Hey guys,
I got a 91 W250(auto/gas) and my 4x4 engaged light is always on, is this common on these trucks and is it an easy fix? It has the lever to engage 4x4 and it is in the 2hi position, also the truck has auto hubs. The truck does not appear to be in 4wd but my gas mileage is pretty poor. any suggestions?

 

Does it have auto hubs or vacuum engaged front axles? Auto hubs are screwed onto the spindle and vacuum has a solid friction fit chrome cap with no screws out at the end of the spindle. Another way to tell is to look at the axle tube under the drivers feet. There will be a solid axle tube from pumpkin to steering knuckle if it has auto hubs. There will be a vacuum actuator there with 2 wires and two vacuum lines if it is vacuum actuated.

 

Seal, It looks like its the vacuum actuated hubs. I haven't dedicated any time to look at it closely (been busy riding the motorcycle and working) but by your description it sure sounds like the vacuum actuated. Any idea where to start looking for my problem, TIA for you help!

 

The vacuum actuated locking axle is the Dana 44 axle. The problem could be a lot of things but most likely will be a bad diaphragm in the vacuum motor. This is easy to check. Jack the left front tire off the ground and try to turn it. If you can't then the axles are locked. There are 2 vacuum lines on the vacuum motor side by side. Use a vacuum source to apply vacuum to the drivers side vacuum port and see if it holds the vacuum. If not the diaphragm is bad. If it holds the vacuum you should be able to turn the tire now as the axles should have unlocked. Let me know what you find and we can do more trouble shooting if needed. New vacuum motors are available and there are other options also. DO NOT GO TO THE DEALER!!!!!!!!!!!

 

You could reverse the vac lines to see if the light goes off. May have a stuck vaccum switch. That is common and the switch on ebay is $7.50 I replaced the actuator motor, vac switch and all vaccum lines which had several holes. If your light is always on I would think you are always pulling vaccum leading me to think its not the actuator but the switch. Leaking vaccum hoses will also cause poor performance.

 

It will be a couple of days before I can take a look at it as I'm heading out of town on a coal train. I'll try and tackle it Monday, don't worry about it going to a dealer we haven't had one here in town for at least 5 years! Thanks Seal, and pickerbush I'll let you know what I find out.

 

I got the truck checked today, both front wheels spin freely. Any suggestions from there Seal? Also do you think I'm damaging the truck driving it this way? I've been driving it this way for a little while now?

 

upon further review it appears the switch that controls the light (opposite the 4x4 actuator) is no good. Tested it on the ohm meter and it appears to be not working. Hopefully this is my problem.