Grimmspeed GRM040005 Hella Horn Wiring Harness Plug-and-Play

The GrimmSpeed GRM040005 Hella Horn Wiring Harness is a pre-assembled, OEM-quality wiring solution designed for clean and reliable Hella Horn installations. Built to pair directly with the GrimmSpeed BroTie Bracket, this harness eliminates the need to fabricate custom wiring from scratch and connects directly to the factory horn harness for a fast, hassle-free install.

GrimmSpeed engineered this harness without the Hella-supplied relay after testing confirmed the marginal decibel gain was not worth the added complexity, extra failure points, and additional wiring runs to the battery. The result is a simpler, more reliable harness that still delivers excellent horn performance. For those who want maximum output, the harness design remains adaptable for relay integration.

Key Features:

• Automotive-Grade 16-Gauge Wire — Minimizes resistance for maximum horn volume
• Heat Shrink Crimp Terminals — Sealed, crimp-on connections ensure a durable and weather-resistant bond
• Protective Wire Sleeving — Black braided sleeving provides a clean appearance while guarding against abrasion and stress
• Plug-and-Play with OEM Harness — Connects directly to the factory horn connector; installs and uninstalls in seconds
• No Relay Required — Simplified design eliminates unnecessary failure points without sacrificing performance

The GRM040005 is the ideal companion to the GrimmSpeed BroTie Bracket (GRM040004) for a complete, professional-looking Hella Horn upgrade.