1. Ignition Switch:
* Check the ignition switch: This might seem obvious, but a faulty switch can prevent power from reaching the rest of the ignition system. Try wiggling the key while someone tries to crank the engine. A temporary spark might indicate a problem here. This is often overlooked.
* Power to the switch: Check for power at the ignition switch itself (with the key in the "ON" position). You'll need a test light or multimeter to do this. The wiring diagram is your friend here.
2. Ignition Control Module (ICM):
* Location: The ICM is a common failure point in these older cars. It's usually located near the distributor or the coil. Its location varies by model year; consult a wiring diagram.
* Testing: Testing the ICM requires a bit more knowledge and ideally an oscilloscope or a dedicated ICM tester. A multimeter can check for power and ground, but a true diagnosis often needs specialized equipment. Many auto parts stores can test them for you.
3. Pick-up Coil (Distributor):
* Location: This is inside the distributor. It senses the position of the rotor and sends that signal to the ICM.
* Testing: A multimeter can check for continuity and resistance within the pick-up coil itself. Again, the values you're looking for will be found in a service manual.
* Worn Distributor: Even if the pick-up coil tests okay, the distributor itself can wear, leading to poor signal quality or misalignment.
4. Crankshaft Position Sensor (CKP Sensor): (Depending on the exact engine)
* Location: Some engines may use a CKP sensor instead of relying solely on the distributor. This is more common in later models but might be present in your specific 1988 Delta 88.
* Testing: Similar to the pick-up coil, the CKP sensor requires testing for continuity and resistance. Its location and testing procedures are specified in the repair manual.
5. Wiring and Connectors:
* Inspect Wiring: Carefully inspect all wiring and connectors related to the ignition system. Look for any signs of corrosion, damage, or loose connections. Pay particular attention to the wiring leading to the ICM, distributor, and coil.
* Continuity Check: Use a multimeter to check for continuity in the wiring harness between various components.
6. Past Repairs:
* Consider past repairs or modifications. Did someone previously work on the ignition system? They may have inadvertently introduced a problem.
Important Considerations:
* Repair Manual: A factory service manual for your specific 1988 Oldsmobile Delta 88 is invaluable. It contains wiring diagrams, component specifications, and testing procedures. You can often find them online through various sources.
* Safety: Always disconnect the negative battery terminal before working on any electrical system.
* Professional Help: If you're not comfortable working with automotive electrical systems, it's best to seek help from a qualified mechanic. Improperly diagnosing and repairing an electrical problem can lead to further damage.
Start with the simpler checks (ignition switch, visual inspection of wiring) and progress to the more complex ones (ICM, sensors). Remember to consult your repair manual for specific testing procedures and component locations for your vehicle.
