How to Fix the Duramax LLY Injector Harness

by Baptist Johnson

The Duramax is a family of large diesel engines manufactured by General Motors. Like all engines, Duramax engines rely on a functioning fuel system to fire. The fuel injector is an essential component of the fuel system. It helps maintain the flow of fuel to the engine. A common issue with fuel injectors is the wiring harness has corroded, which can lead to a fuel leak. Check the fuel injector harness, which secures the fuel line to the fuel injector. When a fuel injector goes bad, you may notice some starting problems with your vehicle.


Park your vehicle in a safe location on level ground. Engage the parking brake and turn off the ignition. Open the hood.


Locate the fuse box in the hood area along the passenger’s side. Open the fuse box. Remove the fuel pump fuse from the fuse box to relieve the pressure in the fuel system. Disconnect the negative cable from the battery.


Locate the fuel injectors, which are mounted in the area where the engine block connects to the fuel line. Identify the fuel injectors as nipple-like valves that connect the fuel rail to the engine. Depending on the size of your Duramax engine, your vehicle may have several fuel injectors.


Inspect the wiring harness that surrounding the fuel injectors. Look for visible signs of corrosion, excessive dirt or damage. The wiring harness should also be intact with no cracks.


Select a wiring harness that appears damaged. Trace the fuel line away from the engine until you reach the fuel rail. Inspect the fuel rail for bracket which holds the fuel rail in place. Unbolt the bracket to release the fuel rail. You should now be able to slightly maneuver the fuel rail away from the engine.


Trace the fuel line back to the wiring harness. Disconnect the wiring harness from the fuel injector by pressing the center of the securing clip located at the tip of the wiring harness. With the wire clip pressed, slide the fuel line along with the wiring harness away from the fuel injector.


Inspect the wiring harness. Notice the clip that slides over the wiring harness. Depress this clip and remove the wiring harness from the fuel line. Replace the wiring harness with a new harness by sliding it onto the fuel line underneath the clip. You should hear an audible click with the clip secures the new harness.


Align the fuel line and the wiring harness with the fuel injector. Press the wiring harness into the fuel injector until the clip secures the fuel injector and the wiring harness. Secure the fuel rail back in place with its mounting bracket. Replace the fuel pump fuse in the fuse box. Connect the negative cable to the battery.

About the Author

Baptist Johnson was first published in 2000 when a poem he wrote won first prize in a local writing contest. He also writes and edits for Etched Press Society, a micro-publishing company based in Wilmington, N.C. Johnson has a Bachelor of Science in business administration from East Carolina University.

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