This code isn't pinpointing a single faulty component. Instead, it suggests a problem within the ignition system's readiness procedures. Potential causes include:
* Poor Cranking: If the engine doesn't crank sufficiently, the ignition system might not have enough time to become ready. This could be due to a weak battery, faulty starter, or issues with the engine's mechanical components.
* Faulty Crankshaft Position Sensor (CKP): The CKP sensor is crucial for the ignition timing. A faulty sensor can prevent the ignition system from properly initializing.
* Faulty Cam Position Sensor (CMP): Similar to the CKP, a malfunctioning CMP sensor will disrupt ignition timing and readiness.
* Ignition Coil Problems: Though less likely to directly trigger this code, faulty ignition coils can lead to misfires that indirectly affect the readiness test.
* Wiring Issues: Damaged or loose wiring within the ignition system can also prevent proper communication and readiness.
* PCM Issues (Less Likely): While less common, a problem with the PCM itself could be the culprit. This is usually only diagnosed after other possibilities are eliminated.
Troubleshooting:
You should start by checking the obvious:
1. Battery Voltage: Ensure the battery is fully charged and capable of delivering sufficient cranking amps.
2. Starter Motor: Make sure the starter is functioning correctly and engaging properly.
3. Check for Error Codes: Beyond P1684, are there any other diagnostic trouble codes present? These could provide additional clues.
4. Inspect Wiring: Examine the wiring harness associated with the ignition system for any signs of damage, corrosion, or loose connections.
5. Inspect Sensors: Visually inspect the CKP and CMP sensors for any physical damage. A professional might need to test their functionality.
If you're not comfortable performing these checks, it's best to take the vehicle to a qualified mechanic for diagnosis and repair. Simply clearing the code without addressing the underlying issue will likely cause it to reappear.
