else can comment on changing a part-time auto-locking hub 4wd system to manual locking hub?

 

[PirateMcGee]

ordered a set of manual hubs from tuffpans.com I'll take pics when I install. I might still try to chase down the gremlin in the stock system but at least now my cv's won't be spinning on the highway (heck maybe I'll pick up an mpg), I'll have 2-lo and a more reliable system.

 

[off-roader]

Good idea on the manual hubs. I have to find mine in the garage and install them. FWIW if you don't fix the problem, your CV's will still spin on the highway. They just won't be connected to your wheels.

 

[PirateMcGee]

So the front drive shaft still spins even if the tcase is in 2wd? Is this thanks to the actuator?

 

[off-roader]

I'm not 100% sure on the sport. On the full size gen 2 montero it has what's called a central axle disconnect (CAD) system that's vacuum actuated.

When you shift into 4wd with your transfer case lever it moves rods in the transfer case that have indents in them. These indents let the solenoids know what position it's in. The solenoids send signals to tell the 4x4 computer what you've selected so it can correctly control the vacuum to connect/disconnect the front drivetrain.

If any one of these components fails, you will have an issue. It could be one of those solenoids not working, or the computer not working or simply a broken wire between the solenoid and the wiring harness it's connected to, or a leaking vacuum line to the CAD, etc...

At least that's the way I understand the system working... but I'm far from an expert in the 4wd system so definitely confirm what I'm suggesting with others.

As for the front driveshaft spinning, not in 2wd. But the front axles & cv joints always spin because they're directly connected to the front wheels. To stop this you can install manual hubs and have them in the unlocked position.

In your case though since you're stuck in 4wd w/ the stock hub setup, they will all be spinning. Installing the hubs won't fix your issue but they will just allow you to disconnect the wheels from the drivetrain so you're not trying to turn them as well.

HTH.

 

[shov3lbum]

When it comes to the 97-99 Montero Sports we have the part time 4wd. So when the transfer case lever is shifted the transfer case is engaged and the passenger side cv half-shaft is engaged to the other half connecting it to the front differential.

Essentially what pirate and I are talking about are installing manual locking hubs that will go in place of the plate that originally permanently locked the cv shaft to the wheel hub. So with the cv shafts being completely disconnected and the front axle being completely disconnected from the transfer case there is no way the front axle would want to turn with the wheels.

The switch we're talking about tricking is simply the switch that tells the ABS and 4wd system whether or not the actuator has engaged the front half-shaft. My ABS works perfectly fine with this switch not functioning properly, for a little while at least, but a quick shift into and out of 4wd (engage/disengage transfer case) puts outs the ABS light and allows my system to function properly for a little while again.

A picture to illustrate :costumed-smiley-007

The back of the steering knuckle where there are needle bearings for the cv shaft to spin freely on.

This plate is the drive flange that the manual locking hub replaces, so basically the cv shaft is completely disconnected from the spinning wheel.

 

[off-roader]

Essentially what pirate and I are talking about are installing manual locking hubs that will go in place of the plate that originally permanently locked the cv shaft to the wheel hub. So with the cv shafts being completely disconnected and the front axle being completely disconnected from the transfer case there is no way the front axle would want to turn with the wheels.

I thought he was having a tech issue disengaging from 4wd. In his first post he states that he puts it in 2wd and it doesn't disengage the front diff/drivetrain from being driven.

Essentially what pirate and I are talking about are installing manual locking hubs that will go in place of the plate that originally permanently locked the cv shaft to the wheel hub. So with the cv shafts being completely disconnected and the front axle being completely disconnected from the transfer case there is no way the front axle would want to turn with the wheels.

Agreed. Thinking about that more, I think you're right. When I did my xcase gear swap, I now recall that once you shift it to 2WD, it is a mechanical disengagement within the xcase in addition to the CAD. Even if the CAD didn't disconnect, the transfer case still won't send power to the front driveshaft.

 

[shov3lbum]

Sorry, off-roader, I came in to this convo with a little more info since pirate (op) also posted on the monterosportonline.com forums. But maybe I'm mistaken also. If, in fact, the transfer case is not disengaging (which isn't likely since then the lever would be stuck as another condition of this due to the direct, metal to metal connection of the lever and xcase).

Is that what is happening also? It sounded (to me) like the front actuator wasn't disengaging the axle, that's all!!

And I am terribly sorry, I wasn't meaning to correct anyone! I looked at your post multiple times, off-roader, and now looking at it again, I DO see what you mean that if the xcase was still engaged then yes, quite obviously the front axle would still spin regardless.. AND further more, I COMPLETELY understand looking at it again what you mean about the switches in the actual xcase telling the computer what to do, and this being a possible problem too...

Thanks for giving me a chance to re-read that!

 

[PirateMcGee]

Haha case is fine. The vacuum solenoids are not getting the signal to engage 2wd using the actuator. I'll let you know how it goes, the manuals will be here next week.