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Knock Sensor Circuit (Models Using Knock Sensor With Internal Spark Controller Module)

  1. An open or short circuit on knock sensor wire to PCM/VCM will set a related DTC. A false detonation signal will not cause PCM/VCM to set a DTC.
  2. Install scan tool. Using a metal object, tap on engine next to knock sensor and note knock parameter. Knock should be indicated on scan tool.
  3. If a scan tool is not available, connect tachometer to engine. Start engine and hold RPM above idle. Using a metal object, tap on engine close to knock sensor. A noticeable decrease in engine RPM should occur. If no RPM decrease occurred, check knock sensor-to-PCM/VCM circuit.
  4. On vehicles equipped with automatic transmission, it may be necessary to place transmission in Drive for timing change to occur.
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