I found a tech bulletin. Codes are not always set when a part fails or other issues appears, I know from experience.
This bulletin is being revised to add the 2004 model year as well as the Chevrolet Classic model. Please discard Corporate Bulletin Number 02-07-30-022A (Section 07-Transmission/Transaxle).
Some customers may comment that the Service Engine Soon (SES) indicator is illuminated and that while the light is illuminated, transmission shifts are extremely harsh.
These types of conditions may be caused by an intermittent connection at the transaxle 20-way connector to the wiring harness interface.
If a DTC was recorded and the Freeze Frame and Failure Records back it up, a problem existed at one time with the wiring and/or the connectors between the transaxle and the PCM. Therefore, a thorough inspection and/or repair of the wiring harness at the transaxle 20-way connector for one or more of the following conditions may be warranted.
• The wiring harness is stretched too tightly or other components are pressing on the connector body itself causing a downward pressure on the connector body and possible intermittent contact of the wiring terminals. Ensure proper clearance to any other components and wiring (i.e. hoses, battery cables, etc.).
• The terminals are not fully seated into the cavity of the connector body.
• The male terminals in the transaxle portion of the connector may be in the wrong position (i.e. bent).
• The female terminals may be loose and are not making proper contact. Check the tension with the proper terminal tester from the GM Terminal Test Kit J 35616-A or J 35616-92. If the tension is low, replace the terminal. Do not try to re-form the terminal.
• The crimp of the terminal to the wire may not be satisfactory (i.e. loose, over insulation, etc.).
• The wiring connector is not properly seated and locked in position. Ensure proper seating of the connector into the transaxle and that the connector is properly locked in place.
I had the code for the wiring but can not get it to paste in correctly. Maybe I will take a screenshot if it is needed.