2004 Malibu Maxx electronic gear shift problem

2004 Malibu MAXX electronic shifter not functioning on the manual mode. When the shift is on overdrive, it works fine by itself. But when I try to lock into low gear and use the +/- button to shift between 1-3 is not working. Once the stick is in L, it constantly displaying L3 and cannot manually down shift. Just wondering anyone might know what is wrong.
Thanks

Doubtful that the switch is bad. I fixed mine after I noticed it was doing funny things such as downshifting after letting of the gas and then back on even lightly the tach would jump about 500 rpm and you could feel a downshift for a second. This was happening at city speeds. Then I noticed the manual shift didnt work either, as you described.

I took the console off and the problem stares you right in the face, a broken wire. There is a pink and a yellow wire going across the bottom and drivers side of the shifter that go up the shifter shaft to the switch. There was no hunting for an internal break in the wire, the yellow wire was completely broken, insulation and all, just like it had been cut. I cut the pink wire too and spliced in an additional 2 inches on each by soldering and wrapping them. Put it all back together and everything now works as normal. No weird shifting problems and the +/- button works again. All in all it took about an hour and was quite easy.

Not sure why a shop would go to the extra work of replacing the switch. Maybe because it comes with the wiring harness which is really where the problem is. Mine was quite visible but others may break inside the wrapped part of that harness. I think this will be a common problem since GM strung that wiring harness too tight and used fairly light duty wire.