1-2 solenoid
 

1-2 shift solenoid issues.

Okay, I've done the fluid change, pulled the codes and drove it while on my snap on scanner.

Computer is showing the 1-2 solenoid changing to on/off but it is not actually changing gears.

Code agrees, 1-2 solenoid. So.....I am wanting to confirm it's not a simple connection or ground.

what next? Would like to check resistance on the solenoid but unsure which wires into the TCM to check.

Eyes and fingers are cheap tools.

not sure your point but I have read and searched before posting. Do you have a helpful comment?

The solenoid is inside the transmission, but you can inspect the harness at the front of the transmission case. I believe it’s a possibility the solenoid has failed.

The helpful suggestion is to use your fingers and eyes to see if any of the wires leading to the transmission are compromised. That is what to do if you are concerned about bad wires.
Sorry if that sounds offensive but you asked "what next?". After that I would start by checking continuity of all of the wires leading to the transmission, then check the resistance of the solenoid (if you know what it is supposed to be).

Not offended by helpful direction at all.

From what I've found, the reading should be between 19 and 31 ohms. I can easily check them at the tcm if I knew which wires they are.

I will check continuity between tcm and the transmission harness next.

I've tried to disconnect the main harness from the transmission harness with no luck. How do I remove that plug in?

In here there are photos and advise

https://www.chevyhhr.net/forums/driv...d-61313/page3/

Been through that thread several times but never thought of getting the wire colors from that pic. Thanks. Now I just need to figure out how to disconnect that harness.

Chances are slim that the problem is electrical. I wouldn't waste a lot of time on it.

There’s information in here

https://at-manuals.com/manuals/4t40e-4t45e/