I have a 02 with Allison auto. Problem is sometimes when i put it in Reverse the Shift Indicator Flashes and the Service Engine Light comes on and it does not go into Gear. I have all other gears and tranny shifts fine. I have read the code. It Says "Tourque Converter Clutch Solenoid Circuit Electrical". I have seen on other posts at Diesel Place that this is also what happens when the NSBU goes bad. Can this code be caused by the NSBU?

Yes could be. Does this happen after it sits for a length of time?

My '02 used to have that problem too, but in my case, after I went to a deep pan and TranSynd, I don't have the problem anymore. Hope this helps...

I drove it about 10 miles had reverse when I started. Stoped for about 15 min. then no Reverse