'03 EXPY checking it over and doing pm I discovered the transfer case would not shift into 4 wheel high, it will shift into 4 wheel low??

 

Look's like the transfer case gears engage but the light doesn't turn on.
The light does work as it lights up at start up time.

Also the front hubs don't dis-engage when switched to 2 wheel drive.

 

Welcome GLong! The expy doesn't have hubs that engage or disengage, the axle shafts are tied to the differential at all times.

I can't however explain why you get 4Lo and not 4Hi.

 

It's my understanding that the hubs do dis-connect, there are two vacuum lines to each hub, one engages the other dis-engages or one engages the other is a vent to the back side of the vacuum diaphram. 2 wheel high should dis-engage the whole front end.

 

Relpaced the electrical controlled vacum switch to the front hubs, this seems to have fixed the problem.

The hubs unlock, the driveshaft disconnects, and the 4WH light turns on while in 4 wheel drive.
The switch is located beside the battery box.

 

glong15650, the part you replaced is that a Ford replacement part? How much is the part? Can you give a better description of what it looks like?

 

I had the Ford garage do a computer scan for me and they indicated that it was the vacuum switch causing the problem, they charged $87 for the diagnostic.

The switch cost $56 and it was a Ford item. (part # 6L3Z 9H465 B :valve asy)

The switch has two vacuum hose's one going to the front hubs and the other to a vacuum connection on the engine.

There is also an electrical connection with two wires that control the switch.

It's easy to replace, it slides into a bracket on the firewall beside the battery.

I hope this will help.