Automobile & Light Truck Certification Test A5 Brakes flashcards

A fault code (e.g., C0110) indicating an issue with the electrical circuit or internal components of the ABS hydraulic pump motor.

• Often points to problem within the ABS HCU (integral design).
• Requires verifying external power/ground before internal diagnosis.
• Can prevent ABS/ESC from functioning correctly.

Memory trick: C0110: The Pump Motor is a NO-GO!

A brake booster failure or loss of vacuum supply results in a 'hard pedal' symptom, requiring significantly increased effort to apply the brakes.

• Brake booster multiplies pedal force.
• Relies on engine vacuum (or electric pump).
• Failure causes a firm, high pedal with high effort.

Memory trick: Hard pedal? Think vacuum loss or booster's boss.

A bulging or swollen flexible brake hose indicates internal damage, causing it to expand under pressure, which leads to a spongy pedal and reduced braking efficiency.

• Internal layers have failed.
• Absorbs hydraulic pressure.
• Causes spongy pedal and potentially uneven braking.

Memory trick: A bulge in the hose means a spongy path, losing pressure in its wrath.

Brake fluid degrades over time and with excessive heat exposure, leading to reduced boiling point, loss of lubricating properties, and potential system damage.

• Heat is the primary cause of degradation.
• Degraded fluid can appear dark or burnt-smelling.
• Reduces braking efficiency and can cause component failure.

Memory trick: Hot fluid smells burnt, looks dark, and loses its spark.

A wheel cylinder can leak internally onto brake shoes within a drum brake, making the fluid loss not externally visible, but still causing a low fluid level and soft pedal.

• Fluid absorbed by shoes or evaporates.
• Causes fluid loss and can introduce air.
• Requires drum removal for inspection.

Memory trick: Hidden fluid loss? Check the drum's inner boss.

An internal bypass in the master cylinder occurs when fluid leaks past the piston seals, preventing immediate pressure buildup and causing a spongy pedal that may firm up after multiple pumps.

• Pedal sinks slowly or feels spongy.
• Often improves with rapid pumping.
• No external fluid loss typically.

Memory trick: Pumping up a spongy pedal points to a master cylinder's internal seal's downfall.

An improperly formed brake line flare (uneven, cracked, or off-center) will not create a leak-proof seal, leading to brake fluid loss.

• Crucial for hydraulic integrity.
• Requires proper tools and technique.
• Failure results in leaks and potential brake failure.

Memory trick: A bad flare means a sure leak, no more brake power to speak.

Electrically controlled valves within the ABS HCU that modulate brake fluid pressure to individual wheels during ABS, TCS, or ESC events.

• Inlet valves control pressure application to the wheel.
• Outlet valves control pressure release from the wheel.
• Work in conjunction with the pump and accumulator.

Memory trick: Inlet IN, Outlet OUT, Pump POWER, Accumulator STOUT!

The vacuum booster check valve holds vacuum in the booster when the engine is off, ensuring power assist for a few brake applications after shutdown.

• Located on the vacuum booster where the hose connects.
• Allows air to be drawn out of the booster but prevents it from re-entering.
• Failure leads to loss of vacuum reserve when engine is off.

Memory trick: Vacuum valve's seal, ensures the pedal's feel, even when the engine's off, it's a critical deal.