I have a Allison in a 2007 Navistar 3200 transit bus. Simply will not shift. I have replaced all shift solenoids, and both trim solenoids. Borrowed a TCM from another bus no change. Compared powers and grounds from working bus. My only clue is the speedo does not work, I have switched around speed sensors. I am running out of ideas. Does the "Econ" switch have to work? Thank you in advance for any help. I am a engine person that got roped into this trans job (Charity)so I am a bit out of my area of expertise.
Rick