JD73

Answer is to get a dependable tire gauge and use that before attempting to get all 4 tpms to read accurately. They should be in the ballpark but it's a monitoring system to identify an inflation issue while driving.

My wife's Blazer did this and they replaced the whole shifter assembly. Two weeks later we had to take it back and found the battery was in need of replacement because it was affecting the backup camera which was having issues the first trip to the dealer. Check your battery if it is older than 3 years and make sure it isn't the culprit.