SMART FORTWO - GEARBOX ISSUES

[Brent74]

Bought a Smart ForTwo Petrol auto (64 plate) two weeks ago; it’s just broken. Gearbox failure. Recovered to the garage where I bought it and they’re saying that the battery compartment is full of water and that I need a new ECU, which I take to mean - clutch actuator? I had informed them the week before that the hill assist wasn’t working at all, which I assume is also controlled by the actuator. No clue where the water has come from though? Any thoughts?

[Mjolinor]

They are very prone to leaking round the windscreen and the back plastic windows. ECU will be referring to the SAM, not the actuator as the water drips directly onto it from the windscreen.

Unless they are a Smart specialist then I would completely ignore what they have told you and take advice of the way forward from here.

 

If you search for "fq101" and  "Evilution" then you will find articles  on there about windscreen leaks, how to find them and how to fix them.

 

[Willys]

The SAM is basically the fuse box and computer combined, there is also an ECU on the side of the air box to the left of the engine then there is the speedo all 3 of these magic boxes must be able to speak to each other to get the car running. 
As for the windshield leaking, is the car a hard top, sun roof, glass roof or a convertable soft top?  Look at the rubber seal which isn't really the seal for the glass it is decoration so to speak and look for rusting at the corners of the glass and also at the middle at the bottom of the windshield. Get your fingers under the glass and see if it moves at all? I could get a flatblade screwdriver under the middle of mine and lift it 1/2"  ffs...!  As said above the back side plastic windows leak all the time unless you silicon them down. The track for the sunroof will also leak. The only roof I have had that didn't leak is my glass roof. But that was the car that the windshield was so loose I could lift it 1/2" in the centre of it....!
As for the water in the battery well drill a hole in it and allow the water to escape.....better than mopping it up daily! 
The actuator you speak of is the mechanical clutch mechanism.....that must be adjusted from time to time and re-taught in the worst case. 
As suggested go to those two site for advice, donate the smallest donation at Evilution to get all the information available, well worth it IMHO. especially when you first own a Smart Car.  We here seem to concentrate on the CDI 2005-2006 version but have information about all smart cars.  What year is a 64 plate car? That will help greatly in Canada as we don't license them the same here. We strictly go my date of manufacture. etc.
Check the SAM for burnt or corroded connections on the top of it, then take it down and carefully disassemble it and look for bad solder joints called cold solder joints. You will see a very faint ring around the pin in the solder where the pin has heated up and cooled which has broken the connection for that pin on the circuit board. It can easily be fixed by taking the old solder off and re-soldering the pin using new solder.  All this explained with pictures over at Evilution. if I remember correctly.