No engine service light comes except when cranking motor. Then , light goes out. Truck runs well, but I was just concerning if timing was advancing accordingly. A local shop, that I have done business for years, indicated that everything sounded OK. I searched the WWW. I could never find a ignition/distributor curve for a 1995 K 1500 either. I suspect that since the "brain" controls advance based on sensor inputs and engine load., it doesn't exist.

 

With a scanner check,you would see int,and blm, fuel trim,so with that and knock sensor counts,if low and stable,you could advance timing a bit,it's the fun stuff that's hidden

 

Somehow, timing was off. I readjusted timing. Years ago I may have used incorrect wire to set base. Retarded too much. Major difference now.

 

My intown gas mileage with AC ON went from 9 to 11 after I set base timing to 0. I don't know if I had adjusted timing incorrectly in the past or some mechanic incorrectly set it. I have owned truck since 2002. Computer may have been confused and would not advance spark or power. Truck performs much better, now.