Ignition System Checks
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
- Inspect the spark plugs for correct operation and good ignition system performance.
- Check the ignition coil boots for cracking, chafing, and loose connections.
- Observe the SPARK parameter on the scan tool at idle, while operating rear defogger, A/C system, or headlights. If scan tool display remains fixed at 10 degrees, check for a short to ground in the Diagnostic Request circuit from the Powertrain Control Module (PCM) connector C4 terminal No. 20 to the Data Link Connector (DLC).
- Check the Knock Sensor (KS) and sensor circuit shielding. A faulty knock sensor or signal interference could cause excessive retard of the ignition timing advance. Observe the SPARK parameter on a scan tool and compare with a known good vehicle. A typical value at 60 MPH (98 km/h) with all engine accessories off is 26-32 degrees.