Wife's car illuminated the CEL. Checked codes and got a P0750. Engine runs fine, the transmission doesn't. No normal up shifting in D, goes straight to 3rd. No OD or lock up. Manual 1st works, manual 2nd does not. Any insight here?

 

Check this link for code P0750.
https://www.engine-codes.com/p0750_chrysler.html
I'd start with the transmission fluid. Is it low? How many miles? Has the fluid and filter ever been changed? I'd probably start there. After that, you are looking at solenoid or harness which would be more of a job to track down.

 

It was low when I checked it. Adding didn't help. Heading out today for a filter and flush to see if that helps. 125K miles, hasn't been changed to my knowledge. If things don't improve, I know a very good transmission guy.

 

Flush and filters didn't help. My transmission guy now only does high performance diesel transmission. I can't blame him, big money up here in AK. Any recommendations on an off the shelf exchange?

 

Well, been sitting in a transmission shop for a month now untouched. They keep saying we will get to it tomorrow, now they won't answer the phone. I guess I need to go down there and make them nervous.

 

Wow. Sitting for a month. I'd be on them too.