So all the sudden Im getting awful fuel mileage and I can't figure it out but then I have a break through..... When I park the truck for the night the trip meter says I went 64 miles and used 3/4 of a tank (I reset every fill up). I get back in the next morning now the trip meter say 51 miles. How could it be going backwards? The odometer goes backwards too. I had 177699.9 on the clock when I went to work and 177699.6 when I came home. I know it works and is accurate while driving, I saw the odometer turn 177700.0 with my own eyes. Any ideas how my truck could be setting it self to less mileage while off and parked?