low range light? ??

[deer_slayer09]

I got a 94 f350 with the 7.3l idi turbo and e40d automatic tranny. The truck is a 2wd. Ive been noticing the past couple of days that the low range light in the dash is blinking in and out, as if something is shorting out. I didnt think nothing of it until today. It starts rainin real hard and now the light stays on and its like the tranny only has 3rd gear and up. If i start out in first and manually shift it up it shifts fine. Kinda got me baffled here

Also, im pretty sure my vacuum pump went out, cause i hardly have any brakes and the a/c only blows out the defrost vents. Dunno if that has anything to do with it.

I just installed boost, pyro and tranny gauges.

Any help is appreciated