Automotive Service Excellence (ASE) A6 Electrical/Electronic SystemsGeneral Electrical/Electronic System DiagnosisEasy
A technician is diagnosing a complaint of a power window that operates slowly. The technician suspects excessive resistance in the power circuit. Which of the following tests should be performed FIRST to verify this suspicion?
- APerform a voltage drop test across the power and ground sides of the circuit while the window is operating.
- BCheck for continuity of the window motor's ground wire.
- CMeasure the current draw of the window motor with an inductive amp clamp.
- DInspect the window regulator for mechanical binding or obstruction.
Show answer & explanationAnswer & explanation
Correct answer: A. Perform a voltage drop test across the power and ground sides of the circuit while the window is operating.
A voltage drop test directly measures the resistance in a circuit under load, which is the most effective way to identify excessive resistance causing slow operation. High voltage drop indicates unwanted resistance.
Why the other options are wrong
- B. Continuity checks are good for 오픈 circuits, but a voltage drop test is better for high resistance under load.
- C. Measuring current draw can indicate a problem but doesn't pinpoint resistance location as directly as a voltage drop test.
- D. This addresses a mechanical issue, not an electrical resistance issue, and should be considered after electrical diagnosis.
Voltage Drop Test
A test that measures the voltage lost across a component or section of a circuit, indicating unwanted resistance under load.
- Performed with the circuit under load.
- Measures voltage difference between two points.
- High voltage drop indicates excessive resistance.
Memory trick: Voltage Drop Reveals Resistance's Hidden Hand in Slow Systems.