Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSLEXUS2004IS 300 BASE, AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCEIGNITION SYSTEMIGNITIONIGNITION SYSTEMON-VEHICLE INSPECTION

2004 Lexus IS 300 Base, Automatic

On-Vehicle Inspection

2004 Lexus IS 300 Base, AutomaticSECTION On-Vehicle Inspection

NOTE: "Cold" and "Hot" in these sentences express the temperature of the coils themselves. "Cold" is from -10°C (14°F) to 50°C (122°F) and "Hot" is from 50°C (122°F) to 100°C (212°F).

INSPECT IGNITER AND SPARK TEST
Check that the spark occurs.
1. Remove the ignition coil (See REMOVAL ).
2. Using a 16 mm plug wrench, remove the spark plug.
3. Install the spark plug to the ignition coil, and connect the ignition coil connector.
4. Ground the spark plug.
5. Check if spark occurs while engine is being cranked.
  NOTE: To prevent excess fuel being injected from the injectors during this test, do not crank the engine for more 5 - 10 seconds at a time.
  
  If the spark does not occur, do the test as follows:
  
  Fig 1: Spark Test Flow Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
6. Using a 16 mm plug wrench, reinstall the spark plug.
  1. Torque: 18 N.m (180 kgf.cm, 13 ft.lbf)
7. Reinstall the ignition coil (See INSTALLATION ).
INSPECT HIGH-TENSION CORDS
1. Remove the No.3 timing belt cover.
2. Remove the throttle body gasket (See REMOVAL ).
3. Disconnect the high-tension cord set from the spark plugs.
  
  Fig 2: Disconnecting High-Tension Cord
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Disconnect the high-tension cords at the rubber boot.
  
  DO NOT pull on the cords.
  
  NOTE: Pulling on or bending the cords may damage the conductor inside.
4. Disconnect the high-tension cord set from the ignition coils.
  1. Using a screwdriver, lift up the lock claw and disconnect the holder from the ignition coils.
    
    Fig 3: Lifting Lock Claw And Disconnecting Holder
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. Disconnect the high-tension cord at the grommet.
    DO NOT pull on the cord.
  NOTE:
  - Pulling on or bending the cords may damage the conductor inside.
  - Do not wipe any of the oil from the grommet after the high-tension cord is disconnected.
5. Using an ohmmeter, measure the resistance.
  1. Maximum resistance: 25 kΩ per cord
  If the resistance is greater than the maximum, check the terminals. If necessary, replace the high-tension cord.
  
  Fig 4: Measuring Resistance Using Ohmmeter
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
6. Reconnect the high-tension cord set to the ignition coils.
  1. Assemble the holder and grommet.
  2. Align the spline of the ignition coil with the spline of the holder, and push in the cord.
    
    Fig 5: Aligning Spline And Pushing In Cord
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.