Long story short, my 2008 Smart Fortwo I had recently purchased would occasionally throw 3 bars, usually shortly after starting it and typically when shifting into drive, but not always. Sometimes it would throw 3 bars from the start, sometimes it would go a few days, even a few weeks one time, without any issues at all. When it would throw the 3 bars I could re-train it a few times and it would sometimes be fine all day, sometimes it'd throw 3 bars a mile down the road then one more retrain and it'd be fine for the rest of the drive. Frustrating would be an understatement.
Codes I got (these did not show up for a basic ODBII scan, need something that talks canbus)
Module "N15/6" (Sprintshift Control Module)
P0707 - Signals from incremental sensor of component M17 (gear motor) are unreasonable
P1800 - Transmission teach-in was required
P1801 - Teach-in of mechanism not successful
Module "N47-5" ESP control
C1301 - short or open circuit of CAN wires
I did all the usual things, looked for shorts (especially considering the C1301 error) and found nothing. I was pretty sure the issue was with the shiftmotors, so I started figuring out how to get to it. I note here that I posted this at clubsmartcar.com at the time and am reposting much of that here to be of use for members here. There was input and suggestions from others, there and elsewhere to help as I went, community payback is part of the motivation for posting here.
The TL;DR here is I replaced the shift motors, for everyone else....
It seemed easiest to get to the shift motors from up top, but the airbox is is in the way. It was not terribly intuitive where the bolts were, I marked them here with red arrows. The one on the right I did not remove and instead channeled the powers of my alter-ego, DumbStrong, and broke the plastic mount. Whomever approved putting that bolt in like that earned my ire; due to the angle it seems to me the only way to get to it is to drop the subframe. Breaking the mount didn't harm much, so whatever.
Once the airbox was out of hte way, I felt I had a chance of actually getting this done. Here's a shot with the airbox out of the way.
At the top of the shift motors, you can see some dark stains; I believe this is from fluid/vapor coming out of the vent and settling there. The top two bolts might look crusty, but they were shiny new compared to the bottom two.
It took me a while to figure out how to remove the plugs, eventually I got some images which showed the tab on the front and with a bit of jggery pokery figured it out. I slipped a small screwdriver in from the face of the plug, below the tab in the center and gently lifted the tab up and it came apart easy. The arrow in the pic with the plug shows where I inserted the screwdriver.
And a shot of the crappy bottom bolts. You might not think it, but some penetrating oil, a day to soak, and the torx cleaned out well enough to remove them.
Codes I got (these did not show up for a basic ODBII scan, need something that talks canbus)
Module "N15/6" (Sprintshift Control Module)
P0707 - Signals from incremental sensor of component M17 (gear motor) are unreasonable
P1800 - Transmission teach-in was required
P1801 - Teach-in of mechanism not successful
Module "N47-5" ESP control
C1301 - short or open circuit of CAN wires
I did all the usual things, looked for shorts (especially considering the C1301 error) and found nothing. I was pretty sure the issue was with the shiftmotors, so I started figuring out how to get to it. I note here that I posted this at clubsmartcar.com at the time and am reposting much of that here to be of use for members here. There was input and suggestions from others, there and elsewhere to help as I went, community payback is part of the motivation for posting here.
The TL;DR here is I replaced the shift motors, for everyone else....
It seemed easiest to get to the shift motors from up top, but the airbox is is in the way. It was not terribly intuitive where the bolts were, I marked them here with red arrows. The one on the right I did not remove and instead channeled the powers of my alter-ego, DumbStrong, and broke the plastic mount. Whomever approved putting that bolt in like that earned my ire; due to the angle it seems to me the only way to get to it is to drop the subframe. Breaking the mount didn't harm much, so whatever.
Once the airbox was out of hte way, I felt I had a chance of actually getting this done. Here's a shot with the airbox out of the way.
At the top of the shift motors, you can see some dark stains; I believe this is from fluid/vapor coming out of the vent and settling there. The top two bolts might look crusty, but they were shiny new compared to the bottom two.
It took me a while to figure out how to remove the plugs, eventually I got some images which showed the tab on the front and with a bit of jggery pokery figured it out. I slipped a small screwdriver in from the face of the plug, below the tab in the center and gently lifted the tab up and it came apart easy. The arrow in the pic with the plug shows where I inserted the screwdriver.
And a shot of the crappy bottom bolts. You might not think it, but some penetrating oil, a day to soak, and the torx cleaned out well enough to remove them.