M1078 hard shift

[GeneralDisorder]

Another side question here, I checked my codes and I have only 2 showing, a "power interruption" (from the previous brownout, and a "ECU high input voltage" (presumably from the same outage). Thing is, I have an intermittent issue where on downhills (again when it's cold) the trans downshifts 1 gear from 7 to 6 rather hard, then displays "check trans". My foot is off the throttle at this point bc I'm rolling down a 6% grade. But when I pull over and come to full stop the light goes away and the trans feels like it shifts, then the display goes back to 7 and all is well for the rest of the ride.
I tried it again yesterday to see if I could repeat the issue but it did not exhibit the problem however I had already done the "rapid warm up" procedure so the trans was probably warm.
I've only had this happen 2x and both times the trans was cold (ie no warm up procedure).

Clean all the electrical connectors to the transmission with Deoxit.

You need the Allison DOC software hooked up or something like a DPA 4/5 or the BlueFire J1939 to be able to scan for codes in real time while you are driving so you can see what the TCM is complaining about. Need to know what voltage the TCM is seeing..... when I had an Over-Voltage Cut-Out (OVCO) happening with my truck the TCM was the first to complain with a Check Trans light. The TCM is very sensitive to input voltage and is often the first thing to be damaged due to incorrect voltages.