4wd

I have a '96 3/4 ton suburban and the electronic 4wd is not working.
The lights on both the 4hi and 4lo buttons stay on all the time and the 2hi light is not on and I am in 2hi. It won't shift into 4-wheel when I try but the relay under the dash clicks like it is trying. Sounds electrical but is it the switches themselves, the relay, a short??? Help!! Wanted some
input before messing with it. Thanks.