My sister's husband and I went through something similar when we were wiring up the convertible he's building for her. It was the chassis ground. Remember, there's an engine AND chassis ground, make sure both are connected. Also, the ground MUST NOT be contacting any paint AT ALL. It will not properly ground, if at all. Check them, insure proper ground, then try again.
In such a world as this does one dare to think for himself?
The paradox of power and peace will destroy itself.