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Toyota Aygo Semi Automatic MMT P0900 Clutch Actuator Circuit

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Hey Guys, I need some help. I have a 2007 model Aygo which is showing a P0900 Clutch Actuator Circuit code. After extensive Googling I gathered that I will need to get my Actuator rebuilt, issue is probably to do with motor brushes being worn out.


Question 1: I am looking to install Techstream on an old laptop, I would like to know which version of Techstream will allow me to perform the pre-requisite Clutch Clamp Position Adjustment before I can remove the actuator from the car. I will then need to perform the Initialisation of the MMT ECU, Initialisation of the clutch and finally the MMT system learning/reprogramming. I read that the latest versions of Techstream have has some special features removed and require net access.


Question 2: Can someone recommend a mini VCI cable and what version of it? I need a cable that not only reads and clears codes but also allows for the MMT initialisation, etc. A cable someone has personally tested and can recommend. Too many on the net but the reviews not so great for most.

PS: Is there anyone in West Yorkshire (UK) area that can help? If so please DM me.


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  • 2 weeks later...

Hi, Flash22,

when you say no need to clamp the clutch i think you are saying that if your just taking the actuator off for repair and striping it down would alter it first setting position anyway and so long as you place the parts back to where you first checked them, all is needed then is to reprogram it manually if you dont have any other means. But what about if you want to replace the whole clutch assembly? and is correct that there is a difference between the manual and auto clutch as it sometimes mentions when checking Manual or auto or sequential with the auto being more expensive? thanks. 

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The clutches as ever so slightly different, you can clamp it or not, it just zero positions the actuators - you need to do it when changing the clutch that's for sure

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Thanks Flash22. 

Haven't found any local mechanics keen to take on the job. Some have even advised to scrap it - didn't realize the issue was that big but it appears the initialisation process can be hit and miss and may consume a lot of time before there's a result for this reason the garages aren't very keen to work on a Semi automatic.

For anyone refering to this post in the future I will update if I manage to get it fixed. There are some great videos on YouTube by Vak_Service (search Vak_Service in YouTube), he's done a great job in explaining and showing how to repair the actuator.

I also gathered that Autel MK808 and above models have the hot function to Initialize the Clutch, I knew Launch did and so does Tech Stream - maybe this will help someone.




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Yes, It's either Techstream or higher end scan tools, that's why the main dealer does a CYA by replacing everything

yes, they can be a Pita, you have to do the manual initialization to the letter

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  • 4 weeks later...

Thanks Flash22 for sharing the useful material.

Through lots of help from the online community and a great guy on YouTube 'Vak_Service' I have been able to fix the issue with my Aygo MK1 actuator. The diagnostic tool showed a P0900 Clutch Actuator Circuit Code. To fix this I got a friend to remove the Actuator for me, I did not perform any steps using a diagnostic tool or manual steps before removing this part. Once the actuator was out I disassembled the servo motor, it was covered in black dust from the carbon brushes, see pics. My friend and I removed all loose dust and then cleaned the unit. We then reassembled it and connected it back to the Actuator. We also ensured the shaft from the Actuator was not fully extended before fitting it back. Once fitted the car ignition was turned on and within a few seconds the snowflake/cog looking light went off. The car was then started and taken for a test drive and everything worked fine. A slight loss of power/***** when it changed from 2nd to 3rd which I am currently investigating, could mean that it needs reprogramming.

Just to summarize, to fix the P0900 issue, no diagnostic tools were used to perform a pre and post action before the actuator was removed  and after it was fitted. I also did not replace any parts, a simple cleanup of the black dust. As the brushes looked good I did not replace them. I did not open the actuator as the code indicated a circuit issue which was due to server motor. The light on dashboard went off itself. The job took around 45 mins to an hour.

Some pics attached for future reference, if anyone has a similar issue.

Tip: Make a video or take pics as you disassemble the unit as we could not figure out where one of the parts went until I watched YouTube videos.

I also recommend you watch videos from Vak_Service, he explaines the MMT issues well.IMG_20220808_160331.thumb.jpg.a7c26f017e2355bbbf7c1ae0d401b4b0.jpg





Some discussion on diagnostic tools covered in this post:


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