Im having trouble with this too, I hooked mine up, ground on bottom right. Power bottom left, and pcm to top left, using 12 ga. Wire to power and ground, something like 18 ga. For pcm. And when im doing 5 mph, it says im doin 100 mph, then of I go above 15 mph then its hitting the stopper on the 0 side, it still adds mile to the mile clock.. any help is appreciated