I got a little 4x4 light on my dash that goes on win you engage 4x4 and the last couple times the light refuses to light up , any ideas what would cause this

 

Need more info.

Year and model truck
**** or lever shift
Does 4wd actually engage or not?
Are you trying to engage 4wd Low without foot on the brake and in neutral?

 

Its a 2007 F150 crew cab XLT and its a switch on the dash.
4x4 does work win I turn the switch to 4x4 low or high, I can also hear it engage. iv looked at all the wires under the truck and they seem to be in good shape.
No blown fuses that I can find, also win I start the truck it will flash on then back off. and win i turn the switch to engage 4x4 it does not flash for me.

 

Check the IWE vacuum solenoid under the hood on the passenger side firewall near the battery.

 

I checked the vacuum to the solenoid , its working good , no moisture or freezing going on, actuators are in gageing ok