1. The Most Likely Culprits:
* Faulty Radiator Fan Relay: This relay controls the power to the fan. A stuck relay will keep power flowing even after the ignition is off. Replacing this is often the cheapest and easiest fix.
* Bad Fan Control Module (PCM or ECM): The Powertrain Control Module (PCM) or Engine Control Module (ECM) (depending on the year) monitors engine temperature and controls the fan. A faulty module can send incorrect signals, keeping the fan running continuously. This is a more expensive repair.
* Faulty Temperature Sensor: An inaccurate temperature sensor might tell the PCM that the engine is still overheating, even when it's not, thus keeping the fan on.
2. Less Likely but Possible Causes:
* Shorted Wiring: A short circuit in the wiring harness leading to the fan or the relay can cause a constant power supply. This requires careful inspection of the wiring.
* Stuck Fan Switch: While less common, the fan's switch itself could be stuck in the "on" position.
* Low Coolant: Although less likely to cause the fan to *continuously* run after shutdown, severely low coolant can trigger the fan to run for an extended period as the system tries to cool down.
3. Troubleshooting Steps:
* Check the Coolant Level: Ensure your coolant level is within the normal range.
* Listen Carefully: Is the fan running at high speed or low speed? High speed often points to a problem with the temperature sensor or PCM.
* Locate the Radiator Fan Relay: Consult your owner's manual or an online repair manual to locate the relay. You can usually find it in the underhood fuse box. Try swapping it with a similar relay (if you have one readily available) to see if it resolves the issue. This is a good first step because relays are inexpensive and easy to replace.
* Inspect Wiring: Carefully examine the wiring harness leading to the fan and the relay for any signs of damage, fraying, or corrosion.
* Use a Multimeter (Advanced): If you're comfortable with electrical testing, a multimeter can help you check the voltage at the relay and the fan to identify if there's constant power flow.
4. When to Seek Professional Help:
If you're not comfortable working with automotive electrical systems, it's best to take your Stratus to a qualified mechanic. A faulty PCM/ECM is a more complex problem requiring specialized diagnostic tools and expertise. Incorrectly diagnosing and attempting to repair the PCM/ECM could cause further damage.
Remember safety first! Always disconnect the battery negative terminal before working on any electrical components in your vehicle.
