Dash mounted 4wd switch not engaging

[LHMissions]

My '03 FX4 has the dash mounted switch. To engage 4wd, I have to get out and lock the hubs from AUTO to LOCK - the dash mounted switch does nothing.

Is there a fuse of something simply I need to fix? 4wd works great - just dont want to get muddy to engage.

[720Deere]

Either your vacuum pump is dead or most likely the seals in the axles are gone. Either way you're not getting vacuum to the auto hubs to engage them.

When you flip the dash switch, does your a/c automatically blow out of the defrost vents?

[LHMissions]

I dont think the AC blows out the defrost vents. I havnt noticed it to. I'll have to check.

[worx]

Does the transfer case go "clunk" when you flip the switch and the 4x4 light come on? Mine quit doing those when the wiring was not making contact after the tranny got rebuilt- seem they broke the retainer on teh connector... but might have gotten snagged and broke loose.
If they come on, and your heat/ A/C goes where ti should, you might need to clean the hubs- are they tight to turn or easy?

[LHMissions]

I'm pretty sure the AC goes where it should. I'll check at lunch.

The hubs are tight to turn manually.

What is the best way to clean the hubs?

[worx]

I can't find the link in the tech section right now, but I think it sent us to Guzzle's page with a step-by-stpe rebuild on the front auto-lock hubs- I am thinking mine might get this sometime this summer too...

The page is: Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page

Hope it helps!

[LHMissions]

Alright - I checked the AC vent issue last night - I was amazed to find that sure enough, when I switch to 4wd - the AC also switches from front dash to defrost vents!

What is the significance of this? Obviously something is wrong here. I also noticed it was difficult to get the AC to blow back out of the front dash vents - even after switching back to 2WD.

There is no clunk when switching to 4WD. Dash light shows 4WD - but no engagement. The only way I can get engagement is to manually lock the hubs.

What now?

[720Deere]

You have a vacuum leak between the pump and the hubs. Most likely the axle seals.

[Mudracer80]

mine does the same thing, were is the pump located? will the 4x4 still engage if you lock the hubs or is it useless until I find the leak?

I couldnt get mine to engage this weekend even with the hubs locked but I may have been doing it wrong or something.