allison trans problem


New Member
Mr.AllisonMan, Have a 2003 GMC 2500 HD Duromax with Allison Trans.47000 miles
3 weeks ago parked truck and shut engine off. Approx, 10 minutes later started truck and put in reverse, it clunked and made noises like the trans was ready to drop out. I than put it in drive,same thing happened. I turned the engine off, waited about half minute and started truck. It made same noise but did back up, put in drive and started to slip in drive. I shut engine down again ,waited and put back in drive, proceeded down road in drive wouldn't shift out of low . I went approx 5 miles in low to get to my camp. I shut down again, waited a few minutes started back up this time it would not move in drive or reverse. Called towing service they came , I had to start truck back up to move it to a position where they could hook it up. I told tow driver it wouldn't move when I tried about hour before. Well I started truck put in gear and it backed up okay. Had towed to dealer ship. That was on Saturday, Monday morning called dealership they said we started truck and it ran fine all gears worked fine ,for me to call back later. I called back few hours later they put 20 or so miles on truck (no problems with trans). Forgot to mention (check engine light) did come on when this all started and stayed on. They could not find noththing wrong, since than I have put on approx 1000 miles and towed a 8000lb boat and trailor 200 miles, no problems. Can you help out??? I do not want another breakdown ,which at that time was 200 miles from home and costly for me thanks, Bill