Mopar ECU

The low coil voltage indicates either the bypass (IGN2) from the ignition switch has a problem or that something is dropping voltage TO the ign switch. This also might be (one of the usual suspects) ..............might be the bypass wire (usually brown) coming through the bulkhead

I'd check power TO the ign sw in 'crank' and power on the ign2 terminal at the ign switch

Be CERTAIN the ecu is grounded

Make certain the ECU is NOT hooked to the coil side of the ballast