Have a unit with 2.4 GM engine with no start. Has no power to coil pack or lock off during crank. Also starter kicks in and out. Power comes on when key released from crank position for a millisecond. Tech from Tennant diagnosed as coil pack. Replaced coil pack and same problem. I suspect either ignition circuit or ECU but don't have section 3 of service manual for troubleshooting. Any help would be appreciated.