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.
Fuel Injector Circuit
Wiring diagram:
Engine Electrical System Refer to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM .
- Check or repair only faulty parts.
- Use the check board when measuring the ECM terminal voltage and resistance. Refer to ENGINE (DIAGNOSTICS) (H4DO)>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE CHECK BOARD .
- CHECK OPERATION OF EACH FUEL INJECTOR
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While cranking the engine, check each fuel injector emits operating sound. Use a sound scope or attach a screwdriver to the injector to listen to sounds for this check.
Does the fuel injector emit operating sound?
Yes : Check the fuel pressure. Refer to MECHANICAL (H4DO)>FUEL PRESSURE .
No : Go to 2.
- CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR (OPEN)
.
- Turn the ignition switch to OFF.
- Disconnect the connector from ECM.
- Move the A/C compressor aside so that it does not interfere with the work. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL INJECTOR
.NOTE: This procedure is required to disconnect the fuel injector #2 connector.
- Disconnect the connector from fuel injector.
- Measure the resistance of harness between ECM and fuel injector connector.
Connector & terminal
#1 (E53) No. 96 - (E101) No. 1:
#1 (E53) No. 87 - (E101) No. 2:
#2 (E53) No. 95 - (E102) No. 1:
#2 (E53) No. 86 - (E102) No. 2:
#3 (E53) No. 93 - (E103) No. 1:
#3 (E53) No. 84 - (E103) No. 2:
#4 (E53) No. 94 - (E104) No. 1:
#4 (E53) No. 85 - (E104) No. 2:
Is the resistance less than 1 Ω?
Yes : Go to 3.
No : Repair the following item.
- Open circuit in harness between ECM and fuel injector connector
- Poor contact of coupling connector
- CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR (SHORT TO GROUND)
.
Measure the resistance between fuel injector connector and engine ground.
Connector & terminal
#1 (E101) No. 1 - Engine ground:
#1 (E101) No. 2 - Engine ground:
#2 (E102) No. 1 - Engine ground:
#2 (E102) No. 2 - Engine ground:
#3 (E103) No. 1 - Engine ground:
#3 (E103) No. 2 - Engine ground:
#4 (E104) No. 1 - Engine ground:
#4 (E104) No. 2 - Engine ground:
Is the resistance 1 MΩ or more?
Yes : Go to 4.
No : Repair the short circuit to ground in harness between ECM and fuel injector connector.
- CHECK EACH FUEL INJECTOR
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Check each fuel injector. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL INJECTOR .
Is the check result OK?
Yes : Repair the poor contact of ECM connector.
No : Replace the faulty fuel injector. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL INJECTOR .
NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Refer to ENGINE (Diagnostics) (H4DO)>Basic Diagnostic Procedure>PROCEDURE .
Use the Manual With the Right Hardware
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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.
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