Check Engine Light as Speeding Trigger?
I have a shortie built by MidBus (who no longer exists) on a Chevy Express 3500 platform. Since the day I drove it home, the Check Engine Light comes on at exactly 70mph. As you accelerate past 70, it flashes. Slow down and it stops. Do this enough times and the light will stay on for a day or two and then turn itself off. There doesn't seem to be any connection with RPM, just speed. Aside from the light, there's no signs of malfunction.
I've checked with code with a scanner and it's a generic "random misfire" code. I've replaced the spark plugs & wires, and the problem has persisted. I've basically ignored it because the engine isn't showing any actual signs of a problem, but I'm curious - is it possible that the computer was programmed to trigger the light when the driver goes above the highway speed limit?