Yaris Gen4 iBooster Gen2
Yaris Gen4 iBooster Gen2
I'm starting this thread to share some information I've found specifically regarding the Gen2 iBooster found in the Gen4 Yaris, and the possibility of using this in homebrew applications.
For my own project, I'm taking the long approach to one day electrifying a 2003 Mazda MX5 (NB2.5). It's not my daily driver but I do want it off the road for as little time as possible. I'm therefore tackling as many small jobs as possible ahead of the conversion. One such job is deciding what to do about the factory vacuum brake booster. I don't like the idea of standalone vacuum pumps, and I'm not keen on de-assisting the brakes either, so the electric booster option is an option I want to explore.
Firstly, I did try a Gen1 iBooster from a Jaguar iPace, but the physical packaging just wasn't going to work in the end - too much interference with surrounding bodywork.
I ended up choosing the Gen2 iBooster from a Yaris firstly because the packaging more naturally suits the MX5 engine bay. The booster-bulkhead interface is also the same as MX5 factory (80x60 M8), so no adapter plate is required. The pushrod is also directly usable, albeit with a new clevis for the pedal (M8, short, trimmed slightly to allow use of a locking nut).
On the other side of the booster, things are slightly complicated by the master cylinder being clocked 22.5° (anticlockwise from vertical). The stock reservoir from the Yaris allows for this by having it's connection to the master cylinder clocked to match, but unfortunately this reservoir doesn't fit in the MX5. This part of the conversion is currently tbd.
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. The brake line connections are M12x1 DIN bubble flare on both ports. In an effort to minimise fabrication, I'm using the fact that the factory MX5 has a joint in the hardlines just before the reach the master cylinder. This means that the only custom brake lines I need are the two short runs from the master cylinder outlet ports to the factory joint (3/16 cunifer line with M12x1 DIN bubble on one end, M10x1 double inverted flare on the other, bent to suit).
I should also point out that I had to drill out the 8mm mounting holes on the master cylinder to 10mm. This is because this particular master cylinder has a mounting stud spacing of 102mm whereas the iBooster studs are 100mm spaced. This solves that problem, and since there is an additional mounting plate for the hardline, which will act as washers/spreaders for the stud nuts, I am comfortable with this mod.
More info and pics to follow shortly.
Chris
For my own project, I'm taking the long approach to one day electrifying a 2003 Mazda MX5 (NB2.5). It's not my daily driver but I do want it off the road for as little time as possible. I'm therefore tackling as many small jobs as possible ahead of the conversion. One such job is deciding what to do about the factory vacuum brake booster. I don't like the idea of standalone vacuum pumps, and I'm not keen on de-assisting the brakes either, so the electric booster option is an option I want to explore.
Firstly, I did try a Gen1 iBooster from a Jaguar iPace, but the physical packaging just wasn't going to work in the end - too much interference with surrounding bodywork.
I ended up choosing the Gen2 iBooster from a Yaris firstly because the packaging more naturally suits the MX5 engine bay. The booster-bulkhead interface is also the same as MX5 factory (80x60 M8), so no adapter plate is required. The pushrod is also directly usable, albeit with a new clevis for the pedal (M8, short, trimmed slightly to allow use of a locking nut).
On the other side of the booster, things are slightly complicated by the master cylinder being clocked 22.5° (anticlockwise from vertical). The stock reservoir from the Yaris allows for this by having it's connection to the master cylinder clocked to match, but unfortunately this reservoir doesn't fit in the MX5. This part of the conversion is currently tbd.
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. The brake line connections are M12x1 DIN bubble flare on both ports. In an effort to minimise fabrication, I'm using the fact that the factory MX5 has a joint in the hardlines just before the reach the master cylinder. This means that the only custom brake lines I need are the two short runs from the master cylinder outlet ports to the factory joint (3/16 cunifer line with M12x1 DIN bubble on one end, M10x1 double inverted flare on the other, bent to suit).
I should also point out that I had to drill out the 8mm mounting holes on the master cylinder to 10mm. This is because this particular master cylinder has a mounting stud spacing of 102mm whereas the iBooster studs are 100mm spaced. This solves that problem, and since there is an additional mounting plate for the hardline, which will act as washers/spreaders for the stud nuts, I am comfortable with this mod.
More info and pics to follow shortly.
Chris
Re: Yaris Gen4 iBooster Gen2
Also you can see the hardline joint, the brass thing next to the master cylinder with the two factory lines connected to its top. The factory joint doesn't quite work in this application, so this brass block is a brake line joint from a Subaru Forester.
Better view of a small bracket used to mount the joint in the hardlines.
The trimmed M8 clevis joint.
Possible reservoir from a Mini R56, but requires an adapter to change the mounting angle. I'm awaiting a mock 3D print to test fit, but of course this would need to be something like machined aluminium to be properly functional.
Re: Yaris Gen4 iBooster Gen2
On the wiring, after some searching and an eventual defeat by paywall, I have purchased the wiring manuals for the Yaris MK4. They reveal that the wiring is not the same on the Yaris as it is in other iBooster Gen2 applications.
Interestingly, there is a "Brake Control Power Module" (89680-K0010) which appears to be an emergency back-up power source for the iBooster in the event of power failure in the vehicle. I have not seen this in other conversions, but at £35 off fleabay I thought it would be something worth having. Currently awaiting delivery for test-fitting. This module connects to pin 17 on the iBooster (usually an unused pin on the Gen2, according to other guides) along with a few others (see pinouts below).
There are also connections to the door-open vanity light switches and to the stop light circuitry. Since I will be keeping the stock MX5's brake wiring with its pedal switch, I will probably not make any use of this.
It's also worth noting (as others have elsewhere) that the pedal travel sensor connector pins on the Yaris iBooster are in reversed order compared to normal.
Yaris iBooster Gen2
Connector: 82824-K0100
Bosch "EuCon" 26p
01: +12V 40A fused permanent live
02: Pedal Travel Sensor (pin 3)
03: -
04: CLIN (to pin 2 on BCPM)
05: -
06: -
07: -
08: Pedal Travel Sensor (pin 1)
09: GND
10: CAN1 L
11: -
12: -
13: -
14: -
15: CTY (door courtesy light switch)
16: CAN2 L
17: CBKP (to pin 6 on BCPM)
18: CAN1 H
19: -
20: IGR switched, 5A fused, hot in run/start
21: STP (stop light circuit)
22: Pedal Travel Sensor (pin 4)
23: Pedal Travel Sensor (pin 2)
24: CWKP (to pin 3 on BCPM)
25: CAN2 H
26: -
Pedal Travel Sensor
Connector: 82824-K0120
TE MQS (4 pin)
01: iBooster pin 8
02: iBooster pin 23
03: iBooster pin 2
04: iBooster pin 22
Brake Control Power Module (89680-K0010) (BCPM)
Connector: 90980-12785
01: +12V 10A fused permanent live
02: LIN (iBooster pin 4)
03: WKUP (iBooster pin 24)
04: GND
05: -
06: OUT (iBooster pin 17)
Interestingly, there is a "Brake Control Power Module" (89680-K0010) which appears to be an emergency back-up power source for the iBooster in the event of power failure in the vehicle. I have not seen this in other conversions, but at £35 off fleabay I thought it would be something worth having. Currently awaiting delivery for test-fitting. This module connects to pin 17 on the iBooster (usually an unused pin on the Gen2, according to other guides) along with a few others (see pinouts below).
There are also connections to the door-open vanity light switches and to the stop light circuitry. Since I will be keeping the stock MX5's brake wiring with its pedal switch, I will probably not make any use of this.
It's also worth noting (as others have elsewhere) that the pedal travel sensor connector pins on the Yaris iBooster are in reversed order compared to normal.
Yaris iBooster Gen2
Connector: 82824-K0100
Bosch "EuCon" 26p
01: +12V 40A fused permanent live
02: Pedal Travel Sensor (pin 3)
03: -
04: CLIN (to pin 2 on BCPM)
05: -
06: -
07: -
08: Pedal Travel Sensor (pin 1)
09: GND
10: CAN1 L
11: -
12: -
13: -
14: -
15: CTY (door courtesy light switch)
16: CAN2 L
17: CBKP (to pin 6 on BCPM)
18: CAN1 H
19: -
20: IGR switched, 5A fused, hot in run/start
21: STP (stop light circuit)
22: Pedal Travel Sensor (pin 4)
23: Pedal Travel Sensor (pin 2)
24: CWKP (to pin 3 on BCPM)
25: CAN2 H
26: -
Pedal Travel Sensor
Connector: 82824-K0120
TE MQS (4 pin)
01: iBooster pin 8
02: iBooster pin 23
03: iBooster pin 2
04: iBooster pin 22
Brake Control Power Module (89680-K0010) (BCPM)
Connector: 90980-12785
01: +12V 10A fused permanent live
02: LIN (iBooster pin 4)
03: WKUP (iBooster pin 24)
04: GND
05: -
06: OUT (iBooster pin 17)
Re: Yaris Gen4 iBooster Gen2
I need to put the wiring loom together and get the hardlines flared, then I will do some CANBUS sniffing and experimentation with the additional inputs and outputs, then I'll post an update 

- manny
- Posts: 92
- Joined: Sun Jan 23, 2022 4:15 pm
- Location: Netherlands
- Has thanked: 22 times
- Been thanked: 61 times
Re: Yaris Gen4 iBooster Gen2
I am using the same ibooster from a yaris in my project. To get is to work in failsafe mode I needed to add 120 Ohm resistors to the CAN busses. And than power, ground and ignition.
Found the connector for the sensor on aliexpress
https://nl.aliexpress.com/item/1005004072725751.html
The connector is still on its way. So I am not a 100% that it will fitt.
Found the connector for the sensor on aliexpress
https://nl.aliexpress.com/item/1005004072725751.html
The connector is still on its way. So I am not a 100% that it will fitt.
Re: Yaris Gen4 iBooster Gen2
Ah thanks for the hint. Were there any messages required to kick it into life, or simply the 120ohm termination?
I was lucky enough to receive the pedal position sensor connector (and it's mini-loom) with the iBooster when I bought it, but I've had to source the main connector and terminals/seals elsewhere.
I was lucky enough to receive the pedal position sensor connector (and it's mini-loom) with the iBooster when I bought it, but I've had to source the main connector and terminals/seals elsewhere.
Re: Yaris Gen4 iBooster Gen2
Also, I've been wondering about this "failsafe" mode which is also mentioned. I understand that the theory is that if the CAN signals are absent, the unit will work in this "failsafe" mode, but from what I can tell, other than some diagnostics and the ability to remote-control the pedal, I'm not sure I understand what's really different. I imagine the calibration/assist curve is unchanged, and it's not running reduced power like certain electric power steering pumps do..?
- manny
- Posts: 92
- Joined: Sun Jan 23, 2022 4:15 pm
- Location: Netherlands
- Has thanked: 22 times
- Been thanked: 61 times
Re: Yaris Gen4 iBooster Gen2
Yes, it sends canbus but it's not needed to received or answer.
Don't know about the power level. Assist curve and remote control of the brake can probably be controlled via CAN
Re: Yaris Gen4 iBooster Gen2
Excellent, thanks.

I'm hoping to be able to contribute on this one at least - part of my team at work handles ADAS simulation, so they are all over CAN signals and debugging. Hopefully I can get something useful from them

Re: Yaris Gen4 iBooster Gen2
Update on the reservoir - after further browsing and googling, I've found that the reservoir from a VW Golf Mk7 or Passat B8 (LHD version) not only matches the clocking of the Yaris master cylinder, but fits the package space I have and has the fluid level sensor on the convenient side of the reservoir. The part number is 5QE611301.
All I need to do is find one... Since I live in the UK I need to search overseas for this reservoir. I've got leads on a couple but the postage is more than the cost of the item itself. :/ Will have to pull some strings with my EU-based colleagues at work.
All I need to do is find one... Since I live in the UK I need to search overseas for this reservoir. I've got leads on a couple but the postage is more than the cost of the item itself. :/ Will have to pull some strings with my EU-based colleagues at work.
Re: Yaris Gen4 iBooster Gen2
I have received the Brake Control Power Module
cute little thing that it is.
It's roughly 14 x 12 x 5 centimeters.
I've found a convenient place it, right next to the iBooster, tucked under the wing;
There are three less-than-perfect-but-probably-okay existing mounting points nearby, all on the main fusebox bracketry. I'm drafting up a cardboard template for the mounting plate as we speak.
I was careful to order one with the connector, here it is with pins half-way removed;
The connector is as follows;
Connector: 90980-12785
Terminals;
Sumitomo TS sealed series
8100-0461 (0.5-1.25mm²) (3off)
8100-0462 (2mm² max) (2off)
Pinouts;
01: +12V 10A fused permanent live
02: LIN (iBooster pin 4)
03: WKUP (iBooster pin 24)
04: GND
05: -
06: OUT (iBooster pin 17)
I've bought new terminals and am just waiting for some new wiring to come through the post

It's roughly 14 x 12 x 5 centimeters.
I've found a convenient place it, right next to the iBooster, tucked under the wing;
There are three less-than-perfect-but-probably-okay existing mounting points nearby, all on the main fusebox bracketry. I'm drafting up a cardboard template for the mounting plate as we speak.
I was careful to order one with the connector, here it is with pins half-way removed;
The connector is as follows;
Connector: 90980-12785
Terminals;
Sumitomo TS sealed series
8100-0461 (0.5-1.25mm²) (3off)
8100-0462 (2mm² max) (2off)
Pinouts;
01: +12V 10A fused permanent live
02: LIN (iBooster pin 4)
03: WKUP (iBooster pin 24)
04: GND
05: -
06: OUT (iBooster pin 17)
I've bought new terminals and am just waiting for some new wiring to come through the post

Re: Yaris Gen4 iBooster Gen2
I'll be sniffing LIN and WKUP as soon as possible - I'm intrigued. The +12V and GND are obvious of course, and OUT seems to be the line for providing working power to the iBooster in case of a power cut. The other two must be to do with identifying a power cut condition but I'm just guessing.
An internal wiring diagram would be useful, but I doubt I'll find one - these things are normally proprietary "black-boxes". At ~£30 a pop, I might buy a second one to tear apart if sniffing is unsuccessful.
An internal wiring diagram would be useful, but I doubt I'll find one - these things are normally proprietary "black-boxes". At ~£30 a pop, I might buy a second one to tear apart if sniffing is unsuccessful.
Re: Yaris Gen4 iBooster Gen2
A small amount of "exciting news";
I ended up buying a whole iBooster/master cylinder from Lithuania for ~£110 just for the reservoir
At least I've got it now, and it fits like a glove in the car
. I can also sell off the iBooster and reservoir-less master cylinder on the bay to make the money back.
As you can see, progress on the car has been nil since we've been snowed in. Tonight I worked up the bravery to break the ice to open the door in order to open the bonnet.
Also received the new wires today to make up the iBooster mini-loom. Just need to wait for the snow to melt a bit so I can get into my shed and retrieve my crimpers
I've also got as far as I can with the cardboard template for the power module bracket. I'm hoping it'll warm up a bit tomorrow so I can go out and draft it up in the car.
I ended up buying a whole iBooster/master cylinder from Lithuania for ~£110 just for the reservoir


As you can see, progress on the car has been nil since we've been snowed in. Tonight I worked up the bravery to break the ice to open the door in order to open the bonnet.
Also received the new wires today to make up the iBooster mini-loom. Just need to wait for the snow to melt a bit so I can get into my shed and retrieve my crimpers

I've also got as far as I can with the cardboard template for the power module bracket. I'm hoping it'll warm up a bit tomorrow so I can go out and draft it up in the car.
- manny
- Posts: 92
- Joined: Sun Jan 23, 2022 4:15 pm
- Location: Netherlands
- Has thanked: 22 times
- Been thanked: 61 times
Re: Yaris Gen4 iBooster Gen2
After 3 weeks of delay my package finally arrived. I can confirm that the connector fits fine.