Automatic Transmission problems of the 2004 GMC Sierra

: the contact stated while driving in normal conditions, the transmission locked up. The vehicle was taken to the dealer several times for inspection. The dealer replaced the transmission; however, the new transmission has the same problem.

Automatic transmission would intermittently hesitate before catching in gear while driving. Vehicle has been to the dealer on two separated occasions and they were unable to duplicate the problem. Consumer was concerned that this vehicle maybe rear ended. The truck was on an incline in overdrive with my foot on the brake, let off the brake and gave it gas to merge into traffics and the truck wouldn't accelerate. It hesitated until felt like a gear caught and then into traffic instead of going when it needed to go. The second time was almost the same way.

Consumer and his wife were cleaning the vehicle. Husband was outside washing the vehicle, while the wife was inside the vehicle, cleaning. The wife had the key in the ignition, turned to accessories while listening to the radio, and accidentally pushing the shifter down with car being off and vehicle moved backward, hitting the husband and injuring his knees. The consumer entered a file # of 1-281746845.

Our son-in-law owns a 2004 GMC 4-door pickup. It has automatic transmission. Our two-year old grandson was in the truck while his father was cleaning it. The key was in the accessory position so they could listen to the radio. The child pulled the shift lever out of park and the truck ran away down an incline. Both driver's side doors were separated from the vehicle by a tree and the truck continued until rear-ending another tree. The child stayed in the vehicle and was unhurt. In checking this truck, our 2003 tahoe, and our 2003 Chevrolet pickup we find that all of them: 1. The shift lever is locked when the key is in the locked position 2. The shift lever is locked when in the "run" or ignition position and requires the brake to be depressed prior to shifting. 3. But in the "accessory" position the shift is completely unlocked and requires only a very slight pressure to move it out of park and result in a runaway. I feel there is no reason for the shift lever not to be locked in all positions and, in fact, the fact it is locked in two positions but not the accessory position results in confusion and a false sense of security. This was not a component failure, but is a design failure that apparently involves all gm trucks and suvs of this model.

Transmission makes a clunking sound when shifting from 2nd to 3rd gear. Also, intermittnet slipping of transmission when starting to move from a full stop. Vehicle hesitates before it begins to move. This occured within the 1st 500 miles and contines to occur today.