New to site looking for a bit of assistance. I have an 06 GMC LBZ/ 6speed Allison combo that is giving me the fits. After normal stop and go driving for a half hour, I am getting shift range inhibit while driving slow 10-15 mph. First and second gear just off idle to 1200 rpm, Trans temp- 150-170. When this happens truck flashes gear selection, dic say shift range inhibited. If I select M the gear shift it indicators 5 until the trans shifts to 1 or 2 depending on the speed at the time of inhibit. I have also experienced this while driving at 60 over 40 minutes. Then randomly neutral, shift range inhibited, and a loud clunking noise. Again by pulling the gear shift to M, letting off the gas the trans will shift back into gear. No check engine light. To my knowledge no codes. Any ideas? I am not reading any other threads with similar symptoms. Trans seems to be operating normally other then this. Fluid is full. Ideas?
