if it wont crank with the key then I'd get fire to the "ign" terminal on the starter relay from the yellow wire plugged into that terminal and check that the "grn" terminal next to it on the starter relay is being grounded in park/neutral (not sure which circuit the seat belt interlock interupts). If it cranks but wont start the coil positive primary terminal and the ECU power wire both need fire in "ign2", the brown wire ballast bypass circuit & if not see whare the open is