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Home >> Mitsubishi >> 1993 >> Eclipse Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Tests >> Code 31: Knock Sensor
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Code 31: Knock Sensor

NOTE: For component terminal identification, see TERMINAL IDENTIFICATION  . For wiring diagrams, see WIRING DIAGRAMS article in this section.
  1. Manufacturer does not provide component testing procedure using scan tester. On Eclipse 2.0L turbo, manufacturer provides testing procedure using engine analyzer with oscilloscope capability. Refer to manufacturer's operation manual for instructions in use of oscilloscope. Go to next step.
  2. Connect oscilloscope special patterns pickup between ECM and ECM connector at ECM terminal No. 9. Start engine. Accelerate engine to 5000 RPM. Compare oscilloscope wave pattern with known-good wave pattern. See Fig 1 . If wave pattern is abnormal, replace knock sensor. If wave pattern is normal, go to next step.
    Fig 1: Known-Good Knock Sensor Wave Pattern ID
    G93E80279Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  3. Using DVOM, check voltage between chassis ground and knock sensor connector terminal No. 1. If voltage is not 8.0-11.0 volts, repair wiring harness as necessary. If voltage is as specified, go to step 5.
  4. Disconnect knock sensor connector and ECM connector. Ground ECM connector terminal No. 58. Using DVOM, check continuity between chassis ground and knock sensor connector terminal No. 1. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
  5. With knock sensor connector disconnected, check for continuity between chassis ground and knock sensor connector terminal No. 2. If continuity does not exist, repair wiring harness as necessary. If continuity exists, condition required to set code is not present at this time. Test is complete.