If you are getting 14v when testing from wide/parallel side bus bar, then you should be able to move one lead of the multimeter towards the center of the parallel line, you should see the voltage drop by about half, so around 7v.
If you drag one to the center, or close to it, and see it shoot back to 14v, then the break is in-between your two multimeter leads.
Have you tried leaving the grid powered off, and using your multimeter set to ohms to try to chase the grids to see any big resistance changes?
I've never tested mine, but I'd be willing to test how the ohms change on my grid which all works fine.
2006 Pontiac Grand Prix GT with SC
1996 Buick Park Ave NA