My vehicle is a 99 jimmy with 4 button system.
Ok here is what happens, the truck starts out in 2hi I press the 4hi button, I hear a click from the computer on the right side, now the 4hi button continues to blink, it will continue to blink never switching back to 2hi, now if I press the 4lo button the 4hi will stay on and the 4lo will come on, but when I put it in gear only the rear end is in 4lo, the back tires will spin in 4 lo but the front end has no power.
It is as if the valve in the front under the battery box isnt working or I have a vaccum leak. Any suggestions?