I just received my Nanocom a few days ago, used it to reprogram a key fob, played around with the different diagnostics, powered Nanocom off, but left it connected to the OBD2 port. I cranked up my truck today and suddenly this awful grinding noise started, I turned the key off, and the grinding was coming from the viscous fan, which continued to spin the belt for another 20 seconds or so after the key was off. I tried to turn Nanocom on with KOEO, but it didn’t power on. Multimeter read 9.6v at the battery. I hooked up a jumpbox and everything started up fine, with the only fault being a low voltage fault. My fan doesn’t spin free when moved by hand, but I can move it with little effort. Not sure if this is a secondary issue, but it did make an awful grinding noise on the 9.6v battery, but was fine once jumped off.

Does Nanocom draw power if connected with the key off? If not, are there any other systems that may have been activated when I was using the Nanocom that would drain the battery that much in less than 48 hours? Thanks I’m advance.

 

Sounds like 2 different issues to me. The viscous coupling should not spin freely when the motor is turned off. If it does then you need a new viscous coupling. Not sure about the grinding noise though.

I always unplug my OBD2 reader when the truck is turned off to eliminate any drain via the OBD2 port.

Good luck and let us know what you find.

 

Since the nanocom works with ignition off, it drains the battery when connected.

One day I forgot to take the ignition key out of the cylinder (ignition off) and the next day the battery was down so I could not crank.

9.6V damaged your battery. Never go below 10.5V.

 

Update:
When I put the multimeter on the battery this morning, it was 12.25v, so it must have been the Nanocom being hooked up previously that was draining the battery. Still not sure what made the fan make that grinding noise and continue to spin after the key was turned off, but I already had a Hayden 2991 clutch and Dorman 620-112 fan on order anyway, so it’s coming out soon. I also plan on doing a dual battery setup soon. Thanks for the replies.

 

The Hayden/Dorman set-up is the way to go for sure!