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Home >> Buick >> 1996 >> Roadmaster Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1222 - Injector Control Circuit Intermittent >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Start and idle engine. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P0200. If scan tool indicates that DTC P0200 failed this ignition, diagnose affected DTC. If scan tool does not indicate that DTC P0200 failed this ignition, go to next step.
  3. Using scan tool, select MISFIRE DATA LIST and monitor MISFIRE HIST. COUNTERS. If counter indicates a number other than 0.0 counts, go to step 5). If counter does not indicate 0.0 counts, go to next step.
  4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within the conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P1222. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  5. Using scan tool, select MISFIRE DATA LIST and monitor MISFIRE HIST. COUNTERS for the affected cylinder, while moving related harness connectors (at injector and PCM). If counter value starts incrementing, go to next step. If counter value does not change, diagnose fuel injector. See SYSTEM/COMPONENT TESTS article.
  6. Turn ignition off. Disconnect harness connector to affected injectors. Turn ignition on. Using a test light connected to ground, probe injector harness connector ignition feed circuit. If test light illuminates, go to step 9). If test light does not illuminate, go to next step.
  7. Turn ignition off. Disconnect PCM harness connector C1. Using a jumper, ground injector control circuit for affected cylinder at PCM harness connector. Connect test light to battery positive. Probe injector feed circuits of one of the disconnected injector harnesses. If test light illuminates, go to next step. If test light did not illuminate, go to step 10).
  8. Repair injector driver circuit to affected injector. After repairs, go to step 11).
  9. Repair injector driver feed circuit. After repairs, go to step 11).
  10. Reinspect all related circuit and connections. Repair as necessary. After repairs, go to next step. If circuits and connections are okay, diagnose fuel injection. See SYSTEM/COMPONENT TESTS article.
  11. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1222. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool did not indicate that this test ran and passed, repeat step 2).
  12. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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