One minute my truck is fine, the next the transmission isnt shifting right. If i give it gas it acts if its in nuetral. Manual mode is the same. The codes it is throwing goes ad follows
U0100 (×2) U0109 P0606
My car has 135000 miles.
My car has an automatic transmission.
Those are pretty serious codes referring to communications failures between control modules as well as potential failure of the PCM itself. Most electrical failures are wiring related (corrosion, bad grounds, wire break, etc.) and diagnosing this will proceed with those presumptions in mind. Once every possible wiring or interconnection fault is ruled out, at that point you think about reflashing the PCM and/or other controllers referred to in the codes. If that doesn’t work, you sub out for a known good PCM. The problem is traceable but you are looking at pages of steps to go through and you will have to have, in hand, a copy of the Factory Service Manual plus any applicable Technical Service Bulletins published by GM on this issue. There is no other way to do the diagnostic because the schematic you go through is a huge decision tree. If you want these steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a check engine light diagnostic - CAN bus failure and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.