1. Ignition Coil: This is a common culprit. Locate the coil; it's usually near the distributor (if it has one - see point 2) or sometimes mounted directly on the distributor cap. Visually inspect it for cracks or damage. You'll need a multimeter to test the coil's primary and secondary resistances. Refer to your Buick Century's repair manual for the correct resistance values. A bad coil will show incorrect readings.
2. Distributor (if equipped): The 1989 Buick Century *may* have a distributor, or it might use a different ignition system (like a coil-near-plug setup). If it *has* a distributor:
* Rotor: Check for cracks or carbon buildup on the rotor.
* Distributor Cap: Look for cracks, corrosion, or burned areas inside the cap. Check for good contact between the rotor and cap terminals.
* Pick-up Coil (or Ignition Module inside the distributor): This is more complex to test and often requires a specific tool or an oscilloscope. A faulty pick-up coil (or module) prevents the distributor from sending the signal to the coil. Again, consult your repair manual.
3. Ignition Control Module (ICM): This module is the "brain" of the ignition system in many vehicles. It's separate from the distributor (if there is one) and often located near the firewall or under the dash. Testing this component usually requires a multimeter and knowledge of its specific operation. A faulty ICM is a common cause of no spark.
4. Cranking System: Does the engine crank over when you turn the key? If not, you have no spark because there's no power going anywhere. Check the battery, cables, starter motor, and related connections.
5. Ignition Switch: A faulty ignition switch might not be sending power to the ignition system. This is less common but possible.
6. Fuses and Relays: Check the fuses and relays related to the ignition system. Your owner's manual or a repair manual will show the fuse box layout and indicate which fuses are relevant.
7. Wiring: Visually inspect all the ignition system wiring for any obvious damage (broken wires, loose connections, chafing against metal). Look for corroded terminals.
Important Considerations:
* Repair Manual: A repair manual specific to your 1989 Buick Century is invaluable. It provides wiring diagrams, component locations, testing procedures, and specifications.
* Safety: Disconnect the negative (-) battery cable before starting any electrical work to avoid accidental shocks.
* Professional Help: If you're not comfortable working on automotive electrical systems, take your car to a qualified mechanic. Improper diagnosis or repair can cause further damage.
Start with the simpler checks (visual inspection of the coil, distributor cap, and rotor) and gradually move to more complex tests. Remember to consult your repair manual for specific details and testing procedures.
