Possible Parasitic Power Drain or Ground Problem

[Joseph P]

I'm thinking I might have a double trouble of both a grounding problem and a power drain. I've checked the battery, takes a new load into the 14's, so it's ok.
I'm hoping one of these clues rings a bell for someone that recognizes what may be a standard problem here:
2003 Tahoe:
-at first, seat heat would come on haphazardly. Disconnected couplers under driver’s seat, problem solved, but no more seat heat of course.
-later, instrument cluster lights up on and off like a xmas tree when driving, accompanied by a relay click click sound located just below where the left side panel switch controls are (probably the seat heat relay) simultaneously turning on and off the seat warmer light buttons located on driver side door.
-tachometer/info display (long strip at the bottom, green led's) comes on and stays on when vehicle is off thus draining the battery over about four or five days. Opening the door/grabbing the handle turns it off, but then comes back on a little while later after shutting the door.

I hope I am being clear here. Trying to be succinct. Thanks for reading.

 

[MassHoe04]

The grounds at the driver's side front body mount play an important part in the behavior of systems controlled by the body control module (BCM). Pretty-much every control function and display in the cabin is controlled through the BCM. Including the items you listed.

Try cleaning the contact point and the terminal connectors on the ends of those wires. See if that does anything. Shoot some paint or prime over them after you have it all cleaned up and bolted back in (to protect from corrosion).

There is always a some chance issue could be in the BCM itself. But start with the things that will cost nothing and be easy to try before freaking out on more expensive possibilities...

Let us know what you find. Good luck!

Hopefully, it is not below 0 F like it is here...