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Discussion Starter · #1 ·
After noting on these forums very recently how trouble free out 2008 forTwo has been, the car is now showing the dreaded three bars.

It started with the gear indicator showing R when the car was in N or P (I wasn't driving, so this is a secondhand report). Then the engine died and trying to start wouldn't even turn the engine. She got the car into N and coasted to a flat spot at the bottom of the hill we live on.

I got home 30 min later and walked down to the car. It started right up and I had no issue driving it back to the house. I didn't have a full description of the problem and some of the errors sounded like what happens when the wheel speed sensors get packed with dirt (we live on a gravel road), so I washed mud and dirt off of them all. Then I tried to drive the car again.

I got one car length from my driveway when I saw the three bars and the engine died. I tried to restart it, but the engine would not spin. I did something that caused the bars to go away and the selected gear to be shown. I went through the training sequence in the many many times, but no change in behavior.

Reading that smarts don't like weak batteries and seeing that the battery was old, I replaced the battery. Now the three bars are back. The engine does not turn. I went through a bunch of different training sequences that I found on the web, but no change. Three bars. Engine does not turn when the ignition is switched to the start position.

Any ideas?
 

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I’ve had very similar (almost identical) situation happened on our 2008 smart a couple years ago...do you know if your smart’s software was updated by the dealer?(only dealer can do this and cost ~$180). If it’s already updated, it’s most likely clutch actuator(part alone ~$750). Hope this helps.
 

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So I assume your 2008 smart was not updated to the latest software from the original? If that’s the case I hope updating it will solve your issues as it did on ours...keep us updated
 

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Discussion Starter · #6 ·
So I assume your 2008 smart was not updated to the latest software from the original? If that’s the case I hope updating it will solve your issues as it did on ours...keep us updated
When was the update available? We had some issues early on that came down to a failed brake pedal switch and then subsequent failures to get the new switch(es) adjusted correctly and I think the gearbox controller software may have been updated during that exercise.

I ordered an icarsoft Mercedes/smart/Sprinter diagnostic unit and it should be here on Tues. I am expecting it will tell me that one of the gear selection motors has died. There is a body-damaged, airbag-deployed forTwo for $500 nearby and I was thinking of buying it for just those motors :)

I managed to pull the car to top of my driveway (it has a steep grade at the bottom). Once I got it up to the flat part, the car still didn't want to roll, so I think he gearbox is stuck in gear.
 

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I’m not exactly sure when the new software was available but our 2008 smart was updated about 2 years ago when we had similar problem.
 

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Discussion Starter · #9 ·
Well, jetfuel had written about how to know if your smart has had the Ver 2.0 tranny software..
..start car..put it in gear ..it will display D ...select manual mode with shifter paddle..
Yeah ... starting the car isn't an option with ours at the moment.

Amazon willing, I will have the Mercedes-specific iCarsoft code reader tomorrow and I should be able to check with that, right?
 

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Discussion Starter · #10 ·
I got the code reader this morning (USPS dropped it off at 7:30am!). After spending an hour trying to figure out how to update its firmware using a Mac, I was able to do a scan. It said that the Transmission Control Relay (N10/10k9) was not getting power. I have an electronic service manual, which includes schematics, which indicated that it gets power through fuse 30 on the SAM (the fuse block under the dash). That 40A fuse was blown. Somehow I don't think that is the end of the story, but I have to buy some 40A Littel fuses first.
 

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Discussion Starter · #11 ·
Installed a new 40A Littel fuse. The N10/10k9 code went away. Initiated transmission train-in and pop. Another 40A fuse blown. Good thing they come 5 in the pack. The iCarsoft unit is now reading codes that indicate implausible values from the M17 gear selection motor unit, so I am guessing the problem is there.

I guess I could try pulling it and checking out the brushes, but I will order a new unit as well. Anyone here know whether the brushes are a standard size?
 

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Installed a new 40A Littel fuse. The N10/10k9 code went away. Initiated transmission train-in and pop. Another 40A fuse blown. Good thing they come 5 in the pack. The iCarsoft unit is now reading codes that indicate implausible values from the M17 gear selection motor unit, so I am guessing the problem is there.

I guess I could try pulling it and checking out the brushes, but I will order a new unit as well. Anyone here know whether the brushes are a standard size?
I don't recall the size offhand, but I think it's in my teardown thread. Looks like the old ones will need desoldered and the new resoldered, but it doesn't look too bad.

Edit: Shift motor teardown (and maybe someday, rebuild)
It is not in there, but I found the info...the brushes seem to be 6mmx7mm and could be approx 15mm long.
 

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Discussion Starter · #13 ·
Thanks for the info.

For anyone looking at this thread in the future, for reference on when this happened in the life of the car, we took delivery of our car in Sept. 2008 and it has about 109k miles on it now.

Got a new motor (technically pair of motors) ordered and it should be here on Thr. Got the old one out just now. I am sure some day my hands will heal.
 

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Discussion Starter · #14 ·
The new motor arrived today and I installed it. The car will now start, but all is not well.

I had to go through 3-4 teach-in cycles before I would get "P" and not three bars when I switched the ignition on. I can put the car in "D" and drive it forward. However, it can't find reverse. Selecting "R" results in a blank (no gear) being displayed. Since I haven't reinstalled the airbox, I haven't tried driving the car more than a few feet.
 

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Any other codes besides the P0886, assuming you are still getting it?
If it's blowing fuses, there's something electrical wrong is my thought. Have you checked the harness? It's not a trivial process to check it, but having just recently removed part of it to take out the drive train it's not a terrible process. You might have a spot where the wires have rubbed against something else and created a short?
A seized/bound motor or a short are the first things that come to my mind.
I suppose it's possible the TCU itself has failed, but I would think that would generate a lot more codes.
 

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Discussion Starter · #16 ·
Since replacing the gear selection motor, it hasn't blown any fuses. After the last train-in, the TCU wasn't throwing any codes.
 

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Discussion Starter · #17 ·
The train-in isn't sticking. I am getting codes for implausible signals from M17 (the gear selection motor).

I will initiate the train-in, but need to wait for the gear selection motor to do something before the car will start. "N" and "D" flash when I select them, but they appear to do their thing. Selecting R displays nothing and no gear is selected.
 

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Discussion Starter · #20 ·
I pulled the gear selection motors and checked things out and didn't see any problem.

Should it be possible to turn the gear selection drums by hand?

The 1/3/5 drum in my car does turn by hand, but the 2/4/R one doesn't. Given that the initial problem started with R and now the car won't select reverse, I wonder if the problem is some mechanical issue with that drum.
 
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