Heated seat issues.
 

2006 Hummer, just bought, tried heated seats, the lights blink, then immediately shut off. However if the heater is off, the lights stay illuminated. Very odd. I haven't had any time to look into yet, will this weekend, just thought I'd throw out what I know. Thanks in advance.

the issue is usually bad heaters in the seats. they are sewn into the leather and discontinued. if i remember a good seat heater element measures like 12 ohms

If its the rear seats there is a control relay in the back of the upper part of the seat. Remove the cover and you can get to it and unplug it. When I had my 06 my rear heaters would not work correctly. The control relay was the culprit. When I removed and disassembled the unit it was fried inside. It took me about 6 months to find a replacement.