* Weak Starter Motor: The most common cause. Even with power reaching the solenoid (the clicking sound), the starter motor's internal components might be worn out, corroded, or failing to engage the flywheel. This often manifests as a faint click, and a motor that struggles to turn over the engine. If you hear a *single* sharp click, this is often a strong indicator. Multiple clicks might mean a low battery, but in your case, you specified power at the relays.
* Bad Starter Solenoid: The solenoid is part of the starter motor. It's an electromagnet that engages the gear that meshes with the engine's flywheel. If the solenoid is faulty, it might click but not engage the motor fully.
* Corroded or Loose Connections: Check all the connections related to the starter motor. Corrosion on the battery terminals, the cables, the solenoid connection, or even the ground strap can prevent adequate current flow. Loose connections can cause intermittent problems like yours. Look for anything that looks green or is loose. Clean and tighten anything suspicious.
* Neutral Safety Switch (NSS): This switch prevents the engine from starting unless the transmission is in Park or Neutral. A faulty NSS can prevent the starter circuit from completing, even if power is reaching the relay. This will often prevent *any* clicking. But, if your transmission is in neutral or park, and you're still only hearing clicks, it's less likely.
* Low Battery Voltage (less likely given your statement): While you've indicated power, very low voltage *can* still lead to a click but no start even if you *feel* power at the relays. Use a voltmeter to check the battery voltage directly under load (while trying to crank). If the voltage drops significantly, it's a battery or charging system problem.
Troubleshooting Steps:
1. Check Battery Voltage: Use a multimeter to test the battery voltage both at rest and while attempting to start.
2. Inspect Cables and Connections: Carefully check all cables and connections from the battery to the starter motor and the relays, looking for corrosion, looseness, or damage. Clean and tighten any questionable connections.
3. Tap the Starter (carefully!): While someone attempts to crank the engine, gently tap the starter motor with a hammer or wrench. This is a risky step and only try it if you have basic mechanical knowledge and are comfortable with it. If this temporarily solves the problem, it suggests a worn starter motor.
4. Test the Starter Solenoid: This can be done with a jumper wire and a battery charger. (CAUTION: Requires some electrical knowledge and is dangerous if done improperly). If the solenoid isn't engaging, it's likely bad.
5. Check the Neutral Safety Switch: This often involves tracing wiring diagrams and testing continuity with a multimeter.
If you're not comfortable working on your vehicle's electrical system, it's best to take it to a qualified mechanic. Diagnosing starting problems can require specialized tools and experience. The clicking sound is a useful clue, but more investigation is needed to pinpoint the exact cause.
