Hey guys, I converted to a 4L80e behind my LSA. New converter from CirleD and can’t get the converter to lockup. Tuner said the trans temp is flipping back and forth from actually to -40 not allowing the converter to lock. He can manually lock it on dyno but won’t lockup on its own. Sound like temp sensor issue? Or TCM issue?

 

Sounds like a bad connection, wiring issue. -40 is like open circuit. The harness had to be repinned or added if u were manual. I would suspect a wiring issue before the sensor our trans internal harness.