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 Circuits (G20)
- With engine idling, listen to each injector for operating sound. Each injector should click. If each injector clicks, test is complete. If any injector does not click, go to next step.
- Turn ignition off. Disconnect inoperative injector harness connectors. Turn ignition on. Measure voltage between ground and injector harness connector terminal No. 1 (Black/Red wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short circuit and retest system. See appropriate wiring diagram in WIRING DIAGRAMS article.
- Turn ignition off. Disconnect ECM harness connector. See Figure. Check continuity of the following:
- Red/Black wire between injector No. 1 harness connector terminal No. 2 and ECM harness connector terminal No. 101.
- Yellow/Black wire between injector No. 2 harness connector terminal No. 2 and ECM harness connector terminal No. 103.
- Green/Black wire between injector No. 3 harness connector terminal No. 2 and ECM harness connector terminal No. 105.
- Blue/Black wire between injector No. 4 harness connector terminal No. 2 and ECM harness connector terminal No. 107.
See Figure. Also check circuit for short to ground and short to voltage. Repair as necessary and retest system. If circuit is okay, go to next step.
- Check fuel injector. See FUEL INJECTOR . Replace, if necessary and retest system. If fuel injector is okay, go to next step.
- No problem is indicated at this time. Problem may be intermittent. See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION article.
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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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