BTR Fuel Injector Inner Harness and Plug Kit for Dodge (2003-05) 5.9L Cummins (Full Set)

The BTR IHK-3966805 Fuel Injector Inner Harness and Plug Kit is a complete three-piece replacement set for 2003–2005 Dodge 5.9L Cummins trucks. Located inside the rocker box below the valve cover, these harnesses provide the electrical connection between the engine wiring system and the fuel injectors. One harness serves two injectors, and three harnesses are required to service the full six-cylinder engine.

This full set is designed around the common Cummins 3966805 and Mopar 5139865AA reference numbers. Replacing all three inner injector harnesses at once is a practical option when the existing connectors show age, heat damage, brittle insulation, broken locking features, contamination, or intermittent electrical connection concerns.

Injector harness condition matters on the 5.9L Cummins because these connectors operate in a demanding under-valve-cover environment exposed to heat, vibration, and engine-oil contact. A compromised connection can create injector circuit issues that may present as rough running, misfire-like symptoms, inconsistent engine operation, or diagnostic trouble codes. This kit provides the complete set needed to address the engine rather than replacing only one section at a time.

The BTR IHK-3966805 is a strong service-minded replacement choice for daily-driven trucks, work trucks, and dependable street or towing builds. By packaging all three required harnesses together, it delivers a cleaner repair path for owners and shops replacing the complete inner injector harness system. Verify truck year, engine application, connector style, and OE reference number before ordering.