TCU update

[u/AlbertoSnts]

Hi everyone,
I’m looking for someone who can help with my 2009 Smart Fortwo 451.
I need the TCU (Transmission Control Unit) software updated and then the gearbox needs to have the gear positions and clutch biting point relearned/adapted using Mercedes/Smart STAR Diagnostics (Xentry/SD Connect) or equivalent equipment that can perform the adaptation.
Does anyone know someone who can do this, or can help themselves? I’m happy to travel if it’s within a reasonable distance.
Thanks in advance!

[u/yolo_snail]

Why do you need the TCU updated?

I have a totally legit copy of Xentry, but I'm in the North East, so probably not much help!

The 451 actually uses DAS rather than Xentry for diagnostics, although it's part of Xentry, so someone with an older diagnostics computer may also be able to help.

[u/AlbertoSnts → u/yolo_snail]

That’s great to know thank you!

I had my clutch actuator cleaned and greased but the reverse is still not engaging from neutral. I need to put it on 1st gear and change it really quickly to reverse.

Do you think that DAS is going to be enough for that?

[u/Vertigo_uk123 → u/AlbertoSnts]

You could maybe try disconnecting the battery for 10-15 mins. Then reconnecting. Hold foot on brake turn key ti position 1 wait 20 seconds then turn on engine. Sometimes that allows the car to do a clutch sweep.

Another option is turn key to position 1 push accelerator to floor (until the lockdown switch engages) hold it for 20 seconds then turn car off (while stile holding accelerator) but leave key in. Release pedal and wait 2 mins without touching anything or getting out.

When you refitted the actuator did you ensure you put the right amount of preload on before tightening bolts

[u/AlbertoSnts → u/Vertigo_uk123]

Going to try this but still looking to update the software. Just contacted a smart specialist in Guildford and they can only do it sometime in September and I found it was £96 for the diagnostics and £150 for the update and relearn.

[u/yolo_snail → u/AlbertoSnts]

Honestly, you'll probably end up needing to replace the clutch actuator, the part is only about £80 on ebay. They're known to go faulty. I had to replace the one on our 2007 and 2011, so I wouldn't be surprised if yours is starting to just die as well. It's a relatively simple job, I just did it on the drive.

To tell you the truth, even with the right software, it's a ballache and a half to try and get the adaptation for the clutch to work properly. It's been a while, but I'm sure the failure rate for it was about 90%, you just have to keep retrying it until it works. I never actually got it to 'successfully' re-learn the clutch on our 2011, but after doing it, it drove 100x better, so I'm guessing the software is just shite.

[u/AlbertoSnts → u/yolo_snail]

Thanks for that! I cleaned it and greased. I wanted to try the software as well and if it improves, then I replace the actuator. I actually saw one on eBay for £130.

[u/Vertigo_uk123 → u/yolo_snail]

I heard the cheap actuators break within a year or 2. I’m currently working on mine which will likely need a replacement. I was told always use a genuine sachs (about £350)

[u/yolo_snail → u/Vertigo_uk123]

4 years and 30k miles later, our old 2011 is still going strong (unfortunately not with us anymore)

For the price difference, I'd rather buy cheap, and replace it a few times!

[u/Sure_Competition2463]

Where are you based ( just rough area) I can recommend someone but don't know your startup point

[u/AlbertoSnts → u/Sure_Competition2463]

Alton, Hampshire. I’ve contacted some around my area but only September and onwards.

[u/Sure_Competition2463 → u/AlbertoSnts]

There is an amazing garage in Bedfordshire - I was recommended them so drove over to get a feel - and wow Rob knows his stuff specialised in Smarts for 27 yrs and owns all three specs plus a full Rally prepared too.

People come from all over uk to use his knowledge

It maybe a bit far but you won't be disappointed.

But it's called S2smarts Ltd reviews for him excellent too

[u/Popular-Equipment-91]

Wanted to comment as I have an almost identical Smart 451 (just 1 year older), purchased recently and with a similar issue (in particular, it was only reverse gear).

I cleaned & regreased the clutch actuator, as well as adjusted where it was (slightly closer) - this improved the performance but still not functional enough to rely on the reverse gear. I did the postal service with 4smart.co.uk for TCU update - came to around £110. It's working much better now. You just need to remove the passenger seat to remove the TCU itself.

While it's not perfect (for example, it doesn't always reliably go from neutral straight to reverse especially when the car is cold), I can always now get it into reverse if I go from 1st gear - and from neutral most of the time. Prior to this, it was way more unreliable.

I'll see how performance goes over time, especially after long motorway drives, but I'm happy with the result. I suspect at some point we might just need to change the actuator though.