Automotive Service Excellence (ASE) A6 Electrical/Electronic SystemsStarting System Diagnosis and RepairMedium
A technician is diagnosing a no-crank condition on a vehicle. With the ignition key in the START position, the starter motor does not engage, but a single, loud click is heard from the engine compartment. All dashboard lights illuminate brightly. Which of the following is the most likely cause?
- AAn open circuit in the starter motor windings
- BCorroded or loose battery terminals
- CA discharged battery
- DA faulty starter solenoid
Show answer & explanationAnswer & explanation
Correct answer: D. A faulty starter solenoid
A single, loud click with bright dashboard lights indicates that the battery has sufficient power and the starter solenoid is attempting to engage but cannot pass high current to the starter motor. This is a classic symptom of a faulty starter solenoid.
Why the other options are wrong
- A. An open circuit in the starter motor windings would prevent the motor from turning, but the solenoid would still engage and pass current, potentially causing a click but usually not a single loud one without any further action.
- B. Corroded or loose battery terminals would typically cause dim lights and prevent sufficient current flow for the solenoid to engage properly, leading to rapid clicking or no sound.
- C. A discharged battery would likely result in dim or no dashboard lights and a rapid clicking sound, or no sound at all.
Starter Solenoid Failure
A common failure where the starter solenoid engages (clicks) but fails to pass high current to the starter motor, preventing engine cranking.
- Symptoms include a single, loud click from the engine compartment.
- Dashboard lights remain bright, indicating sufficient battery power.
- Engine does not crank or turn over.
Memory trick: Clicking bright lights, but no start, means the solenoid's part.