Hello, my girlfriend's 1996 Cutlass Ciera Wagon with the 3.1L V6 doesn't seem to want to shift out of third gear while driving. No matter what speed you're going it doesn't want to downshift or upshift from third. Even starting from a complete stop, you nearly have to floor it to get the car moving. It doesn't shift into overdrive either if you drive at highway speeds. The service engine soon light is on and the following error codes were pulled:

P0753 - 1-2 Shift Solenoid Circuit
P0758 - 2-3 Shift Solenoid Circuit
P1406 - EGR Valve Pintle Position Circuit
P1651 - Electric Cooling Fan Relay Control Circuit
P1652 - Electric Cooling Fan Relay Control Circuit
P1655 - EVAP Purge Solenoid Control Circuit
P1864 - Torque Converter Clutch Circuit

There doesn't seem to be any other symptoms that I know of. The car starts and runs fine. I do know that the car will shift into first and second gear if you manual do it using the gear selector. I was wondering if anyone could tell me what to look for or maybe how to fix it. Any help would be greatly appreciated. Thanks guys!

 

Just a quick guess based on your codes, you may have something as simple as a wiring or connector problem. I would check the connectors on all wiring going to the trans for kinks, breaks, bare spots, etc. Also unplug and examine the connectors for corrosion, bent pins, water and obvious problems.
Some of those may be old codes, so I would first have them all cleared, and see which ones come back.

 

I suspected the same thing with the source of the error codes being the wiring harness or something like that. I did clear the codes and after driving around for several minutes, the codes returned. I did a visual inspection of most of the wiring under the hood and didn't see any obvious damage or corrosion. The wiring harness leading to several components has a plastic shield thing covering them making it a little difficult to inspect.