Check Trans Light, Engine Won't Start
I have a 40' 2002 Thomas bus with a 5.9 Cummins Engine and an Allison transmission. I have a problem with the transmission right now. The problem is this: I drove the bus all around and it was great, for hundreds of miles. I parked it to begin my conversion and a couple weeks later I go to start it and a red "Check Trans" light comes on the dash, and the engine won't turn or start. If I turn the key, nothing happens. I do nothing about it for two weeks or so, then I turn the key one day and the engine starts and the light disappears. I drive it around for a couple of miles, then park it again. A week later, I turn the key again and the same check trans light comes on and the engine won't start.
I spoke to a mechanic the first time it acted up on me, and he thought that (maybe) the transmission computer was telling the engine computer that it wasn't in neutral. FYI, the electric display always shows up as "N" when I turn it on, indicating it is, in fact, in neutral. The mechanic suggested disconnecting the batteries for 15 minutes, then reconnecting them. He thought this might reset the computer. I did that, but it didn't do anything at the time.
Any other ideas? I've searched the forums but couldn't find anything. I remember seeing a post a while back about some magical combination of "N" and "D" button pushes that might reset it? Thanks a lot for your help guys!