* Ignition Coil(s): The Lumina likely has multiple ignition coils (one per cylinder or a pair for several cylinders). A faulty coil won't send the high voltage needed to ignite the spark plug. This is a very common cause of misfires. Check for cracks, corrosion, or obvious damage. Testing with a multimeter is often necessary to confirm a bad coil.
* Ignition Control Module (ICM): This module controls the ignition coil(s). A failing ICM can prevent the coils from receiving the signal to fire. Testing is usually required to diagnose an ICM issue.
* Ignition Switch: The ignition switch might be faulty and not providing power to the rest of the ignition system.
* Cranking Sensor/Cam Position Sensor (CMP): These sensors tell the ICM when to fire the spark. A faulty sensor means the ICM doesn't know when to energize the coils.
* Distributor (if equipped): Some 1990 Luminas might still use a distributor. If so, problems within the distributor (rotor, cap, internal components) could interrupt the spark delivery. Look for cracks, burns, or corrosion on the cap and rotor.
* Worn or Corroded Wires: Check all the wires connecting the ignition components (coils, ICM, distributor if applicable, etc.) for damage, breaks, or corrosion. Loose connections can also disrupt the current flow.
* Ignition Coil Wiring: Faulty wiring specifically to the coils can lead to a no-spark condition.
* Computer (PCM/ECM): In rare cases, a faulty PCM/ECM could be sending incorrect signals to the ignition system. This is usually a last resort diagnosis.
* Fuses and Relays: Check the fuses and relays associated with the ignition system.
Troubleshooting Steps:
1. Visual Inspection: Start with a visual inspection of all components mentioned above. Look for obvious damage, corrosion, loose connections, or burnt wires.
2. Check for Spark: Use a spark tester or even a spare plug wired to a good ground to test for spark at the coil(s) output. This helps isolate if the problem is before or after the coil.
3. Testing with a Multimeter: You'll need a multimeter to test the components for continuity, voltage, and resistance to confirm whether they are functioning correctly. Consult a repair manual for specific testing procedures for your Lumina's year and engine.
4. Professional Diagnosis: If you're not comfortable working on your car's electrical system, take it to a mechanic for diagnosis and repair.
Ignoring the problem could lead to engine damage, so it's important to address this issue as soon as possible. A simple visual check and spark test might point you in the right direction, but more advanced testing is often required for a definitive diagnosis.
