Four wheel drive will not engage

First inspect the vacuum lines going to the front hubs to be sure they are OK. If so Verify vacuum to them with a gauge. If both are OK you may have bad seals in the hubs

Okay, to start vacuum hubs work by first when you put it in four wheel drive the engine vacuum pressures up a canister with vacuum and the vacuum stays sealed in the canister throughout the lines to the hubs, when engaged the vacuum pressure engages the hubs, but if a hose is broken the vacuum leaks out until it has no pressure and hubs unlock, i have an 1998 four wheel drive and i know this by experience. so anyone can call me on it but i found when i got mine that the right tire hub, the vacuum hose to it right where it connects to the tire was cracked and it bleed the vacuum and hubs just disengaged so to start i would remove front tires and look on inside of assembly at vacuum lines for crack or anything then if no problem trace lines to engine looking for any problem if no problem remove vacuum line from engine and see if it is even getting vacuum. try this and get back to me.

vacuum reservoir tank and bracket is located either on or beneath the RH front fender splash shield.

See the vacuum diagram below

I have a 1999 Ford Ranger four wheel drive manual. How I found out front wheel drive was not working was the AC would not blow into the cabin at high speed or hard acceleration. I found a broken vacuum line on the right side, so I replaced it and AC works and so does the right tire engage. My left is an issue, The left locking hub is always engaged so I will work on that this coming week. I did find replacement manual hubs at www.therangerstation.com (AVM Locking Hub)for $160.00, but I have not tried or bought them yet if I can not get the vacuum ones to work property. While I am on that side I am replacing the 1/2 axle it leaks and has a broken boot.

All these comments are great to read. Educational, would not of known about vacuum, I figure it was all electrical

Use 2CarPros anytime, we are here to help. Please tell a friend.

I can turn the switch on the dash to 4 high or 4 low. I tacts like it kicks in but the front wheels will not pull. I jacked up the rear wheels and tried to drive off in 4 low and 4 high. the back wheels spun but would not pull. I remov ed the electric motor and it is working fine.It has a whining sound in the front end like the 4 wheel is working bu the front wheels will not pull or spin on the rear wheels.

I have the exact same problem on my 1999 Ford Ranger 4x4. I believe the vaccum lines on mine are bad but i haven't got them fixed b/c I did what this page said.
It is really helpfull to have manual hubs and it only taked 10 minutes to add them. I'll probably get the vaccum lines replaced soon so i'll have both manual and shift-on-the-fly! Good luck!

I had to replace the wheel bearings this summer (came with the whole hub assembly). Before I did that, my four wheel drive worked fine. I bought my wheel bearings from Ford, so they should be a perfect fit. Now, with winter snow, I turn the 4x4 on and my front wheels don't move. I've lifted the truck up and engaged four wheel, the front drive shaft and axles spin, but not the wheels. So, I took the wheels off to see what was up. The inner gear/cog of the bearing was spinning.
Now, I am not positive on how the hubs work, but from looking at it (maybe I'm wrong and someone can correct me), but their are two gears in the wheel bearing. The outer one spins with the wheel itself. The inner one is controlled by the axles, driveshaft, and transfer case. The purpose of the hub, is to relay the motion of the inner gear/cog and axle to the outer gear, and turn the wheel.

Now based on my observations, I'm assuming there must be something wrong with my automatic hubs, but they seem fine and my 4x4 worked fine before the new hub assembly was installed. I really don't want to go buy two hubs at $160 a piece or try to find one in a junkyard.

I've read from other sources about o-rings that keep contamination out. If contamination occurs, 4x4 could be lost. But I've also read that the hub Ford used starting 1994 doesn't have this o-ring. I don't know the validity of these sources and I haven't gotten to check the hub for an o-ring either, but it's a thought.

Any suggestions??

not sure of the exact production date of your Ranger, but my software says it has vacuum operated auto locking hubs. If that is the case, be sure the vacuum lines are good to the actuator and that they are getting vacuum signal when you shift to 4wd.

The door jam sticker says the truck was build in February 1999. Does that help?

Also, what other types of four wheel drive actuators. are there? I'm not sure, but I don't think mine has vacuum lines (haven't gotten to look yet because of the crappy weather). And if it isn't vacuum actuated, what do you think the problem could be (besides the hubs because I am pretty sure they are fine)?

Im pretty sure it is the hubs, since the front driveshaft is turning, and it worked before they were replaced

I have a 1999 Ford Ranger FX4 4WD and it has just over 96,000 miles. My 4WD doesn't work anymore. At first, it wouldn't work sometimes, i'd have to try a few times. Then it got worse and it would hardly ever engage. Now it won't engage at all. I've only ever used the 4WD for driving in the snow and I do NOT beat on it. The 4WD light comes on in the cab when i flip the switch and nothing happens. The last time i did get it to work, when i turned it off, it had trouble disengaging and made a loud "thud" when i was going down the road.

My terminology may be off. But isn't the hub the outer piece (which on non-auto locking ones is the piece that has knob that needs to be twisted)? (Noted '2' in picture)If so, it wasn't the hubs that were replaced. I replaced the hub assembly (noted as '1' in the picture). So considering that the 4x4 worked before the hub assemblies were installed - it makes sense that they would be the problem and maybe they are. But, with the truck in the air and the wheel off, spinning the drive shaft spins the inner gear on the hub assembly. Should it? Should is spin the outer gear as well?

It has a vacuum system. At the hubs there is a vacuum tube that comes out. There is a rubber line that goes onto it. I have seen them leak heare. Clean the tube, put some silicone on it and slide the rubber tube back on.

So the front inner spline is spinning, but the hub assembly wont lock the wheel in?I just want to be sure that the front diff is working and this is a hub problem.Have you looked to see about the vacuum lines? Im pretty sure the wheel has to able to roll to make the outer gear engage

[quote:735aa34229="thayersteraker"]Drive Train Axles Bearings problem
1999 Ford Ranger 6 cyl Four Wheel Drive Manual 120000 miles

I had to replace the wheel bearings this summer (came with the whole hub assembly). Before I did that, my four wheel drive worked fine. I bought my wheel bearings from Ford, so they should be a perfect fit. Now, with winter snow, I turn the 4x4 on and my front wheels don't move. I've lifted the truck up and engaged four wheel, the front drive shaft and axles spin, but not the wheels. So, I took the wheels off to see what was up. The inner gear/cog of the bearing was spinning.
Now, I am not positive on how the hubs work, but from looking at it (maybe I'm wrong and someone can correct me), but their are two gears in the wheel bearing. The outer one spins with the wheel itself. The inner one is controlled by the axles, driveshaft, and transfer case. The purpose of the hub, is to relay the motion of the inner gear/cog and axle to the outer gear, and turn the wheel.

Now based on my observations, I'm assuming there must be something wrong with my automatic hubs, but they seem fine and my 4x4 worked fine before the new hub assembly was installed. I really don't want to go buy two hubs at $160 a piece or try to find one in a junkyard.

I've read from other sources about o-rings that keep contamination out. If contamination occurs, 4x4 could be lost. But I've also read that the hub Ford used starting 1994 doesn't have this o-ring. I don't know the validity of these sources and I haven't gotten to check the hub for an o-ring either, but it's a thought.

Any suggestions??[/quote:735aa34229]
I had the exact same problem with my 1999 ranger there two o rings that you need one go just behind the lock out the other seals on the in side of the hub this is what makes your vacum work call ford and tell them you need the o rings for your front hubs if they give you any trouble contact me and i will see if i can find the part number for those orings

the front wheels dont spin at all. i hear the on the fly 4x4 click in, but nothing else happens? any particular reason for this so a mechanic doesnt rip me off?

Sorry I've been incognito. I've been super busy and haven't even really gotten to look at the truck. Until this week.

So... there is line going into the axle that I assume is a vacuum line. Assuming it worked fine before, there is a problem in the hub - whether mechanical or pressure, I don't know.

PACGDC - you say there are TWO o-rings. I could only locate 1 (before I read your message). Since I didn't know about a second set when I bought the first set, I didn't ask about it. But the Ford Parts person had trouble locating the first - so I am unsure about the second. I am going to drive down there tomorrow and check.
This site directfordparts.com/ has the Ford parts listed. Maybe you can find the part number there before I go and buy new hubs. The picture I posted above is the best I can do from that website.

Also, in taking the hubs off w/o the special Ford tool, a couple of the little tabs broke off (the hub is held on only by the tabs and then the wheel covers the hub). I know the repair manual and ALLDATA suggest that that could cause the air leak. But it seems improbable to me. Any thoughts?

IF you hear the transfer case kick in, then you most likely have a vacuum leak at the front axle. That is where I would start.

Let me know if you have other questions.
Joe

Just like PACGDC said, there are TWO o-rings. Lovely for Ford to help me out with that. I went in there specifically asking for the o-rings - it took them like 25 minutes to find it.

And it only took about 4 hours to jack one wheel up at a time and replace them - I hate those snap rings they have on there. Those are a pain to get off!

Thanks all! (I love 4x4 in New England)

It sounds like a pain but I had the same problem and instead of buying the expensive hubs I bought the rough ridge manual locking hubs they are only like $150 for the set of two, you can find them by searching them on google, good luck

the dome light quit working and the electronic shift control for the 4x4 stopped working also,everytime i replace the fuse it keeps blowing it.

You have a dead short causing this. What I recommend is disconnecting the 4wd actuator at the transfercase to see if the fuse still blows. If it doesn't there is a problem with the wiring to it or a problem with the actuator itself. Let me know what you find.

Joe

found the problem was a relay up under the dash causing the problem in a little black box taped up

went to autozone picked up a new relay everything is working fine now,thanks for the help.

I'm glad you found the problem. Let us know if you have questions in the future.

I have a 99 Ford Ranger XLT 4.0L. I turned my switch to 4wHi and I can hear it engage and my front drive shaft turns but the front wheels do not pull. When I turn the switch off the front drive shaft stops turning. The other day when I turned the switch it almost sounded like a "ratcheting" sound which I am assuming were the auto locking hubs. I am just not 100% sure what it may be. Any help is greatly appreciated. Thank You

Check the front axle 4wd actuator. If it is working, chances are the auto hubs need cleaned and serviced.

1999 Ford Ranger mileage: 54,000. I am having trouble engaging the 4x4 wheel drive. When I press the 4x4 button, I hear a tick, tick, and tick from the computer behind the drivers seat, hidden behind the jump seat. I hit the reset button and that got the light that tells you the 4x4 is engaged to come on but the wheel did not engage and pull when I spun the back wheels. I reset the computer again and again but the wheel never engaged.

Try replacing the engagement motor on the transfer case

99 ford ranger 4x4 auto tran with turn **** switch for engaging 4x4 when i switch from 2wd to 4wd the lights on the dash come on but the wheels never engage or does kick in. no sound. what should check to fix this

Check the actuator on the transfer case. It is common for them to go bad.

I have a 1999 Ford Ranger 4wd will not work sometimes it engages and some times it won't also the 4wd and 2wd light in dash will blink 6 times how do I fix this?

if this was a constant problem I would say it is your front hubs. 98 and 99 have PVH that breaks quite often. Mostly a vacuum leak from one of multiple locations, 1) the o-ring seal on the hub 2) the seal from the axle bearing to the interior of the axle 3) any of the vacuum lines running to the hub.

1999 Ford Ranger XLT 4x4 off-road 4.0L
When I engage the 4x4 through the electronic switch the electric motor on the transfer case DOES engage the 4H and 4L, I know the electric selinoid is working, however I do not get any power to the front wheels. I notice a metal on metal scraping noise coming from under the vehicle, I can't tell if its coming from the transfer case or the front end of the vehicle. I used the 4x4 all winter and at some point it stopped working, I am not just sure when. All I know is that I have no power being tansfered to the front end and I have a scrapping noise. I had a vaccum leak repaired a few years back and I haven't had that kind of problem since.
Please provide suggestions.

Check the U-Joint...if it's good you need to look inside the pumpkin! Or pull the wheels off and check the cheap plastic stuff at the wheels!

"Check the U-Joint...if it's good you need to look inside the pumpkin! Or pull the wheels off and check the cheap plastic stuff at the wheels!" - Merlin2021

No offense Merlin, but if were a U-Joint wouldn't I hear metal scraping all the time? I only here metal on metal when i turn the 4H or 4L on. I can be driving in 2H perfectly with no noise or scraping sound and then switch to 4H(shift on the fly). Then I get no power to the front wheels and the scraping noise starts. Then I switch back to 2H(shift on the fly again) and the scraping noise stops and throughout the whole time I got no front end power.

I hope that this clearifies my situation a little better.

Thanks

Well if you read your post I could't tell....Did you look?

I'm sorry I haven't looked into the guts of it yet.
I was just trying to get an opinion on if someone thinks that it could be gummed up hubs or if the front drive axel could be broken some how, or other ideas. I will be looking into it this weekend.
I try to fix these things myself, but there is only so much you can get from a book or read off forums, so I thought that I should ask.

Look Steve if ANYTHING at the wheels is broken BOTH sides stop engaging! Try draining some oil out and check for metal...