OK. Hummer H3 Adventure w/ auto tranny. 82K Miles. No previous issues, noises, problems, etc. Parked at Tractor Supply today, got back in and no reverse. Luckily I had no one parked in front of me. Shifted in all other gears except reverse. Park, OK. Neutral OK. Drive, 3, 2, 1 all OK. Shifted from both directions numerous times. No reverse. No noise from the tranny except when shifting into other gears. Nothing unusual or out of the ordinary. Drove it home. Pulled into driveway. Shifted to 4H. Shifted to reverse. IT WORKED. Went back to normal AWD. Reverse now works with no issues. Any idea what I may have going on?

Just purchased a radiator yesterday after I discovered a crack in the top as they all get. Haven't installed it yet. Went ahead and bought Dex VI and filter to do fluid change, and DexCool and new hoses for coolant change while I have everything apart.

Any input?

 

I should also mention that the doors unlocked in Park and locked in reverse and the backup lights came on. (Confirmed by passenger)

 

Linkage. There's a problem between your shifter and the tranny. Someone will give you a better answer tho. But I've had these transmissions go bad. 80,000 seems too low of milage and they do give you some notice first.

 

? WhAt happened

 

My transmission stop to work well when I had less than 125,000 km on my 2007 H3. After that truck still was running, but it took so much time to drive through 1 and 2- d gears. My wife was driving H3 during that time and she said it didn't give any previous unusual sighs or noises before it happened. And when I changed my parking spot on our driveway I felt that something wrong with a transmission. Still I don't know why it happened with it with this relatively low mileage?