Fuel Injector Circuit Check: Troubleshooting

NOTE:

Before troubleshooting, be sure to read PRECAUTIONS FOR FUEL SYSTEM SERVICE .
When measuring circuit voltage and/or pulse signal at ECM connector, connect special tool to ECM and ECM connectors.

TROUBLESHOOTING CHART

Step	Action	YES	NO
1	Fuel injector check for operating sound Using sound scope, check each injector for operating sound with engine cranking. Do all injectors make operating sound?	Fuel injectors circuit is in good condition.	Go to Step 2.
2	Fuel injector resistance check Turn OFF ignition switch and disconnect connectors from fuel injectors. Check for proper connection to fuel injector at each terminals. 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.
3	Fuel injector insulation resistance check 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.
4	Fuel injector power supply circuit check 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. If it is in good condition, go to ECM POWER AND GROUND CIRCUIT CHECK .
5	Fuel injector drive circuit check Turn OFF ignition switch and disconnect connectors from ECM. 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 Check fuel injector. See FUEL INJECTOR INSPECTION . Is it in good condition?	Substitute a known-good ECM and recheck.	Replace fuel injector.