Hi everyone!

I'm new to this forum () and could use some help with a problem I'm having with my truck.

It's a 2001 crew cab, lwb, automatic tranny, 7.3L, 3" lift with around 150,000 miles.

I bought this truck about a year ago, and it has had a few little issues along the way, but this one has me a little stumped.

The 4WD will not engage at all when the switch on the dash is turned on.

The trouble shooting that has been done so far is...

Check the vacuum lines
Replaced the dash switch
Replaced the actuator motor

None of these seem to have been the fix, so what next????

If I left anything else out that would help, I appolgize.
Any and all help is greatly appreciated,
Scotty

 

My thought would be the vacuum pump. It's a little windshield washer pump looking thing on the passenger side wheel well. If it goes, it usually does this, and a lot of the time it will leave your climate control stuck on defrost too. See if it is constantly running or not running at all, either of these and it needs replaced.

 

Hey Scott, welcome to FTE. Glad to have you as a member here.

Wondering if there is a fuse for that? I do not have my book here with me but maybe someone else will chime in.

Can we eliminate the simple? Meaning, trans in neutral and foot on brake when engaging?

 

It could be something as simple as checking the fuses. Also try to manually lock your hubs and see if that helps. Also, can you hear it engage at the transfer case. To check, have you drivers side door open, turn your key on. Do not start the truck. Then turn the dial to 4x4 and listen for the transfer case to engage. Do all these things and let us know what happens. Someone on here will help you figure it out.

 

Thanks for the Welcome and advice guys!!!

Joe...
I'll look for that pump and check it out. The climate controls are working fine though, but that doesn't mean that the pump is working. Thanks!


Scott...
Yeah, I'm good about not doing the simple and going straight to the idiot! But, on this occassion, I have checked that already. This problem has been going on for several months now, and I have "tried" to rule those type of things out, but still good advice. Like I said, zero to Idiot in 1.2 seconds flat. DUhhh!!! LOL!

Jamie,
I can't hear the t-case engae at all, but I haven't tried it the way you mentioned. So, I'll do that this evening when I get home.
Fuses have been checked and are all ok.
And as far as manual locking the hubs, that might very well be one of those "simple" things I need to go back and re-check. Seems like that has been done, but I'll recheck and see what happens.

 

Check the vacuum lines where they plug into the hubs. Mine were cracked and causing a vacuum leak.

 

Scotty, Try this, start truck, put ac, or heater on front vent. With vent blowing turn auto switch to 4x4 give it a little time. If vents don't default to defrost, you don't have a vacuum leak.

Do as said before,stand outside the truck drivers door, turn key to on position, do not crank truck, turn switch to 4x4. You should hear the motor on transfer case shifting the transfer case to 4x4. I can hear mine very well doing this. If you hear the motor, I would look at the solenoid for the front hubs. Its located on the passerger fender wall next to the battery. Make sure the plug is in good. Get a tester, pull the plug and see if the center wire in the plug has power. The center wire is the only one that should have power with everything off.

There are lots of things to check, but need to discount one at a time. I will not be here after 5:00 but will check this thread in the morning. Don't worry, you can get this working by checking everything.

EDIT: Welcome to FTE.

 

The lines look ok, as far as cracking goes, but we're going back with a vacuum tester and trying that again, and then we'll check for that pump too.

Went back and the switch is getting power, the fuses look good.

Just crious, is there a computer link to this system?

The truck doesn't seem to be throwing a code, but wasn't sure if this system might effect it also.

Rick...
Haven't checked the selonoid, so will do that as well. Thanks for the tips.

I'll try and go through and recheck everything as mentioned. I'm sure it's something simple, just seems to be evasive, what ever it is.

 

OK, more info to this point...

Everything from the motor at the t-case forward to the wheels seems to be functional. The truck has functioning 4WD when the wire to the t-case is bypassed. We can engage the system at the motor putting a different power source to it. This engages the vacuum system, which engages the hubs, and front wheel turn. So vacuum system and mechanical componets for drive train are good.

Now,
The switch on the dash is getting power to it, but will not engage the motor at the t-case. The fuses are good. The selonoids are functioning.

What can malfunction from the switch on the dash to the motor on the t-case, besides the fuses and the selonoids, and cause the motor to not activate the t-case?

Again, I apologize for the ramblings and do appreciate all the advice being offered. Wouldn't be suprised if I get the boot after this thread is finished. LOL!!

 

What I would check for now is continuity between the ouput side of the switch and the egagement motor. I know you checked the fuses but there are relays involved as well. Look in your owners manual for those relays in the fusing section.

 

I second what Robin said. Take a volt meter and check for continuity.

Also, have no fear. You won't get booted from here. We are all learning from this and we are glad you are here. Some day one of us might have this same problem you are having. If so then we have this thread to reference back here.

One word of warning though, hanging around here too much can get expensive.

 

The 4x4 switch most likely supplies power to operate a relay and the relay supplies power to the egagement motor.

Check the ESOF Relays at bottom of this chart:

 

when my 4wd didnt work it was cause of the seal in the axle/hub area. i bought a mightyvac vacuum pump to see if the hub would hold a vacuum. the one side didnt. i had to go to the ford garage to get the seal no one esle could get it for me. all the seals to to the job cost me less than 100 to do for one side. i was able to do the job my self but it was a pain getting the new seal on

 

Sounds like you are getting close to running this one down, that is great. I love these forums too!

Just in case it turns out to be a hub sealing issue though, there are instructions on replacing the hub seals as well as the seals behind the needle bearings here: (I need to do these myself!)
http://guzzle.rbmicro.com/maint.html

Darren

 

Robin,
Thanks for the tips and advice. I think you exactly dead on about the 2 posts you sent. I'll check both and report back tomorrow morning.

Darren,
I also hope your right in that we're getting close to figuring it out becasue I'm getting this big headache for some reason...

lol

I was thinking about this, but when we rechecked today, everything from the motor on the t-case forward to wheels is actually functioning correctly. It just seems like it electrical from the switch to the motor somewhere. Anyway, thanks for sharing your thoughts and if these electrical gremlins don't pan out, I'll head back down this path.

Not to highjack my own thread too much, but I hear ya about expensive, Outlaw! I have a couple other money pits that get a lot of my back pocket. The 4X4 thing bit hard when it bit me. A '71 Chevy swb 4x4 and a '99 TJ that's not much Jeep, but all rock crawler now. The Ford is my DD and tow rig for these others. I've tried to help this Ford out with a few upgrades, but you know how that goes. Change one thing and 3 other things need to get upgraded also. LOL!

BTW, I'm from your part of Texas. I live in Point Aquarius in Willis and work up in Huntsville. I love hangin out at Papa's on Lake Conroe. Where do you live?

OK, sorry! Back to the thread.