ASE G1 Auto Maintenance and Light RepairElectrical/Electronic SystemsMedium
A vehicle's power windows operate slowly, and the radio occasionally cuts out when the windows are operated. The battery and charging system test within specifications. What is the MOST likely cause of these symptoms?
- AA short circuit in the radio's power supply
- BExcessive resistance in the main power supply circuit
- CA faulty window motor on one of the doors
- DLow refrigerant in the air conditioning system
Show answer & explanationAnswer & explanation
Correct answer: B. Excessive resistance in the main power supply circuit
Slow power window operation and electrical accessory cutout when high-current accessories (like windows) are used, despite a good battery and charging system, are classic symptoms of excessive resistance or voltage drop in the main power supply circuit. This reduces the available voltage for all components.
Why the other options are wrong
- A. A short circuit in the radio's power supply would likely cause a fuse to blow or the radio to be completely inoperative, not intermittent cutouts when windows are used.
- C. A faulty window motor would primarily affect only that specific window, not cause other accessories to cut out.
- D. Low refrigerant in the A/C system would only affect A/C performance and has no direct relation to power window speed or radio operation.
Systemic Voltage Drop
Systemic voltage drop occurs when excessive resistance in a main power or ground circuit reduces the available voltage to multiple components, leading to sluggish operation or intermittent failures.
- Affects multiple electrical systems.
- Often related to main power or ground wires.
- Causes include corroded terminals, loose connections, damaged wires.
Memory trick: Voltage Drop: When resistance makes power 'drop' on its way.