* Weak or failing battery: This is the most common cause. A battery that can't deliver enough amperage will cause the lights to dim or flicker under load (like trying to crank the engine). The ticking noise could be the starter motor struggling to engage due to insufficient power. Get the battery load tested at an auto parts store.
* Bad battery cables/connections: Corroded, loose, or damaged battery cables (positive and negative) will restrict current flow. Clean and tighten the connections at both the battery and engine terminals. Inspect the cables for damage; replace if necessary.
* Failing starter motor: The ticking sound could be the starter solenoid clicking but not engaging the starter gear. A failing starter motor might be drawing excessive current, causing the voltage drop.
* Alternator problems: While the alternator primarily charges the battery, a failing alternator *might* not be providing enough charge while the engine is running, leading to insufficient power for cranking when the battery is already low. This is less likely to be the primary cause of your problem, but should be checked if the battery and connections are fine.
* Poor ground connections: A poor ground connection somewhere in the electrical system can cause similar symptoms. This is harder to diagnose and often requires tracing the wiring.
* Wiring harness issues: While less likely, a damaged or corroded wire in the main power feed to the starter or the battery can cause intermittent power problems.
Troubleshooting Steps:
1. Check the battery: Have it load tested at an auto parts store. A visual inspection for corrosion on the terminals is also important.
2. Clean and tighten battery cables: This is a quick and easy check that often solves the problem.
3. Check the starter: If the battery and cables are good, the starter itself may be failing. This often requires a professional diagnosis or replacement.
4. Check the alternator (if battery is charged): If the battery shows a good charge but the problem persists, have the alternator tested.
5. Check ground connections: This is more involved and may require some electrical knowledge.
Important Note: Don't continue trying to crank the engine repeatedly if the battery is weak. This can further drain the battery and potentially damage the starter motor. If you suspect a weak battery, jump-starting the vehicle might help determine if the problem is indeed battery-related. However, if jump-starting doesn't resolve the issue, it points to a problem beyond the battery.
