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Home >> Lexus >> 1996 >> SC 300 Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> DTC P1300 - IGNITOR Circuit Malfunction >> Diagnosis & Repair

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 between ECM and ignitor. Ignitor is located on right side of engine compartment, near ignition coil. See appropriate wiring diagram in WIRING DIAGRAMS. Repair as necessary. If circuit is okay, go to next step.
  3. Disconnect 5-pin ignitor connector. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Measure voltage between ground and terminal No. 58 (Red/Yellow wire) at ECM "B" 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 circuit (White/Green wire) between ECM and ignitor. See appropriate wiring diagram in WIRING DIAGRAMS. Repair as necessary. If circuit is okay, go to next step.
  5. Measure voltage between ground and terminal No. 57 (White/Green wire) at ECM "B" 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 5-pin ignitor connector. Measure voltage between ground and terminal No. 57 (White/Green wire) at ECM "B" 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 on. Measure voltage between ground and terminal No. 3 (Black/Orange wire) at ignitor wiring harness connector. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, check and repair ignitor power source circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
  8. Check for an open or short in wiring harness between ignition switch and ignition coil, and between ignition coil and ignitor. Repair as necessary. If wiring is okay, go to next step.
  9. Check ignition coil. See IGNITION SYSTEM in SYSTEM & COMPONENT TESTING article. Replace coil as necessary. If coil is okay, replace ignitor.
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