I just turned over 100k miles
The GF turned on the Heated seat in the pass side. We thought we smelled something burning. but forgot about it, it was late.
Next day the battery was dead. Got the Blazer started, went to work, in 4 hours - dead batt.
got home and put on charger.
Found out it was the heated seat. The truck was turned off and the seat is still heating?
PULLED the fuse, everything is nornal with charging system
Is there a Relay for the heated seats? I thought with the seat belt out-it would not heat?
also thought when the Blazer is not running - the heated seats didn't work?

Ken

 

Sounds like something has shorted to +12V in the switch or harness. Is it just the passenger seat that is doing this?

Here are the wiring schematics:

 

Yes, passenger seat
Is it normal for the seat heater to be on when the Blazer on off?
When it warms up I guess I could start with replacing the switch

 

No, this is not normal. The switch is powered by a circuit that is "hot in RUN" as the attached wiring schematics above show.

I would test the main power wire to the switch to make sure that it is not getting power when the key is off. Then test the line from the switch to the passenger heated seat module (under the seat) for +12V when the key is off. If neither of these are getting power when the key is off, then the heated seat module is bad. That would be my guess.