05 Sierra Trans Problem

[88m53453]

05 Sierra 77,000 miles, clean fluid, level fine, Went thru a driving rain storm. To start with. it began to upshift when the accelerator was depressed an would down shift when coasting. This went on till I stopped for a light and then it was fine, until.... We had dinner and came back out an hour or so and on the trip home, It began to slip witn any more than light throttle. Stopped again to visit friends for about 45 minutes and all has been well since. Is there a service notice anywhere about water proofing the pcm or wiring ? Or am I totally off on that conclusion ?

thanks for any help

[88m53453]

anyone ?

[Draenor]

I think you just need to have the PCM re-flashed and updated.

[88m53453]

that doesn't add up as it only did it after the heavy rain