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Home >> Lexus >> 1998 >> SC 400 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing >> Ignition Checks >> Spark Test (Es300, GS300 & SC300)
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Spark Test (Es300, GS300 & SC300)

NOTE: On ES300, three ignition coils are used and are located on left valve cover.
CAUTION: To prevent fuel from being injected during cranking in the following procedure, crank engine for no more than 5-10 seconds at a time.
  1. Disconnect ignition coil connector. Disconnect injector connector for cylinder being tested. Remove ignition coil to be checked. Remove spark plug. Connect spark plug to coil and reconnect ignition coil connector. Ground the spark plug.
  2. Check plug for spark while cranking engine. If spark is not present, turn ignition off. Check ignition coil and ignitor connectors. Repair as necessary. If connections are good, using an ohmmeter, check resistance of secondary ignition wires. Resistance should be less than 25000 ohms.
  3. If resistance is not as specified, replace wires as necessary. If wires are good, turn ignition on. Using a voltmeter, check for battery voltage between ground and positive terminal (Black/Red wire on ES300 or Black/White wire on GS300 and SC300) at ignition coil and ignitor connectors.
  4. If battery voltage is not present, repair circuit between ignition switch and ignition coil or ignitor. If battery voltage is present, check resistance between terminals of ignition coil connector (ignition coil primary resistance). If resistance is not as specified, replace ignition coil. See IGNITION COIL RESISTANCE TABLE (ES300)  or IGNITION COIL RESISTANCE TABLE (GS300 & SC300) .
  5. If resistance is as specified, check resistance between terminals of Camshaft Position (CMP) sensor. See SENSOR RESISTANCE  table. If resistance is not as specified, replace CMP sensor. If resistance is as specified, check resistance between terminals of Crankshaft Position (CKP) sensor. See SENSOR RESISTANCE  table.
  6. If resistance is not as specified, replace CKP sensor. If resistance is as specified, check for ignitor circuit malfunction (IGT signal). If IGT signal from ECM is defective a Diagnostic Trouble Code (DTC) should set in ECM memory. See testing procedure for DTC P1300 in TESTS W/CODES article. If IGT signal circuit is okay, substitute another ignitor and recheck system operation.
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