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Fuel Injector Circuit Check: Wiring Diagram: Troubleshooting

NOTE: The connectors of the ECM are watertight. If tester probes are directly connected to any of the connectors when checking the ECM and its circuits, the watertight performance of the connector will be affected, possibly resulting in corrosion of connector terminals and damage to electrical circuits. Always use the special tool when checking the circuits. Connect tester probes only to the special tool's connectors.
FUEL INJECTOR CIRCUIT TROUBLESHOOTING REFERENCE CHART

Step Action YES NO
1  Fuel injector check for operating sound 
  1. Using sound scope, check each injector for operating sound with engine cranking.

Do all injectors make operating sound? 		 Fuel injector circuit is in good condition. Go to Step 2.
2  Fuel injector resistance check 
  1. Turn OFF ignition switch and disconnect connector from fuel injectors.
  2. Check for proper connection to fuel injector at each terminals.
  3. If OK, check all fuel injectors for resistance. See Fuel Injector On-Vehicle Inspection 

Are all injectors in good condition? 		 Go to Step 3. Replace fuel injector. See Fuel Injector Removal and Installation 
3  Fuel injector insulation resistance check 
  1. Check that insulation resistance is infinity between each fuel injector terminal and engine ground.

Is it in good condition? 		 Go to Step 4. Replace fuel injector. See Fuel Injector Removal and Installation 
4  Fuel injector power supply circuit check 
  1. Check that voltage between each fuel injector power supply circuit (B1, B2, B3, B4) and engine ground is battery voltage with ignition switch in ON position.

Is it in good condition? 		 Go to Step 5. Repair or replace fuel injector power supply circuit.
5  Fuel injector drive circuit check 
  1. Turn OFF ignition switch and disconnect connectors from ECM.
  2. Check that fuel injector drive circuits (A1, A2, A3, A4) are as follows.
    • Wiring harness resistance of each fuel injector drive circuit is less than 3 Ω.
    • Insulation resistance between each fuel injector drive circuit and vehicle body ground is infinity.
    • Circuit voltage of each fuel injector drive circuit is 0 - 1 V with ignition switch in ON position.

Are they in good condition? 		 Go to Step 6. Repair or replace fuel injector drive circuit.
6  Fuel injector check 
  1. Check fuel injector. See Fuel Injector Inspection 

Is it in good condition? 		 Substitute a known-good ECM and recheck. Replace fuel injector. See Fuel Injector Removal and Installation 
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