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Spark Test

  1. On all models, check for spark. Remove coil wire from distributor. Using insulated pliers, hold end of coil wire 1/2" from ground. Crank engine. If spark is present, see ES250 DIAGNOSIS BY SYMPTOM or LS400 DIAGNOSIS BY SYMPTOM in TESTS W/O CODES article in the ENGINE PERFORMANCE Section. If spark is not present, go on to step 2).
  2. Turn ignition off. Check ignition coil, ignitor and distributor connectors. Repair as necessary. If connectors are okay, go to next step.
  3. Using an ohmmeter, check resistance of high tension cables. Maximum resistance allowed 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 has 2 ignition coils.
  5. Turn ignition off. Using a DVOM, measure resistance of ignition coil (cold). Primary resistance is .40-.50 ohm. Positive terminal on ignition coil has a tab next to terminal. Secondary resistance is 10,200-13,800 ohms. If resistance is not within specification, replace ignition coil. If resistance is within specification, go to step 6) for ES250 or step 9) for LS400.
  6. On ES250, measure resistance of pick-up coil. See Fig 1. Measure resistance between terminals G1 and G, G2 and G, and NE and G. Resistance should be 205-255 ohms. If resistance is not within specification, replace distributor housing assembly.
    Fig 1: Identifying Pick-Up Coil Connectors (ES250)
    G90I18877Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  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 is .008-.016" (.20-.40 mm). If air gap is not to specification, replace distributor.
    Fig 2: Measuring Pick-Up Air Gap (ES250)
    G90J18878Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  8. Perform CODE 14 (step 9) trouble shooting procedures for ES250. See TESTS W/CODES article in the ENGINE PERFORMANCE Section. If voltage reading and wiring harness are okay, try another ignitor.
  9. On LS400 models, using an ohmmeter, measure resistance of No. 1 cam position sensor. See Fig 3. Resistance specification is 950-1250 ohms. If No. 1 cam position sensor resistance is not to specification, replace sensor. If resistance is within specification, go to next step.
    Fig 3: Checking No. 1 Cam Position Sensor Resistance (LS400)
    G90A18879Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  10. Using an ohmmeter, measure resistance of No. 2 cam position sensor. See Fig 4. Resistance specification is 950-1250 ohms. If No. 2 cam position sensor resistance is not to specification, replace sensor. If resistance is within specification, go to next step.
    Fig 4: Checking No. 2 Cam Position Sensor Resistance (LS400)
    G90D18880Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  11. Using an ohmmeter, measure resistance of engine speed sensor. See Fig 5. Resistance specification is 950-1250 ohms. If engine speed sensor resistance is not to specification, replace sensor. If resistance is within specification, go to next step.
    Fig 5: Checking Engine Speed Sensor Resistance (LS400)
    G90E18881Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  12. Perform CODE 14 and CODE 15 (step 5) diagnostic procedures for LS400. See TESTS W/CODES article in the ENGINE PERFORMANCE Section. Reading should be approximately battery voltage.
  13. If voltage reading is okay, try another ignitor. If voltage reading is not within specification in CODE 14 and CODE 15 (step 5), continue with diagnostic procedures for CODE 14 and CODE 15.
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