Check Fuel Injector Operation - Verify injector operation using a stethoscope or screwdriver to hear operating sounds while engine is cranked. If operating sounds are not heard, go to next step. If operating sounds are heard, verify fuel pressure. See FUEL PRESSURE under FUEL SYSTEM.
Check Fuel Injector Power Circuit - Turn ignition off and disconnect Gray 4-pin fuel injector harness connector. Turn ignition on. Measure voltage between injector harness male connector terminal No. 1 (White/Black wire) and ground. If more than 9 volts are present, go to next step. If more than 9 volts are not present, repair harness or connectors as necessary.
Check Fuel Injectors - Measure resistance between Gray 4-pin fuel injector harness connector terminal No. 1 (White/Black wire) and terminals No. 2 (White/Yellow wire), No. 3 (White/Brown wire) and No. 4 (White/Green wire). Verify 10-18 ohms resistance between terminal No. 1 and each specified terminal. If resistance is as specified, go to next step. If resistance is not as specified, go to step 6).
Measure Voltage Between ECU Connectors & Fuel Injectors - Connect Gray 4-pin fuel injector harness connector. Turn ignition on. Measure voltage between ECU connector terminals No. 11 (White wire), No. 12 (White/Yellow wire) and No. 25 (White/Green wire) and ground. Measured voltage between each terminal and ground should be more than 8 volts. If more than 8 volts are present, go to next step. If voltage is less than 8 volts, repair harness or connectors as necessary.
Check Resistance Between ECU & Ground - Disconnect ECU 26-pin connector. Measure resistance between connector terminal No. 13 (Black/Blue wire) and ground, and between terminal No. 26 (Black/Blue wire) and ground. If resistance is more than 10 ohms, repair harness or connectors between ECU and fuel injectors, as necessary. If resistance is less than 10 ohms, inspect ECU terminal contact. Repair harness or connectors as necessary. If harness and connectors are okay, replace ECU.
Check Fuel Injection Engine Harness - Turn ignition off. Remove throttle body from intake manifold. Disconnect each injector 2-pin connector. Disconnect Gray 4-pin fuel injector harness connector. Verify infinity resistance between terminals No. 1 and No. 2 of each injector connector. Verify infinity resistance between terminals No. 2 (White/Yellow wire) and No. 3 (White/Brown wire), No. 2 (White/Yellow wire) and No. 4 (White/Green wire), and No. 3 (White/Brown wire) and 4 (White/Green wire) of 4-pin harness connector. Measure resistance between 4-pin connector and each injector 2-pin connector. See FUEL INJECTION ENGINE HARNESS RESISTANCE TESTING table. If resistance between harness terminals is not as specified, replace fuel injection engine harness. If resistance between harness connector terminals is as specified, replace malfunctioning fuel injector(s).

FUEL INJECTION ENGINE HARNESS RESISTANCE TESTING ⁽¹⁾

Gray 4-Pin Terminal No.

Cylinder No.

Injector 2-Pin Term. No.

2 (WHT/YEL Wire)

3 (WHT/BRN Wire)

4 (WHT/GRN Wire)

1 (WHT/BLK Wire)

⁽¹⁾	Resistance between 4-pin harness connector and injector 2-pin connector terminals is less than one ohm.

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.

Safety Warning

Fuel Injector Circuit Tests: JUSTY

Use the Manual With the Right Hardware

When to See a Mechanic

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