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Home >> Saab >> 1993 >> 900 Commemorative >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Ignition System >> Timing Control Systems >> Knock Sensor (Except 9000 Series Turbo)
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Knock Sensor (Except 9000 Series Turbo)

  1. Connect timing light. With engine running at a fast idle, tap cylinder head with a plastic mallet. If timing retards, knock sensor is okay. If timing does not retard, turn ignition switch off. Go to step 2) for 900 Series, or to step 4) for 9000 Series.
  2. On 900 Series, locate knock sensor under intake manifold. Unplug connectors from sensor and ignition ECM. Check Green wire for continuity between harness connector and ignition ECM pin No. 13. Also check Green wire for short to ground, to Brown wire, or to shield.
  3. Check Brown wire for continuity between harness connector and ignition ECM pin No. 12. Also check Brown wire for short to ground, to Green wire, or to shield. Ensure there is continuity between shield and ground. Replace wire assembly if defective. Go to step 6).
  4. On 9000 Series, locate knock sensor under intake manifold. Unplug connectors from sensor and ignition ECM. Check Gray wire for continuity between harness connector and ignition ECM pin No. 11. Also check Gray wire for short to shield or to ground.
  5. Check shield for continuity between sensor harness connector and ignition ECM pin No. 30. Check shield for short to ground. Replace wire if defective.
  6. Temporarily replace knock sensor with known good unit. Repeat step 1). If timing still does not retard, reinstall original sensor and replace ignition ECM.
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