1. Check the Fuses: Start with the easiest. Consult your owner's manual to locate the fuse(s) related to the ignition system (often labeled "IGN" or "Ignition"). Check for blown fuses – visually inspect for a broken filament. Replace any blown fuses. If the problem persists, the fuse may be blowing due to a short circuit, so proceed with caution.
2. Ignition Switch: A faulty ignition switch can prevent power from reaching various parts of the ignition system, including the coil. With the key in the "ON" position, check for power at the ignition switch's output wire(s) that lead to the coil. You'll need a multimeter to do this. If there's no power here, the switch is suspect.
3. Relay (Ignition Control Module/PCM): Many vehicles of this era use a relay to control power to the ignition coil. This relay is often controlled by the PCM (Powertrain Control Module) or an ignition control module.
* Locate the relay: Find the relay(s) in the under-hood fuse box or inside the car's fuse panel. Your owner's manual should have a diagram.
* Test the relay: You can usually test the relay by swapping it with a similar-looking relay of the same amperage (a non-critical circuit relay). If the problem moves, you've found the culprit. If not, test the relay directly using a multimeter according to its specifications.
* PCM/Ignition Control Module: If the relay checks out, the PCM or an ignition control module may be faulty, causing it to not energize the relay. This requires more advanced diagnostic tools.
4. Wiring Harness: Inspect the wiring harness running from the ignition switch, through any relays, and to the coil. Look for broken, frayed, or corroded wires. Pay close attention to the connections at each end. A visual inspection might not be enough; you might need to use a multimeter to check for continuity in the wires.
5. Coil itself: While less likely if you have *no* power reaching it, it's possible the coil itself is internally shorted, causing a blown fuse or preventing power from passing through. However, this is usually diagnosed *after* verifying power reaches the coil's input.
6. Crankshaft Position Sensor (CKP Sensor): Some vehicles use a CKP sensor to signal the PCM when to energize the coil. A faulty CKP sensor can prevent the ignition system from firing. This is more likely to result in intermittent problems or a no-start condition.
Tools you'll need:
* Owner's manual: Crucial for fuse locations, diagrams, and specifications.
* Multimeter: Essential for checking voltages, continuity, and relay operation.
* Test light: Can help visually verify power at various points in the circuit.
* Wire diagram: A wiring diagram specific to your 1992 Dodge Spirit 4-cylinder will be invaluable. You can often find these online through repair manual websites.
Important Safety Note: Always disconnect the negative battery terminal before working on the electrical system. Be aware that high voltages are present in the ignition system, even with the key off.
If you're not comfortable working with automotive electrical systems, it's best to take the vehicle to a qualified mechanic for diagnosis and repair. Troubleshooting electrical issues requires careful attention to detail and understanding of automotive electrical principles.
