You are right. I have a 2014 SLT Sierra 1500 and i cannot find a good spot. Ass hurts on the very back part and legs tilted upwards. My legs get tired and have to stop every hour to move around. I heard its with leather seats. Im going with cloth seats.
I have same issue, no readings. I bought the tool and it wont reset. Maybe batteried are out on them. Honks twice and driver front marker lights on. I point tool and nada. I take air out and nada. No numbers on dash.