The Check Engine, Check Trans, and stop engine lights all work upon turning on the switch. My code switch is beside the lights. There just wasn't any codes. The mechanic was also surprised there were no codes. I believe the system is working. I also don't leave home without my DDEC II manual. The only explanination that I can come up with is the connections were not completely open, just high resistive. I'm just glad to be home until next year.