Can unplugging the TCM resets the check engine light on a 2009 Chevrolet Cobalt LT 2.2L?

Question

2009 Chevrolet Cobalt LT 2.2L Automatic. I unplugged the connection to the TCM, and the check engine light went off. Was the bad connection the problem?

Answer 1

P0751 1-2 shift solenoid valve performance - No first or fourth gear

This code is a type "B" code what type B does is  if the problem exist on the first drive cycle the ECM stores it, On the second drive cycle if the problem still exist it is recorded and stored along with a freeze frame and the CK ENG LT comes on. Disconnecting the TCM would be the same as clearing the code. If the code is cleared and the CK ENG LT for a P0751 does not set you may of had other condition that exist that would set a P0751. Transmission fluid, contamination by definition of worn transmission fluid. (transmission fluid does wear out due to mileage and use) . what happens is at the transmission filter there is a filter seal. if that seal does not correctly seal  you can set a P0751.   There is also  TCM that  could of set a P0751 if it is not capable of supplying  correct voltage ignition  to the solenoid. By the way just disconnecting the TCM it reset the TAP (transmission adaptive value) it will then go to a relearn cycle.

Answer 2

P0751 CHEVROLET Code - 1-2 Shift Solenoid Stuck Off

Read more: https://www.autocodes.com/p0751_chevrolet.html