T/M shifter

My 2006 Malibu LS 2.2 L has a big black button on the top left side of the shifter. It has a “+” & “-” sign but the manual doesn’t even show or explain what it’s for. Can anyone let me know the purpose of this button? Thanks.

I would say it is either to turn the overdrive off, or your car has an ‘autostick’ feature, which allows you to manually shift your automatic.

I first thought it was for overdrive. But I read the manual again last night, page to page not just the section on T/M. I finally found it. Shift to LOW ( L), you are actually in L3. Press the - sign each time to shift to L2 & L1. Press the + sign each time shift back to L2, L3 & L4. Shift to DRIVE (D) to get out of this automatic select mode. I have been driving since 14 & this is something new & different compare to my other cars or to all the cars I had driven. Then where is the overdrive?

What you have is 4 speed auto with manual shift (+/-) option. No overdrive. Or you can look at L4 as your overdrive, if you like.

Starting out from a stop with the shift selector in the “L” position, you can hold the transmission in any gear, controlled with the button on the left side of the gear selector lever, but it will not go into lockup or overdrive as you call it. The gear selected is indicated on the dash readout near the speedometer. For lockup you must move the selector to the “D” position.

The “L” selector can be used to keep the transmission from hunting in and out of lockup in a hilly area or when towing a trailer. Holding the transmission in a lower gear has otherwise very limited usefulness in my view.

Correct me if I’m wrong. Isn’t shifting to LOW (L) usually done for going up or going down hill, or pulling trailer, with speed of up to only 35-40 MPH, & not for freeway driving (60-70 MPH)?