You have a problem with the circuit or you are not checking it right. Full battery voltage on the negative side means that there is an open circuit/ loss of connection from coil negative to the module and possibly ground.
Unplug the ICM connector and with the key in run check for voltage at the pin for the negative coil wire. You should have 12 volts there, because you just created an open circuit at the connector, but because it's giving full battery voltage, that means that there is no break in the wire from the coil to the ICM.
