2007 G35 sedan. I've been driving the G exclusively in manual mode for the last year or so (can't stand the slowness of the "D" mode) and loving it. Just recently, unless I'm tripping, it's starting to take more effort to down-shift. I actually have to make sure the shifter hits the wall on the downshift (a click alone won't do). The upshifts appear to be fine. I've researched some threads but haven't found anything conclusive. I might tear into it today to see what the mechanism looks like and if anything looks out of place.

People mentioned some switch underneath the console or even the whole assembly itself. I'm okay with replacing whatever it is, but wanted to see if anyone had dealt with this issue before and what was the resolution?

Thanks.

 

If the problem was in the limit switches then it simply wouldn't work AT ALL.

I'm leaning more towards the transmission hasn't been getting flushed every 30k miles as per the maintenance schedule and the friction coefficient of the fluid is poor now.

If it STARTS the shift at the correct time when you hit the shifter but it feels like it shifts sluggish then that's probably a friction modifier issue. Drain/fill the tranny fluid on two consecutive oil changes to get the old fluid out and fresh fluid in to see if it makes a difference. AT fluid is only good for less than 100k miles before it starts to behave very poorly.

 

But if it's actually NOT SHIFTING when you move the shifter then that's probably an issue with those microswitches inside the console on the shifter assembly itself. Might be something that can be cleaned with some electrical contact cleaner, just make sure you use one that's safe for use on plastic.

 

the issue is definitely not mechanical, the trans shifts beautifully. i took the shifter console off, and the manual mode is operated by two small metal arms pressing against up/down switches via the shifter. nothing appeared to be off, so i blew some dust out and put it back together. worst-case, i'll have to replace the assembly/switches, so i'll update if it does end up dying on me.

 

Definitely sounds more likely to be the switches. I have no idea what is in there but I have to presume there's a microswitch for "up" shifts and a different one for "down" shifts. I used to deal with industrial-grade microswitches (want to say Omron brand) and they used a thin, metal strip, some with a longer strip with a bent end where contact was made. You could actually bend them back a bit in order to make contact better. Could be something that simple.

 

i was thinking about "bending" that small metal arm, but it's not exactly fixed in place, there is some pivoting to it. here's what it looks like:

 

That's exactly what I was thinking they might look like. If you press the arms gently against the switch (plunger) itself, do you hear it click ? It might not unless it's powered though. If it does appear to click normally and consistently, I wouldn't hesitate to bend the arms in order to apply more pressure to the switch. Just don't bend it too far that the gear shifter doesn't reach it well enough.

Is there just that single screw holding each switch in ? If so, if that screw isn't tight, the switches may pivot, moving closer or away from the mechanism that engages the switches. Or is that what you mean by "there is some pivoting" ? I would think there shouldn't be. Maybe the two outside protrusions lock it in position ?

 

yeah, it clicks, but the gear doesn't change with just a click - you have to keep pushing it in some more.

re: pivoting. if you look at the top left/right of each respective screw, the arms attach to a pivoting point. they are not rigidly attached at the bottom, so that's why i was hesitant on trying to bend them without the risk of breaking them off.

 

I'd suspect the microswitches are faulty or failing.

 

Spray electrical contact cleaner into the plunger part of the switch itself. The contact is dirty if you can hear the switch click but there's no continuity through it unless you press harder.

Or replace it.

 

just to update. the manu mode switch ended up failing a few months back, so i swapped the new assembly in. pretty easy job, tho the unit i got was for the coupe and the metal arm that connects to the tranny was shaped differently, so had to swap the guts over to the old one. easy repair other than sweating over trying not to break the plastic trim crap.