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Home >> Saturn >> 2002 >> SC2 Automatic, MP6 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0340: CMP Sensor Circuit >> Diagnostic Procedures
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Diagnostic Procedures

  1. Turn ignition off for 10 seconds. Start and operate engine at idle for 2 minutes. Using scan tool, monitor DTC LAST TEST. If LAST TEST failed, go to next step. If LAST TEST did not fail, problem is intermittent. See DIAGNOSTIC AIDS  .
  2. Using scan tool, monitor MISFIRE CURRENT CYL. #1 and 4 counters. If cylinder No. 1 and/or 4 misfire counter is filling up, diagnose using DTC P0300. See DTC P0300: ENGINE MISFIRE DETECTED  . If cylinder No. 1 and/or 4 misfire counter is not filling up, go to next step.
  3. Turn ignition off. Disconnect EI module harness connector. Turn ignition on, with engine off. Using DVOM, check voltage on EI module harness connector terminal "D" (Brown/White wire). If voltage reading is 4-6 volts, go to step  5 . If voltage reading is greater than 6 volts, repair short to voltage in circuit. If voltage reading is less than 4 volts, go to next step.
  4. Turn ignition off. Disconnect PCM harness connector J1. Check continuity between ground and EI module harness connector terminal "D" (Brown/White wire). If continuity exists, repair grounded circuit. If continuity does not exist, repair open in circuit, loose connections at PCM or faulty PCM.
  5. Using scan tool, monitor CMP RESYNC COUNTER while cranking engine for 5 seconds and momentarily jumpering EI harness connector terminal "D" (Brown/White wire) to ground. If counter increments up then resets to zero when circuit is jumpered to ground, go to next step. If counter does not increment up then reset to zero when circuit is jumpered to ground, replace PCM.
  6. High resistance exists in cylinder No. 1 secondary ignition system, or low resistance exists in cylinder No. 4 secondary ignition system. Check secondary ignition for arcing spark plug wire, corroded or loose spark plug terminals, spark plug wire resistance (1500-15,000 ohms), or faulty spark plug or gap for cylinders No. 1 and 4. Check for loose connections at EI module connector. Repair as necessary. If no problem is found, replace EI module.
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