Automobile & Light Truck Certification Test A5 BrakesPower Assist Unit Diagnosis and RepairMedium
A vehicle equipped with an electric power brake booster (i-Booster) experiences intermittent loss of power assist and illuminates the 'Brake System' warning light. A scan tool reveals a DTC related to the booster's internal motor circuit. Which of the following is the MOST common repair strategy for such a component?
- ABleed the hydraulic brake system.
- BPerform a software reflash of the engine control module (ECM).
- CReplace the entire electric power brake booster assembly.
- DReplace only the electric motor within the booster.
Show answer & explanationAnswer & explanation
Correct answer: C. Replace the entire electric power brake booster assembly.
Electric power brake boosters, like the i-Booster, are highly integrated units. Internal motor circuit faults typically necessitate replacing the entire booster assembly, as individual components like the motor are usually not serviceable separately by technicians.
Why the other options are wrong
- A. Bleeding the system addresses hydraulic issues, not an electrical fault within the booster motor circuit.
- B. While software can sometimes cause issues, an internal motor circuit DTC points to a hardware failure within the booster, not an ECM software issue.
- D. Electric booster motors are generally not sold or serviced as individual components outside of the complete assembly.
Electric Power Brake Booster (i-Booster)
An integrated electro-mechanical unit that provides brake pedal assist and often incorporates ABS/ESC functions, replacing traditional vacuum or hydro-boost systems.
- Uses an electric motor for assist.
- Highly integrated unit.
- Internal faults often require full assembly replacement.
Memory trick: i-Booster's motor fault? It's a full assembly vault!