Well go through and check every single coil with the DMM make sure they're all reading around whatever ohms they are. Like if its a 4 ohm sub it will not be exact it might read 3.8,3.9,4.0,4.1,4.2 you get the idea. You need to look for ir either not reading an ohm load or jumping numbers( like whole digits not points) That way you will know they all are working.