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Spark Test

  1. Remove coil wire from distributor. Using insulated pliers, hold end of coil wire 1/2" from ground. Crank engine. If spark is present, see appropriate DIAGNOSIS BY SYMPTOM in TESTS W/O CODES article in the ENGINE PERFORMANCE Section.
  2. If spark is not present, turn ignition off. Check ignition coil, ignitor and distributor connectors. Repair as necessary.
  3. If connectors are okay, check resistance of high tension cables. Maximum resistance is 25,000 ohms per cable. Replace as necessary. If resistance is within specification, go to next step.
  4. Turn ignition on. Using a DVOM, ensure battery voltage is present at ignition coil positive terminal. If battery voltage is not present, check wiring between ignition switch and ignition coil. If battery voltage is present, go to next step.
    NOTE: LS400 and SC400 have 2 ignition coils.
  5. Turn ignition off. Using a DVOM, measure resistance of ignition coil (cold). Positive terminal on ignition coil has a tab next to terminal. See IGNITION COIL RESISTANCE table. If resistance is not within specification, replace ignition coil. If resistance is within specification, go to step 6) for ES300 and SC300 or step 9) for LS400 and SC400.
    IGNITION COIL RESISTANCE

    Application Primary Secondary
    ES300 .30-.60 9000-15,000
    LS400 & SC400 .40-.50 10,200-13,800
    SC300 .20-.30 6000-11,000
  6. On ES300 and SC300, measure resistance of pick-up coil. See Fig 1. See DISTRIBUTOR SENSOR RESISTANCE table. If resistance is not within specification, replace distributor housing assembly.
  7. Check air gap in distributor. Measure air gap of G1 pick-up, G2 pick-up and NE pick-up. See Fig 2. Air gap specification for ES300 is .008-.020" (.2-.5 mm). Air gap specification for SC300 is .008-.016" (.2-.4 mm). If air gap is not to specification, replace distributor.
  8. If air gap is to specification, perform appropriate trouble shooting procedures in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If voltage reading and wiring harness are okay, substitute ignitor with a known good unit.
    DISTRIBUTOR SENSOR RESISTANCE

    Application Ohms
    ES300 & SC300
    Pick-Up Coils
    Between Terminals G1 & G 125-190
    Between Terminals G2 & G 125-190
    Between Terminals NE & G 155-240
    LS400
    No. 1 & No. 2 Cam Sensors 950-1250
    Engine Speed Sensor 950-1250
    SC400
    No. 1 & No. 2 Cam Sensors 835-1350
    Engine Speed Sensor 835-1350
    Fig 1: Identifying Pick-Up Coil Connectors (ES300 & SC300)
    G92D26123Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    Fig 2: Measuring Pick-Up Air Gap (ES300 & SC300)
    G92E26124Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  9. On LS400 and SC400 models, use an ohmmeter to measure resistance of No. 1 cam position sensor. See Fig 3. See DISTRIBUTOR SENSOR RESISTANCE table. If No. 1 cam position sensor resistance is not to specification, replace sensor. If resistance is within specification, go to next step.
  10. Using an ohmmeter, measure resistance of No. 2 cam position sensor. See Fig 4. See DISTRIBUTOR SENSOR RESISTANCE table. If No. 2 cam position sensor resistance is not to specification, replace sensor. If resistance is within specification, go to next step.
  11. Using an ohmmeter, measure resistance of engine speed sensor. See Fig 5. See DISTRIBUTOR SENSOR RESISTANCE table. If engine speed sensor resistance is not to specification, replace sensor. If resistance is within specification, perform appropriate diagnostic procedures for LS400 or SC400. See TESTS W/CODES article in the ENGINE PERFORMANCE Section.
Fig 3: No. 1 Cam Position Sensor Resistance (LS400; SC400 Similar)
G90A18879Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 4: No. 2 Cam Position Sensor Resistance (LS400; SC400 Similar)
G90D18880Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 5: Engine Speed Sensor Resistance (LS400; SC400 Similar)
G90E18881Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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