Engine Controls - Basic Testing: Diagnosis Lexus LX J80

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and are not pinched or cut. See VACUUM DIAGRAMS article to verify routing and connections (if necessary). Inspect air induction system for possible vacuum leaks.

SPARK TEST

1. Disconnect high tension coil wire from distributor cap. Hold coil wire approximately 1/2" away from body or engine ground. CAUTION: To prevent gasoline from being injected, DO NOT crank engine for longer than 2 seconds.
2. Crank engine and check for spark. If spark does exist, check ignition coil, igniter and distributor electrical connections.
3. If electrical connections are okay, go to next step. If electrical connections are defective, repair as necessary and recheck for spark.
4. Using ohmmeter, check resistance of spark plug and ignition coil high tension wires. Resistance should be within specification. See «HIGH TENSION WIRE RESISTANCE SPECIFICATIONS»(ref-21926-S27114886672001010300000) table. If resistance is within specification, go to next step. If resistance is not within specification, replace high tension wire. HIGH TENSION WIRE RESISTANCE SPECIFICATIONS Application Maximum Ohms Land Cruiser, LX450 25,000 Per Wire
5. Turn ignition on. Check for battery voltage at igniter and ignition coil positive terminal. If battery voltage exists, go to next step. If battery voltage does not exist, check wiring between ignition switch, ignition coil and igniter. See appropriate wiring diagram in WIRING DIAGRAMS article.
6. Check ignition coil resistance. See «IGNITION COIL RESISTANCE»(ref-21926-S34973185402001010300000) under IGNITION CHECKS (DISTRIBUTOR TYPE IGNITION SYSTEM). If ignition coil resistance is within specification, go to next step. If ignition coil resistance is not within specification, replace ignition coil.
7. Check pick-up coil resistance. See «PICK-UP COIL RESISTANCE»(ref-21926-S27641032932001010300000) under IGNITION CHECKS (DISTRIBUTOR TYPE IGNITION SYSTEM). If pick-up coil resistance is within specification, go to next step. If pick-up coil resistance is not within specification, replace distributor assembly.
8. Check resistance of crankshaft position sensor. See «CRANKSHAFT POSITION SENSOR RESISTANCE»(ref-21926-S09581909582001010300000) under IGNITION CHECKS (DISTRIBUTOR TYPE IGNITION SYSTEM). If crankshaft position sensor resistance is within specification, go to next step. If crankshaft position sensor resistance is not within specification, replace crankshaft position sensor.
9. Check pick-up coil air gap. See «PICK-UP COIL AIR GAP»(ref-21926-S13029098552001010300000) under IGNITION CHECKS (DISTRIBUTOR TYPE IGNITION SYSTEM). If pick-up coil air gap is correct, go to next step. If pick-up coil air gap is incorrect, replace distributor assembly.
10. Check ignition IGT signal from Engine Control Module (ECM). If ignition IGT signal from ECM is defective, a diagnostic trouble code P1300 will be set in the ECM memory to indicate a igniter circuit malfunction. See TESTS W/CODES article for diagnostic trouble code.
11. If IGT signal is okay, substitute another igniter and recheck system operation. If IGT signal is defective, check wiring between Engine Control Module (ECM), distributor and igniter. If wiring is defective, repair wiring as necessary and recheck system operation. If wiring is okay, substitute another ECM and recheck system operation.