We have a '09 Tahoe LT model. Last fall, while diving on the highway, it suddenly began to unlock and then lock the doors, dash lights flashing, transmission going into trailer/haul mode, all of this un commanded. It then ran normally and then the whole issue started all over again. It turned out that the battery had a broken post within the battery body, Intermittent continuity was to blame and once the battery was replaced the Tahoe ran normally throughout the winter months.
However, we were returning from town today and the symptoms started all over again. The battery was replaced last November and appears fine, my multimeter voltage shows 14V. I am baffled as to what is causing these issues. Save to say, I don't trust the Tahoe without getting to the bottom of this. I don't want to be stranded at the side of the highway.
Any ideas??
Bruce

 

Since you are in a salt zone check all the grounds. There are quite a few of them. All the black wires connected to the frame. Remove and clean. Multiple ground points are used to connect the many modules controlling the vehicle.
This is assuming the positive connections and battery is up to snuff. I've had multiple batteries in the last 15 yrs. do the same internal failure. 3 of them to be exact and all within warranty. I only use premium Odessey or batteries made by East Penn manufacturing now. Canada supply may be different.

 

It would seem the intermittent loss of POWER OR GROUND could be the source of the problem. The object now , is to find it