System Diagnosis - Ignition System

Ignition System Circuit Schematic:

ELECTRONIC IGNITION SYSTEM DIAGNOSTICS
Before attempting to diagnose the ignition system, a diagnostic circuit check should be performed.

Verify no diagnostic trouble codes or information flags are stored in malfunction history and that the diagnostic system is functioning properly.

Verify customer complaint and use the symptom or the Complaint/Condition matrix chart that applies.

Perform a visual inspection of:
^ PCM grounds for being clean and tight.
^ Wiring for proper connections, pinches and cuts. Also check for proper routing of wires.
^ Vacuum hoses for splits, kinks and proper connections and routing. If no spark is present at any wire, refer to Chart 1. No Spark at Any Wire - Chart I



EI MODULE SPARK QUICK TEST:
Remove all four plug wires at the coil towers.

Have an assistant crank the engine. You should see sparks appear alternately between each pair of coil towers during cranking.

NOTE: Make sure all engine wiring is clear of the El module during this test or arcing interference may occur.

The EI module, crankshaft position sensor and the coil packs are good if sparks appear between the coil towers.

WARNING: The EI System can produce extremely high voltages. do not attempt to service this system while the engine is running or is being cranked.

^ The measured resistance from tower to tower on the coils should be 7-10k ohms.
^ The measured resistance of the crankshaft position sensor should be 700-900 ohms.
^ To test for spark at spark plug wires use Saturn service tool SA9199Z, ST-125 or equivalent.
^ Engine firing order 1-3-4-2.
^ Reversed crankshaft position sensor wires will result in a no start condition.