I might add some LED lights someday on the truck someday. Was looking to see what kind of flasher that was on the truck. [Thermo. or electronic] There was flasher type noise on the big fuse panel on the left side wheel well [ under the hood], couldnt find the flasher, used one of those stethoscope type things. And there was flasher type sound coming out of the speaker on the door panel on the drivers side. Never did find the flasher. Sure seem like the main computer handles that circuit too. Must be computer generated. Sure hope the computer never goes bad. I have 100% confidence in the mechanical longevity of the truck, but am scared that the computer might fail someday. Home type desk top computers fail, they seem like they have a life span. Seems like if it does fail I might have to get a bank loan. Do any of you GM mechanics/technicians know where it is?