Automotive Service Excellence (ASE) A6 Electrical/Electronic SystemsStarting System Diagnosis and RepairMedium
A technician is diagnosing a vehicle that experiences a 'no-start' condition. When the key is turned to the START position, a single 'click' is heard from the engine compartment, but the starter motor does not engage. The battery has been tested and is fully charged. Which of the following is the most likely cause?
- AAn open circuit in the starter motor's field windings
- BA discharged battery
- CA faulty ignition switch
- DSeized starter motor bushings or bearings
Show answer & explanationAnswer & explanation
Correct answer: D. Seized starter motor bushings or bearings
A single 'click' with a fully charged battery often indicates that the starter solenoid is engaging but the starter motor itself cannot turn. This is commonly caused by mechanical binding within the starter, such as seized bushings or bearings, or issues with the armature.
Why the other options are wrong
- A. An open circuit in the field windings would prevent the starter from turning but would not necessarily cause a distinct 'click' from the solenoid engaging.
- B. A discharged battery would likely result in a rapid series of clicks (chattering solenoid) or no sound at all, not a single strong click.
- C. A faulty ignition switch would typically prevent even the 'click' or cause intermittent starting issues, not a consistent click without cranking.
Starter Motor Seizure
A condition where the internal components of the starter motor (e.g., bushings, bearings, armature) bind, preventing rotation despite solenoid engagement.
- Often indicated by a single 'click' from the solenoid with no cranking.
- Battery voltage will remain high during the 'click'.
- Requires starter motor replacement or rebuild.
Memory trick: The 'Click' means the switch is 'Quick', but the motor's 'Stuck'.