AC controller issues

Ok, this is not a thread about the AC blower motor resistor, just to get that straight. I've got a 2014 SR5 and just recently the blower motor quit working, 3 weeks ago actually. Replaced the resistor because it was cheap and easy. There was no brown marks on the plug but replaced it anyway. No worky. Chased voltage all the way down to the plug on the back of the Blower switch unit on the dash. 13.5 volts with the motor running but no voltage after the control unit. The dealership wanted over 800.00 for the controller. I told the service/parts guy that " Its 3 switches with a copper trace board on the fan switch knob and its all made of plastic not gold!!" Anway bought a used one from Ebay for 130.00. Worked great, for one week. Again voltage at the Controller but nothing after that. Ordered another one from ebay for 88.00 and its working again. Plan on sending the first one back to the seller as he said he gave a 90 day warranty.

The back story is that not long before that all happened I had added an electric brake controller to the Taco. Maybe 3 weeks before the stock AC/FAN controller went out. the brake controller came with a pigtail that plugged directly into the Taco's available harness plug. So just for troubleshooting as of right now the brake controller is disconnected. Has anyone seen this type of issue? Maybe the second AC/Fan switch controller was just on its way out?