battery fan intermittently dropping voltage

Has anyone had any problems with the battery fan intermittently dropping out almost completely? It's dropping voltage when I do a fan test on techstream and it's driving me nuts. I'm just about to call it a faulty vci cable or connection. I'm just not sure exactly how the techstream activates those tests and powers the fan up.

With the harness unplugged from the fan I get a steady 13v supply, uninterrupted. But when I connect it to the fan, it runs for maybe a minute or less and randomly slows way down. It stays like that for a bit, random times, and goes right back to full blast. And over and over and over again!

I've taken the fan apart and cleaned it and checked the brushes. I've wiggled every wire and connector within reach. I even swapped the battery ecu. Still the same. The puzzling thing is that the last 1st gen I tested the fan on did the exact same thing, only I didn't spend 2 days trying to pinpoint the problem.

Could it be my vci cable or something screwy going on with techstream? I tried to purchase a 2 day pass for TIS and couldn't get in to my account and got a warning about their security certificate, said it was not a secure connection. If my hair was any longer, I'd have it pulled out by now!