* Weak or corroded battery cables: Even with a new battery, corroded or loose connections at the battery terminals, or anywhere along the positive (+) and negative (-) cables, can prevent sufficient current flow. Clean and tighten all connections thoroughly. Check the cables themselves for damage or significant wear.
* Starter motor: The starter motor itself could be failing. It might be drawing too much current or have internal problems preventing it from engaging properly. This is a common failure point in older vehicles. Testing the starter motor or having it tested by an auto parts store is recommended.
* Ignition switch: The ignition switch could be faulty, preventing proper power from reaching the starter solenoid. This is less likely given you've replaced the relay, but it's still a possibility.
* Solenoid: The starter solenoid (a part of the starter motor assembly, or sometimes a separate unit) is responsible for engaging the starter motor. A failing solenoid will often produce a clicking sound. It's possible the new relay didn't address a problem with the solenoid itself.
* Wiring harness: Damaged or corroded wiring in the harness between the battery, ignition switch, and starter motor can create intermittent problems like the one you're experiencing. A thorough visual inspection of the harness is needed, looking for broken wires, corrosion, or poor connections.
* Neutral safety switch (automatic transmission): If your Cougar has an automatic transmission, the neutral safety switch prevents the starter from engaging unless the transmission is in Park or Neutral. A faulty switch can prevent the car from starting.
Troubleshooting Steps:
1. Thoroughly clean and tighten all battery and cable connections: This is the easiest and cheapest check and often solves the problem. Use a wire brush and baking soda/water paste to clean the terminals.
2. Check the starter motor: Have it load tested at an auto parts store. This will determine if it's drawing excessive current or failing to turn properly.
3. Inspect the wiring harness: Pay close attention to the areas around the battery, starter motor, and ignition switch. Look for any signs of damage or corrosion.
4. Test the ignition switch (if you have experience with electrical testing): This is more complex and may require a wiring diagram.
5. Check the neutral safety switch (automatic transmission): See if the car starts when you manually move the shifter to different positions.
If you're not comfortable performing these checks yourself, take the car to a qualified mechanic. They have the tools and expertise to diagnose the problem accurately and efficiently. Describing the intermittent nature of the problem is crucial for helping them pinpoint the cause.
