With engine running, listen for clicking sound at each injector. If clicking sound is present at each injector, system is functioning properly. If clicking sound is not present, go to next step.
Turn ignition off. Disconnect injector harness connector(s). Turn ignition on. Measure voltage between ground and injector harness connector Black/Red wire(s). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check fusible link, ignition switch, and open or short in Black/Red wire between ignition switch and injector(s). Repair or replace as necessary. See WIRING DIAGRAMS article.
Turn ignition off. Disconnect PCM harness connector. Check continuity between specified PCM harness connector terminal and appropriate injector harness connector terminal. See INJECTOR CIRCUIT IDENTIFICATION (ALTIMA) table. If continuity exists in each circuit, go to next step. If continuity does not exist in any circuit, repair open or short in appropriate wire between PCM and injector harness connectors.
Check fuel injector(s). See FUEL INJECTOR . If fuel injectors are okay, check PCM harness connector terminals for damage or corrosion. Repair or replace as necessary.

INJECTOR CIRCUIT IDENTIFICATION (ALTIMA)

Application

PCM Terminal No. ⁽¹⁾

Wire Color

Injector No. 1

102

Red/Black

Injector No. 2

107

Yellow/Black

Injector No. 3

104

Green/Black

Injector No. 4

109

Blue/Black

⁽¹⁾	PCM harness connector terminal number. See Figure.

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 Test: Altima