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Home >> Lexus >> 2000 >> SC 300 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1300: IGNITOR Circuit Malfunction >> Diagnosis & Repair
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Diagnosis & Repair

  1. Check for spark at misfiring cylinder. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article. If spark is present, go to next step. If spark is not present, go to step  4.
  2. Check for open or short in IGF circuit (Red/Yellow wire) between terminal No. 25 at ECM E15 connector and ignitor. Ignitor is located on left side of engine compartment, near shock tower. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, go to next step.
  3. Disconnect ignitor Black 10-pin connector. Access ECM under front of carpet on passenger side of vehicle. Turn ignition on. Backprobing, measure voltage between ground and terminal No. 25 (Red/Yellow wire) at ECM E15 connector. See Figure. If voltage is 4.5-5.5 volts, replace ignitor. If voltage is not 4.5-5.5 volts, replace ECM and retest.
  4. Check for open or short in IGT circuits (White/Green, Yellow and Green/White wires) between ECM E15 connector and ignitor. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If circuits are okay, go to next step.
  5. Access ECM under front of carpet on passenger side of vehicle. Backprobing, measure voltage between ground and terminal No. 11 (White/Green wire), No. 12 (Yellow wire) and No. 13 (Green/White wire) at ECM E15 connector while cranking engine. If voltage is .1-4.5 volts, go to next step. If voltage is not .1-4.5 volts, replace ECM and retest.
  6. Disconnect ignitor Black 10-pin connector. Backprobing, measure voltage between ground and terminal No. 11 (White/Green wire), No. 12 (Yellow wire) or No. 13 (Green/White wire) at ECM E15 connector while cranking engine. If voltage is .1-4.5 volts, go to next step. If voltage is not .1-4.5 volts, replace ECM and retest.
  7. Turn ignition switch to ON position and then to START position. Measure voltage between ground and terminal No. 9 (Black/White wire) at ignitor wiring harness connector. If voltage is not 9-14 volts, repair ignitor power source circuit. If voltage is 9-14 volts, go to next step.
  8. Check for open or short in wiring harness between ignition switch and ignition coil, and between ignition coil and ignitor. See WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, go to next step.
  9. Check ignition coils. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article. Replace ignition coils as necessary. If ignition coils are okay, check ignitor ground circuit (White/Red wire). Repair wiring as necessary. If ground circuit is okay, replace ignitor.
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