Wiring
Wiring the iBooster is fairly straight forward. The booster has two Bosch connectors on its body. One connector is for the pedal travel sensor (4-pins), the main connector is a 26-pin connector for power and signal. The main connects to 12V+ (permanent, no relay), Ground and a 12V+ from the ignition and the travel pedal sensor.
There are connector kits available for the iBooster which include the Bosch connectors, pins and seals required. You can get away installing the booster without the official connectors but it does make for a cleaner install. The pins on the booster are standard car connectors. You will need the following three sizes: TODO: 1.5, 2.8 and 4.8 including seals. You can find the connector kit by searching for the Bosch part number 1928405762 (main connector) and 1928405525 (pedal travel sensor). Make sure you are getting the set for the Gen2 booster. The difference is that the 4-pin pedal travel sensor connector has the pins in a row instead of a two by two configuration.
| Main Connector | Terminal Size | Pedal Sensor Connector | Car |
|---|---|---|---|
| 22 | 1.5x0.6FS | 1 | |
| 2 | 1.5x0.6FS | 2 | |
| 23 | 1.5x0.6FS | 3 | |
| 8 | 1.5x0.6FS | 4 | |
| 1 | 4.8x0.8FS | Ground | |
| 9 | 4.8x0.8FS | 12V+ | |
| 20 | 1.5x0.6FS | Ignition |
I recommend that you bench-test the booster before installing it in the car. Since they are used, you want to make sure they operated properly. Take brake master cylinder off the booster before testing. You can run the booster off of a 12V power supply. The current draw is less than 2A when the brake master cylinder is not attached. Alternatively, you can just connect it the car battery for testing.
Start with connecting the travel pedal sensor
- Use four wires (11" 18 AWG, 28cm 0.75mm2)
- Mark the wires from 1 through 4 on both ends
- Wrap the wires in a sleeve or heat shrink
- Push the seals on the wire ends and crimp the terminals
- Connect the wires to the pedal sensor terminal
The following instructions are specific to the Mercedes W113 series (230SL, 250SL, 280SL). The fundamental wiring will be the same for all cars.
The Tesla wiring diagrams asks for a 40A fuse for the 12V wire. In my testing, the current did not exceeded 9A. I used 12 AWG wire (4mm2) for the ground and 12V+ wire. The 12V+ is directly connected to the battery. Alternatively, you can run a wire from the starter motor terminal, which is also unfused. I ran the wire to the auxiliary fuse box mounted next to the brake booster (and clutch fluid reservoir) and installed a 25A ceramic fuse (blue). From here, the wire runs to the booster.
For the ignition wire, I connected a 18 AWG (0.75mm2) wire to fuse 3 in the fuse box and ran it through the smaller grommet with the washer fluid tube. Double check that the fuse provides 12V+ only when the key is in position 2. Otherwise the booster will be powered on all the time which will drain the battery in no time. Since this wire is just a signal wire and doesn't carry much current. You should also be able to run a wire from the ballast resister of the coil.