Difficulty: Easy
Correct Answer: failure of the primary or secondary circuit of hydraulic system
Explanation:
Introduction / Context:
Modern vehicles include a red brake warning lamp tied to safety-critical sensors. Interpreting what triggers this lamp is essential for correct troubleshooting and avoiding unsafe operation.
Given Data / Assumptions:
Concept / Approach:
The key safety function is to warn of hydraulic failure in either circuit (front/rear or diagonal split). A pressure differential switch moves if one circuit loses pressure, closing the warning circuit. Low fluid level (often due to leaks) may also trigger the lamp; both are manifestations of hydraulic system failure risk.
Step-by-Step Solution:
Identify the lamp: red “BRAKE” or exclamation symbol.Check for pressure differential or reservoir level signal that indicates a failed circuit.Therefore, the lamp primarily signals failure of a primary or secondary hydraulic circuit.
Verification / Alternative check:
Confirm by scanning the vehicle manual or wiring diagram: the lamp connects to the differential pressure switch and fluid level sensor; test by opening a bleed screw on one circuit and observing lamp behavior.
Why Other Options Are Wrong:
Water contamination is not directly sensed.
Air in lines may cause a soft pedal but is not directly detected by a simple switch.
Power-brake (vacuum/booster) failures often have a separate indicator or different symptoms.
Parking brake engagement can light the same lamp but is not the primary safety fault referenced in hydraulic warning systems.
Common Pitfalls:
Ignoring a lit brake lamp due to a slightly engaged parking brake; always verify fluid level and circuit integrity. Do not drive if pedal travel increases or car pulls to one side.
Final Answer:
failure of the primary or secondary circuit of hydraulic system
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