Yaris Gen4 iBooster Gen2

[Miata25]

Thanks for the heads up- might have to look into this and try to find one...

Edit: Found and ordered one!

[Miata25]

Unfortunately I had no luck even with the module wired in- still the same behavior- if I gently put pressure on the pedal the pedal sinks in to breaking point, if I stomp the pedal it gets hard for a splitt second, then goes soft down to the breaking point...

[Jacobsmess]

For the master cylinder itself, I'm using a Bosch 0 204 854 799 (got mine from a Vauxhall/Opel Grandland X), which has a 1" bore vs the stock MX5 (Sport) 15/16" bore and with the outlet ports on the more favourable side to mimic stock MX5 packaging.

Hi, how did you find the right MC? Unfortunately my OEM MC has an 89mm bolt spacing whereas the one uses in the ibooster I have is 100mm. I could fabricate am adapter plate and extend the pushrod but something using the right bolt spacing, bore, hydraulic ratio and brake line connections would be a lot nicer.

[itiuk]

Hi, how did you find the right MC? Unfortunately my OEM MC has an 89mm bolt spacing whereas the one uses in the ibooster I have is 100mm. I could fabricate am adapter plate and extend the pushrod but something using the right bolt spacing, bore, hydraulic ratio and brake line connections would be a lot nicer.

Honestly, it was trial and error by ordering cheap used ones off eBay and seeing which ones fit... I have a box full of old an not-suitable master cylinders I'm trying to sell back on eBay . To be honest I might have more luck using them as scrap to do some ally casting...

I do wish Bosch had a catalogue with bore, port details and such but I can't find anything.

Chris

[itiuk]

Just thought I'd give a quick update since the car has been back together and tested for a while now with the iBooster.

I have tried various iterations of CAN connectivity, and the power module, and what I have noticed is simple: the Yaris iBooster needs the LIN communication with the power module in order to work. Anything else and it either goes to sleep or doesn't power up at all. CAN seems to be for monitoring only by other systems as far as I can tell.

I'm very happy with my setup, I'm just particular enough to be annoyed by having an extra fuse box or two mounted next to the stock under-hood box. I was going to swap everything over to an MTA modular box, but mounting was a bit tight in the end - it's still on the cards for when I finally swap out the ICE for an EV setup...

[peakPWR]

I might buy a second one to tear apart if sniffing is unsuccessful.

I took one apart and the safety power supply part is kind of obvious:

[itiuk]

I took one apart and the safety power supply part is kind of obvious:

20251125_173119_1.jpg

20251125_173105_1.jpg

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20251125_173112.jpg

Wow, very nice! Thanks for doing that! Can you tell whether those ultracaps or cells?

As I learn more about these systems (dealing with them at work...) I now understand that they are primarily used as power modules to avoid voltage dropout during high draw events of the associated doohickey (i.e. when the iBooster draws high current under high load, the 12V supply in general doesn't get negatively affected).

[peakPWR]

I'd say these are supercaps. But I can't say what capacity as there are no labels and I did not desolder one to test.

[Miata25]

Just thought I'd give a quick update since the car has been back together and tested for a while now with the iBooster.

I have tried various iterations of CAN connectivity, and the power module, and what I have noticed is simple: the Yaris iBooster needs the LIN communication with the power module in order to work. Anything else and it either goes to sleep or doesn't power up at all. CAN seems to be for monitoring only by other systems as far as I can tell.

I'm very happy with my setup, I'm just particular enough to be annoyed by having an extra fuse box or two mounted next to the stock under-hood box. I was going to swap everything over to an MTA modular box, but mounting was a bit tight in the end - it's still on the cards for when I finally swap out the ICE for an EV setup...

So this might have been, why my iBooster test in the Miata with the Yaris iBooster was so strange? Pedal getting stiff an then dropping down to kind of squishy? I have the setup still here... so there might be another time or car to test it on...

Though I think I wired all the connections between the module and the iBooster...

Greets
Sven