1998 F-250 4x4 Troubles......
 

Ok, so I bought this 1998 F-250 XLT rust bucket without really having the time to properly go over it and nowhere to test drive it so when I got it home and pulled it into my front yard I immediately got stuck because the 4x4 doesn't engage even though the dash lights up, shame on me!! I've had older 80's GM 4x4 trucks with no problems and easy repair being as they atleast had a hub to diagnose....... This truck has no "hubs" I can replace or check out so I assume I need to start with the Transfer Case shift motor being as I have already checked the 2 fuses out, 1 under the dash the other under the hood. I understand that there is also a "vacuum actuator" attached to the front differential. So can somebody tell me what and how to try and diagnose this $3400 lawn ornament? I would greatly appreciate it...........

I realize this is primarily an F150 forum but I figure the 4x4 systems are more then likely similar.....

1998 F-250 XLT Extended Cab 3 Door
This IS an F-250 "light duty" - Exact same body style as the 97-03 F-150....
5.4L
ESOF 4x4
Automatic Trans.


Thanks

Is this a F-250 "light duty" - exact same body style as the 97-03 F-150? If so, it's the same front drive system.

Start with the real simple obvious stuff - does it have a front driveshaft?

In addition to the transfer case shift motor, it has a shift fork to lock the diff in - that can freeze or break.

Well I think I figured the problem out, I believe it is the 4 by 4 vacuum solenoid because I have no vacuum down at the actuator that is on the front drive shaft when I switch the vehicle into 4 wheel drive but I do have vacuum when switching back to two wheel drive so if my assumption is correct it is indeed one of the other famous problems for Ford and that would be the vacuum solenoid...... And by the way, yes the transfer case switch motor is working fine, or so it would seem.