4wd issues 2003 silverado LT
 

Hi Last night we had out first sloppy weather of the season here on Long Island. The switch seems a little erratic and sometimes it works fast or slow and other times I can hear it shift into gear and others not, No warning or Check engine light, I'm not even sure if there should be one. I found the only fuse and its good. I used my scanner on it and no codes. its the first time I ever had a 4wd issue all my years with Chevy trucks. I will have a new switch here tomorrow, was a good deal. I hope its the problem but I have my doubts. I was having electrical issues a couple months ago and hope its not that again. any Ideas? also what's a good way I can be 100 % sure its out?

one other issue that may be related. I had a u joint go bad. after the repair. the joint fell apart same day 2 blocks from shop.
I managed to get the truck to the shop using front tires. so it was working then. I noticed today that when I push the button in neutral to go into 4w hi or low I have to come to a full stop for it to shift over.
another thing if I drive in 4w low and shift to 1 the truck is very jerky don't seem right. I cleaned the grounds under drivers door.

Not sure what this new switch will do?

again I get no codes or dash light telling me I have 4wd issues.

If I block the rear tires and put it in 4wd lo or hi and lift the front end. If the front tires move am I ok?

I'm lost here.