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PROCEDURE FOR SERVICING AND REPLACING THE IBOOSTER

I. Introduction

In recent years, there has been a tremendous development of so-called assistance systems that increase the safety and comfort of driving and the popularisation of electric and hybrid vehicles. The development and implementation of new technologies is most often associated with changing the existing solutions due to emerging limitations. 

 

Over the years, manufacturers used vacuum to control many actuators (e.g. turbocharger control) and to increase braking power.  Huge requirements and market trends, including popularised electric and hybrid vehicles, forced the introduction of a new type of system, e.g. the BOSCH electromechanical brake booster iBooster [Fig. 1.]. Note that this is the second generation of the brake booster that is produced in Poland. This system is installed, among others, in Volkswagen AG, TESLA and PORSCHE vehicles. Functions that can be implemented thanks to this solution include:

 

  • regenerative braking,
  • automatic, 3 times faster and more accurate pressure build-up using the electronic brake booster, without the driver having to press the brake pedal.

 

Each technological change brings challenges and potential additional problems for independent workshops when servicing or repairing. The process of replacing or disassembling the BOSCH iBooster brake booster requires following procedures in order to ensure correct operation of the system after external interference. In order to bring this issue closer, the article presents the iBooster replacement procedure carried out on the VW Arteon vehicle.

Fig. 1. BOSCH 2nd generation iBooster brake booster.
Fig. 1. BOSCH 2nd generation iBooster brake booster. 
II. Construction
The second generation of the BOSCH iBooster electronic brake booster has undergone significant design changes, e.g. a parallel drive responsible for boosting the power assist has been used. The booster element is responsible for generating the supporting force, activated by a brushless electric motor, with a power of up to 450 W, through a toothed gear made of plastic. The Hall effect brake pedal position sensor is no longer a replaceable external element, it has been moved inside the module [Fig. 2.].  
Fig. 2. Internal construction BOSCH 2nd generation iBooster brake booster.
Fig. 2. Internal construction BOSCH 2nd generation iBooster brake booster. 
III. Spare parts overview
In the presented example vehicle, as of the date of preparation of the article, Volkswagen AG allows the replacement of the complete 2nd generation iBooster brake booster. It is not possible to replace the position sensor, electric motor controller, transmission elements or parts of the booster element separately. According to the catalogue, spare parts include, among others: a two-section master cylinder, a fluid level sensor or a brake fluid reservoir cap. 
Fig. 3. List of brake booster parts 1- brake booster, 2- two-section master cylinder,
Fig. 3. List of brake booster parts 1- brake booster, 2- two-section master cylinder,
IV. Diagnostics

The iBooster electromechanical brake booster has a separate diagnosable control module. Fig.4. shows the possibilities that are available in the ESI [tronic] 2.0 diagnostic software by Bosch [Fig. 4]. Among other things, the following are possible:

  • Control module identification
  • Reading and erasing of the error memory record 

 

During the replacement/diagnosis of this system at Volkswagen AG, additional procedures are required, not included in the universal software (Fig. 5.), such as:

 

  • Brake booster control module coding
  • Bleeding of the brake booster
  • Checking operation with resistances
  • Pressure check

 

In this area, independent workshops have the option to use diagnostics using the vehicle manufacturer’s factory software, with the support of the standard SAE J2534 with Pass-thru interface (this was described in detail in the article “Pass Thru group VW, Audi, Seat, Skoda”).

Fig. 4. ESI [tronic] 2.0. Overview of diagnostic options for the iBooster electromechanical brake booster
Fig. 4. ESI [tronic] 2.0. Overview of diagnostic options for the iBooster electromechanical brake booster
Fig. 5. Offboard Diagnostic Information System Service. Overview of diagnostic options for the iBooster electromechanical brake booster
Fig. 5. Offboard Diagnostic Information System
Service. Overview of diagnostic options for the iBooster electromechanical
brake booster
V. Replacement

Replacing the brake booster requires the workshop to perform procedures through the Offboard Diagnostic Information System Service (ODIS) software. As mentioned earlier, this component has a separate control module. After removing the damaged electromechanical brake booster module and installing a new one, perform the following functions using a diagnostic proof point: 

 

a) Coding of brake booster control module -J539-. 

 

b) Bleeding the brake booster.In order to effectively bleed the system, the following conditions must be met:

 

  • Brake system filled and bled 
  • Brake fluid reservoir filled
  • Brake bleeding device connected to the vehicle
  • Parking brake released
Fig. 6. Offboard Diagnostic Information System Service. iBooster brake booster bleeding procedure - prerequisites
Fig. 6. Offboard Diagnostic Information System
Service. iBooster brake booster bleeding procedure - prerequisites

Next, start the connected device for bleeding the brake system, set the working pressure in the range of 1.5 to 2.5 bar, unscrew the left front brake caliper bleeder and the right front brake caliper bleeder until no air bubbles appear in the hose from the used brake fluid reservoir.

 

In the next part of the program, the brake booster will be bled. Remove all objects from the driver’s footwell due to the program automatically activating the brake lever check. In the next steps, we are asked to unscrew the vent of the indicated brake caliper and confirm its readiness and then close it [Fig. 7].  

Fig. 7. Offboard Diagnostic Information System Service. iBooster brake booster bleeding procedure
Fig. 7. Offboard Diagnostic Information System
Service. iBooster brake booster bleeding procedure
The next process after bleeding the system is automatic start-up, operation check. This function monitors the operation of the electromechanical brake booster and compares it with the values stored in the software.
Fig. 8. Offboard Diagnostic Information System Service. Procedure for bleeding the iBooster brake booster - operation check.
Fig. 8. Offboard Diagnostic Information System
Service. Procedure for bleeding the iBooster brake booster - operation check.
If all functions are carried out correctly and no errors are recorded during their execution, the iBooster replacement procedure has been carried out correctly.