Quick answer
If your lights are bright but the car only clicks and won't crank, the battery has enough charge to power accessories but not enough cold cranking amps to turn the starter — or the starter itself, its solenoid, or the battery cables have a bad connection. Rapid clicking usually means a weak battery; a single loud click points to the starter.
Common causes
- A weak battery with enough voltage for lights but not enough to crank
- Corroded or loose battery terminals and cable ends limiting current
- A failed starter solenoid that engages but cannot turn the motor
- A bad ground cable between the battery and chassis or engine
How to diagnose it
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Check the battery voltage under load
Measure battery voltage while a helper turns the key. If it drops below 9.6 V during cranking, the battery is too weak to start the car.
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Clean and tighten the battery connections
Remove the cable clamps, clean the posts and clamp interiors with a brush, and retighten. Also check and clean the engine ground strap.
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Distinguish single click from rapid clicking
Rapid clicking indicates a weak battery or poor connection. A single solid click with no cranking points to the starter or its solenoid.
When to see a mechanic
- The battery tests good but the car still only clicks
- The starter is hard to access or requires removing other components
- There are no lights, dash, or clicking at all, suggesting a main fuse or cable
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