I cannot find the problem that's causing my turn signal/cruise control switch to go crazy at times. It's not multifunction switch, not a fuse, not control box (junction box).
So what can it be and how can I find the issue?
thanks

 

Not sure what you mean by going crazy, but a vehicle that I had once would make the turn signal flash very fast indicating that a light was out. Not sure if that applies to Suburbans or not.

 

I replaced every bulb in the car so this is not it

 

"Go crazy at times" isn't exactly specific enough for someone to even take an educated guess at the problem. Try being more descriptive as to the actual behavior.

 

interior lights flashing instead of turn signal operating
plus cruise control sometimes works and sometimes doesn't

 

Both issues share the same signal arm, but it may be two separate issues. Changing out the directional relay may fix the flashing issue, but the cruise control issue might be related to a problem in the signal arm itself. Youtube a video or two before you do anything, they have saved me a lot of money in the past.