ASE G1 Auto Maintenance and Light RepairElectrical/Electronic SystemsMedium
A technician is performing a parasitic draw test. With the ignition off and all accessories off, the multimeter shows a current draw of 250 milliamperes (mA) after waiting for the vehicle's modules to 'go to sleep'. What should the technician do next?
- ACheck for continuity in the starter motor circuit.
- BDisconnect the battery and charge it overnight.
- CBegin pulling fuses one at a time to isolate the circuit causing the draw.
- DStart the engine and check the charging system output.
Show answer & explanationAnswer & explanation
Correct answer: C. Begin pulling fuses one at a time to isolate the circuit causing the draw.
A parasitic draw of 250 mA is significantly higher than the acceptable range (typically 20-50 mA). The next step is to systematically isolate the circuit causing the draw by pulling fuses until the current drops to an acceptable level.
Why the other options are wrong
- A. Checking the starter circuit continuity is not relevant to diagnosing a parasitic draw when the vehicle is off.
- B. Charging the battery only addresses the symptom, not the underlying cause of the draw.
- D. Checking the charging system is unrelated to a parasitic draw when the vehicle is off.
Parasitic Draw Test
A test to measure the amount of electrical current drawn from the battery by vehicle components when the ignition is off, used to diagnose unexplained battery discharge.
- Normal draw is typically 20-50 mA.
- Excessive draw indicates a faulty component.
- Fuses are pulled to isolate the circuit.
Memory trick: Find the 'leak' draining the battery.