I have a 2000 Blazer that for the past year has bad some battery draining issues.

At first the battery would be dead after about 5 days of not starting the car. Eventually it shortened down to about 3 days.

After this I decided to try and hunt down the problem. I found that when I unplugged the TBC fuse in the main fuse box under the hood there was no more drain on the battery.

Now it is 6 weeks later and I have to start my Blazer every day and run it for approx. 30 mins or the battery dies.

Any ideas what might be causing this?

 

Normal batteries do not like to be fully discharged repeatedly. My guess would be that the battery has been damaged by the frequent drain down and needs to be replaced.

 

Sorry I forgot to mention that I have had my battery (approx. 18 months old) and alternator checked by two separate shops and both said the battery and alternator checked out fine.

 

Sounds like the TBC fuse wasn't responsible for all of the excessive draw on the battery.

You shouldn't have more than 35mA (0.035A) draw on the battery once everything has gone to its low power state (~5 minutes after you turn the truck off and close the doors).