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Fuel Injector Circuit Diagnosis

  1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - PRIZM article. Repair any faults identified and go to next step.
    2. CAUTION: Ensure Malfunction Indicator Light (MIL) and Data Link Connector (DLC) function properly. See MIL INOPERATIVE, MIL ON STEADY and/or DATA LINK CONNECTOR DIAGNOSIS under CIRCUIT TESTS in SELF-DIAGNOSTICS - PRIZM article.
  2. Turn ignition off. Disconnect all 4 fuel injector electrical connectors. Install Injector Test Light (J-34730-2B) in each fuel injector harness connector. While cranking engine, observe injector test lights. If injector test lights do not flash for each injector while cranking engine, go to next step. If injector test light flash for each injector while cranking engine, check fuel injector coils. See SYSTEM & COMPONENT TESTING - CARS - PRIZM article.
  3. If fuel injector test light does not flash on at least one fuel injector, go to next step. If fuel injector test light flashed on at least one fuel injector circuit while cranking engine, go to step  5 .
  4. Check for an open in fuel injector positive voltage circuit (Black/White wire) between ignition switch, through junction block No. 2 to splice located at center rear of engine compartment. See WIRING DIAGRAMS article. After repair, go to step  12 .
  5. If any injector test light was illuminated all the time while cranking engine, go to next step. If no injector test light was illuminated all the time while cranking engine, go to step  8 .
  6. Turn ignition off. Leave fuel injector test light(s) installed in fuel injector harness connector that remained illuminated all the time while cranking engine. Disconnect PCM connector C1. See Figure and Figure . Turn ignition on (engine off). If fuel injector test light(s) illuminate, go to next step. If fuel injector test light(s) do not illuminate, go to step  11 .
  7. Locate and repair short to ground in faulty fuel injector control circuit (Yellow wire for injector No. 1; Black/Red wire for injector No. 2; White wire for injector No. 3; Black wire for injector No. 4) between fuel injector and PCM connector C1. See WIRING DIAGRAMS article. After repair, go to step  12 .
  8. Remove fuel injector test light(s) from fuel injector harness connector(s). Connect a test light between ground and ignition positive voltage side (Black/White wire at terminal No. 2) of fuel injector harness connector that did not flash. Turn ignition on (engine off). If test light does not illuminate, go to next step. If test light illuminates, go to step  10 .
  9. Repair open in fuel injector positive voltage circuit (Black/White wire) between fuel injector and splice located at center rear of engine compartment. See WIRING DIAGRAMS article and Figure and Figure . After repair, go to step  12 .
  10. Check for open in faulty fuel injector control circuit (Yellow wire for injector No. 1; Black/Red wire for injector No. 2; White wire for injector No. 3; Black wire for injector No. 4) between fuel injector and PCM connector C1. See WIRING DIAGRAMS article and Figure and Figure . Repair as necessary. Repeat steps  5 through  10 until fuel injector test light flashes for all 4 fuel injector circuits. If open circuit was not located and repaired, go to next step. If open circuit was located and repaired, go to step  12 .
  11. Replace PCM. After repair, reprogram PCM and go to next step. See PROGRAMMING in SELF-DIAGNOSTICS - PRIZM article.
  12. Using scan tool, clear all Diagnostic Trouble Codes (DTC). See CLEARING DIAGNOSTIC TROUBLE CODES in SELF-DIAGNOSTICS - PRIZM article. Turn ignition off for at least 30 seconds. Start engine. Operate vehicle under same conditions as recorded for original symptom. If system operates properly, go to next step. If system does not operate properly, check for presence of water contamination of fuel, faulty injector spray pattern, leaking or stuck closed fuel injector, incorrect amount of fuel delivered by fuel injector, and fuel injector resistance. If there is spark but no fuel injector pulse, check ground point at rear of cylinder head. See SYSTEM & COMPONENT TESTING - CARS - PRIZM article.
  13. Using a scan tool, observe stored information under CAPTURE INFO. If scan tool does not display any DTCs that have not been diagnosed, fuel injector circuit is operating properly. If scan tool displays any DTCs that have not been diagnosed, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - PRIZM article.
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