ASE A1 Engine RepairEngine Electrical Systems (General)Easy
A technician is diagnosing a vehicle with an intermittent no-start condition. The battery tests good, and all accessories work. When the key is turned to the 'START' position, nothing happens—no click, no crank. Which of the following is the MOST likely cause?
- AA faulty alternator
- BLow engine oil pressure
- CA seized engine
- DAn open in the starter control circuit
Show answer & explanationAnswer & explanation
Correct answer: D. An open in the starter control circuit
If the battery is good and there's no click or crank when attempting to start, it indicates that the starter motor is not receiving power or the signal to engage. This points to an issue within the control circuit that activates the starter solenoid.
Why the other options are wrong
- A. A faulty alternator would primarily affect charging, not the initial cranking of the engine.
- B. Low engine oil pressure would not directly cause a 'no click, no crank' condition; it's a symptom that appears after the engine is running or attempting to run.
- C. A seized engine would typically result in a 'click' from the solenoid but no cranking, or a very slow, struggling crank.
Starter Control Circuit
The low-current circuit that activates the starter solenoid, which in turn allows high current to flow to the starter motor.
- Typically includes the ignition switch, neutral safety switch/clutch interlock switch, and starter relay.
- An open in this circuit prevents the starter solenoid from engaging.
- Symptoms of an open circuit are 'no click, no crank'.
Memory trick: Key turns, but nothing stirs, check the starter's silent words.