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Spark Test

  1. Turn ignition off. Check ignition coil, ignitor and distributor connectors. Repair as necessary. If connectors are okay, go to next step.
  2. 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.
  3. 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.
  4. Turn ignition off. Using a DVOM, measure resistance of ignition coil (cold). Primary resistance is .41-.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 next step.
  5. Using an ohmmeter, measure resistance of No. 1 cam position sensor. See Fig 1. 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 1: Checking LS400 No. 1 Cam Position Sensor Resistance
    G90A18879Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  6. Using an ohmmeter, measure resistance of No. 2 cam position sensor. See Fig 2. 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 2: Checking LS400 No. 2 Cam Position Sensor Resistance
    G90D18880Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  7. Using an ohmmeter, measure resistance of engine speed sensor. See Fig 3. 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 3: Checking LS400 Engine Speed Sensor Resistance
    G90E18881Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  8. Perform CODE 14 and CODE 15 (step 5) diagnostic procedures for LS400. See TESTS W/CODES article. 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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