I've check grounding everywhere. Body is grounded, engine block is grouned. The wiring is from a complete kit, Kwik wire. I switch the ignition on, the handeld boots up properly. But as soon as i start cranking it reboots. Discerning, especially since I try to reload parameters from scratch. I've had the system now for couple years, but it as always rebooted during startup. I have tried connecting direclty to the ECU (removed the extenstion) with no difference.