A technician is diagnosing a vehicle with an intermittent 'no-crank' condition. The battery tests good, and all main battery cables show acceptable voltage drops. When attempting to start, sometimes there is a single click, and sometimes there is no sound at all. Which component is most likely causing this intermittent issue?
- AA seized engine.
- BA faulty starter motor armature.
- CAn open circuit in the starter motor's field windings.
- DAn intermittently failing neutral safety switch.
Show answer & explanationAnswer & explanation
Correct answer: D. An intermittently failing neutral safety switch.
An intermittently failing neutral safety switch (or range sensor) can cause both 'no-click' (if the circuit isn't completed) and 'click, no-crank' (if it intermittently allows enough current to energize the solenoid but not fully close the main contacts or if the solenoid is weak) conditions depending on its internal contact condition at the time of starting, making it a common cause for intermittent starting issues in the control circuit.
Why the other options are wrong
- A. A seized engine would consistently cause a 'click, no-crank' condition and is not intermittent.
- B. A faulty starter motor armature would consistently cause a 'click, no-crank' or 'slow crank' if it was partially shorted, not an intermittent no-click.
- C. An open in the field windings would consistently cause a 'click, no-crank' condition.
Intermittent No-Crank Diagnosis
Troubleshooting a starting problem that does not occur consistently, often pointing to a component in the control circuit that is sensitive to position, temperature, or vibration.
- Can manifest as 'no-click' or 'click, no-crank' intermittently.
- Common culprits include neutral safety switch, ignition switch, starter relay, and loose/corroded control circuit connections.
- Requires careful testing under various conditions to replicate the fault.
Memory trick: Sometimes it starts, sometimes it's dead, the control circuit's in your head.