Practice Test Geeks(MST) Marine Service Technician Practice Test
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Electrical Systems & Troubleshooting Flashcards

7 cards from real MST practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Electrical Systems & Troubleshooting flashcards as text

  1. What does a voltage drop test across a circuit component indicate when the reading is higher than specified?

    Answer: Excessive resistance exists in that part of the circuit

    A high voltage drop across a component indicates excessive resistance, which can be caused by corrosion, loose connections, or a failing component.

  2. When testing a marine alternator's output, you should connect the voltmeter's positive lead to the alternator's output terminal and the negative lead to:

    Answer: The alternator case ground

    The negative lead goes to the alternator case ground to measure the actual output voltage at the alternator itself.

  3. A marine engine's starter motor cranks slowly. After fully charging the battery, the problem persists. What is the MOST likely cause?

    Answer: High resistance in the starter circuit

    High resistance from corroded cables, loose connections, or a failing solenoid causes excessive voltage drop, reducing current flow to the starter.

  4. What is the primary purpose of a bilge pump float switch circuit's fuse protection?

    Answer: To protect the boat's wiring from short circuits in the bilge pump circuit

    The fuse protects the vessel's wiring from damage caused by a short circuit in the bilge pump circuit, preventing fire hazards.

  5. A marine technician is diagnosing an intermittent electrical fault. Which tool is BEST suited for capturing the fault as it occurs?

    Answer: Digital multimeter with MIN/MAX recording function

    A digital multimeter with MIN/MAX recording captures brief voltage spikes or drops that occur during intermittent faults.

  6. What is the correct wire gauge to use when replacing a 20-foot (one-way) 12V DC circuit that must carry 20 amps on a marine vessel?

    Answer: 10 AWG

    ABYC standards require 10 AWG for a 20-amp circuit with a 20-foot run to keep voltage drop within the 3% maximum allowance.

  7. On a marine vessel, why are bonding wires connected to through-hulls and metal underwater fittings?

    Answer: To equalize electrical potential and prevent galvanic corrosion

    Bonding equalizes the electrical potential between underwater metal fittings, preventing galvanic corrosion caused by dissimilar metals in an electrolyte.