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Discussion Starter · #1 ·
please help my Smart Fortwo show three bars on dash and I’m try to replace TCU TCM transmission and tran clutch slave actuator still show three bars , please anyone help me
 

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Discussion Starter · #3 ·
If you get three bars on your instrument cluster, try this to retract the transmission:

  • Step on the brake
  • Turn the key to the “on” position, but don’t start the car.
  • Slowly cycle through the gears, pausing at each position. You should hear the shift motor and clutch actuator moving.
  • Slowly cycle back through the gears to Park.
  • Take your foot off the brake
  • Turn the key off
  • I’ve heard that locking and unlocking the doors at this step is necessary, but I’m not convinced. You can try it anyway.
  • Wait a few moments.
  • Restart the car. The clutch should function again.
thank you for reply & help me
But I’m did already but didn’t heard anything shifts motor and clutch moving,

😥😢
 

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Discussion Starter · #11 ·
The U0103 indicates the TCU had a problem receiving data from the shift selector. There are electronics in the shift selector that are also powered through the TCU. If the TCU isn’t getting power, neither will the shift selector module.

The P0877 is a sprintshift module fault. The first thing to check is the battery. You should definitely have it load tested. Just a voltmeter measurement isn’t good enough. Most auto parts will test batteries for free. Smarts are prone to odd errors if the battery is low, even while while the car is running.

After testing the battery, Xentry indicates that the automated transmission relay (N10/10K9) might not be working. It’s part of the SAM and is powered by a 40 amp fuse in slot 30 and also powers the sprintshift module (TCU). If the SAM is supplying power to the relay, you should be able to hear the relay click on and off as you toggle the key on and off. If there’s no sound from the relay, check the fuse. If there is power and the relay is clicking, move on to check the TCU.

The TCU is under the driver’s seat. You might need to take the seat out to get to it. If you don’t have the subwoofer, you might be able to get to it without removing the seat by moving the seat forward as far as it will go. There is a split in the carpet you can peel back to have a look. If you have the subwoofer or can’t see it well, the seat should come out, but…. DO NOT TURN THE KEY ON WITH THE SEAT REMOVED IF THE SEAT AIRBAG WIRING HAS BEEN DISCONNECTED! If you do, you will need to find some with Xentry or a high-end scan tool to reset the airbag system.

Power to the TCU fed from the Automatic Transmission Relay is on red/blue wires in connector positions 1 and 3. The grounds are on brown wires in positions 2 and 4. You should be able to see the supply voltage from the transmission relay when toggling the key in and off if the relay, fuse, and wiring are ok.

So…

If there is no power to the TCU and the fuse is ok, it could be that the relay or SAM are faulty.

If there is power from the SAM, but not at the TCU connector, there’s a wiring problem.

If there is supply power to the TCU, but you are still having issues, it could be the TCU is faulty. A careful look at the connectors would be the next place I would look. Since it’s under the seat, it can get wet or corroded. It’s worth having a close look.

Let me know what you find!
Hi 👋 thank full for help.
I am have two Smart Fortwo and one from US and from Europe, I’m try already remove TCU under seat of Europe smart and plug to US smart car and press break a few minute I hear sound of Motor gear after that on dashboard show N but shifter can’t move to P R N just only show N and I can start car ( engine running), for a Fuse I check ready is okay.

I really don’t know what going on 😢

thank everyone help me please continue to help me more 😢
 

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Discussion Starter · #16 ·
Matthew,

Did you follow the steps in post #8? If yes, what were the results?

Swapping TCUs from one car to the other will require the reprogramming so the SAM and TCU’s VIN numbers match. This is typically done using a Mercedes Star Diagnostic system or a high-end scan tool.

If you are able to see something on the gear shift display
and have parts. Maybe the next step should be replacing the shift actuator.

Before swapping parts, I would suggest following the steps in post #8 and moving on from the results of what you find.
Ok i will follow the step in post 🙏

thank you 🙏
 

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One other thing I experienced with the 3 bar, is the time I deep cleaned my smart and completely removed the gas pedal, it's a totally digital system that bolts to the floor and just unplugs. The gas pedal is just a electronic contraption that is bolted to the floor nothing from it actually penetrates through the floor or bulkhead like on normal cars. Like a pedal on a showing machine. Well I guess I didn't plug it back in enough or something and when I re assembled it -I got the 3 bars. Knowing it's the only thing I removed. I removed it again and checked the plug and sure enough it had not clicked into the pedal enough. Did you accidentally Kick it extra hard? You might want to check it.
 
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