1. Confirm No Spark: Double-check you actually have no spark. Use an inline spark tester (NOT a screwdriver!) on each spark plug wire to confirm. A weak spark might be missed visually.
2. Verify Injector Pulse: How are you verifying injector pulse? Using a noid light or a multimeter? A noid light will visually indicate pulse. A multimeter can confirm a voltage change (pulse) across the injector connector. Make sure your testing method is reliable.
3. Ignition Control Module (ICM): Since you have injector pulse but no spark, the ICM is a prime suspect. The ICM receives signals from the computer and controls the ignition coil. A faulty ICM will prevent spark even if the computer is sending signals to the injectors. This is often the culprit in this specific scenario.
4. Ignition Coil: While less likely given you have injector pulse (indicating a functioning computer and related circuits), a bad coil can still cause no spark. Check for continuity and resistance of the coil using a multimeter, according to the specifications in your repair manual.
5. Crank Sensor (or Cam Sensor - depending on engine): A faulty crank position sensor (or camshaft position sensor) won't allow the computer to trigger the ignition system. While you have injector pulse, a weak signal might be enough for fuel injection but insufficient for ignition. Test the sensor's output voltage while cranking.
6. Wiring: Inspect the wiring between the ICM, coil, crank sensor, and computer for any damage, corrosion, or loose connections. Focus on the high-voltage ignition wiring to the coil and distributor (if equipped).
7. Computer (PCM): The PCM is the least likely culprit given the injector pulse, but a malfunctioning computer can exhibit strange symptoms. This is a more advanced troubleshooting step requiring specialized tools and knowledge.
8. Distributor (if applicable): If your S10 has a distributor, check for issues inside, such as worn points (less likely on a '92), a bad rotor, or a faulty cap. Inspect for cracks or carbon tracking on the distributor cap and rotor.
Troubleshooting Steps in Order:
1. Visually inspect all components: Look for obvious damage to wires, connectors, or components.
2. Test the coil: Check for continuity and resistance with a multimeter.
3. Test the crank/cam sensor: Check for proper voltage output while cranking.
4. Replace the ICM: This is often the most likely solution given the symptoms. They are relatively inexpensive and easy to replace.
5. Check all wiring connections: Look for corrosion, loose connections, and broken wires.
Before you start:
* Consult a repair manual: A factory service manual for your specific year and engine is invaluable. It provides wiring diagrams, component specifications, and troubleshooting procedures.
* Safety First: Disconnect the negative battery terminal before working on any electrical components.
Remember, diagnosing electrical issues requires a systematic approach and often the use of a multimeter. If you are not comfortable working on car electrical systems, it's best to take your truck to a qualified mechanic.
