When it's cold, let's say 15 degrees of colder, and the truck has been sitting out (end of the work day) I get a random, quick flash of the parking brake light, the PRND21 brightens up, and the RPMs do a small bounce. It seems to do it once then not again until another cold start.

Everything I've searched comes up with the usual grid heater cycling behavior. But that isn't it. Don't recall having this issue last winter, or I never caught it since it's quick. I was able to find a clip on youtube of exactly what mine does, but can't backtrack from it to see any resolution of that owner.

Anyone experience this? I've cleaned my battery posts in December. Was going to double check chassis ground. Also, no codes are showing up.

Here is exactly what happens to mine....

 

Get a digital voltmeter that plugs into the cigarette lighter plug and monitor the voltages since the IP voltmeter is worthless. Doesn't seem out of the normal with the heater grids cycling. How old are the batteries?