1. Ignition Control Module (ICM): This is a common culprit in older vehicles. The ICM sends the signal to the ignition coil, so a faulty ICM will prevent spark. This is a particularly likely suspect on a Reatta due to its age and the complexity of the system.
2. Ignition Coil: This component transforms low voltage from the ICM into the high voltage needed for spark. A failing coil will either produce weak spark (misfires) or no spark at all.
3. Crankshaft Position Sensor (CKP): The CKP sensor tells the computer the engine's rotational position. Without this information, the computer won't send the signal to fire the coil. A faulty CKP prevents the ignition system from functioning.
4. Cam Position Sensor (CMP): Similar to the CKP, but monitors the camshaft position. Some engine management systems rely on both CKP and CMP signals. A faulty CMP will also prevent spark.
5. Distributor (if applicable): While the Reatta's electronic ignition system is generally distributorless, a potential issue *could* still involve the ignition module inside the distributor if there’s some unusual variant or aftermarket modification. However, this is less likely than the other options.
6. Ignition Switch: A faulty ignition switch might not be sending power to the ignition system correctly.
7. Wiring and Connectors: Corrosion, broken wires, or loose connections anywhere in the ignition system can interrupt the electrical signal. Inspect all wiring harnesses, connectors, and grounds.
8. PCM (Powertrain Control Module): The computer itself could be faulty, though this is less common than the other components. A faulty PCM might not be sending the correct signals to the ICM.
9. Security System (if equipped): If the vehicle has a factory or aftermarket anti-theft system, a problem with it could prevent the engine from starting.
Troubleshooting Steps:
1. Check for power at the coil: With the key on, check if power is reaching the coil. This helps narrow down the problem to before or after the coil.
2. Check for power at the ICM: Similar to above, verifying power to the ICM is crucial.
3. Inspect fuses and relays: Ensure all relevant fuses and relays are intact and not blown.
4. Test the CKP and CMP sensors (if equipped): These sensors can be tested with a multimeter or an OBDII scanner (if compatible).
5. Visual inspection: Check for obvious signs of damage to the wiring, connectors, and components.
6. Professional Diagnosis: If you're not comfortable working with automotive electrical systems, a qualified mechanic with a diagnostic scanner can pinpoint the exact cause of the no-spark condition more efficiently. A scanner can read trouble codes from the PCM that could provide invaluable clues.
Without more information or diagnostic testing, pinpointing the exact cause is impossible. The steps above will help you systematically narrow down the possibilities. Remember safety first – disconnect the battery negative terminal before working on any electrical components.
