I have a 2009 pontiac g8 gt, when I try to switch to manual it goes to m1 but won't shift up. My drive and sport mode work fine but say I'm in s5 and shift it to manual, it goes to m5 but still won't shift up but will shift down, what could it be?
it could possibly be a fuse because I believe those shifters run off of computer systems id start by checking the fuses and the wires to see if any are damaged or blown
In situation like yours you will need a scanner to see what the ECM commands via the switches as well as any codes that may be present. When you shift any of the up/dn switches the ECM will either see it or not. if it see it then it commands the trans to shift. if the traans doesn't shift then the problem lay in the trans. if the ECm does not detect the switch even if your holding it..then the switch is suspect of not working. So it really comes down to is the problem electronic in the switch or a solenoid in the trans or inside the trans itself. The scanner will at least tell you what the ECM has found or not found as a problem.
