Description
LMMF 89-99 3100 ECM and Harness Combo – ECM & Plug-and-Play Swap Wiring Kit
Looking for a complete, no-hassle wiring solution for your GM 3.1, 3100, or 3400 V6 build? The LMMF 89–99 3.1 / 3100 / 3400 Harness Bundle delivers a complete plug-and-play engine management system so you can get your car running without chasing parts, decoding wiring diagrams, or fighting old junkyard harnesses.
This complete wiring bundle includes a professionally built engine harness and tuned ECM, designed to simplify installs and provide reliable performance for demolition derby builds, engine swaps, and budget race setups.
It also allows builders to convert older 3.1 setups to the newer 3100/3400 style system, making it a great upgrade path for 1989–1999 GM 3.1 engines while remaining fully compatible with 1995–1999 3100 and 3400 engines.
What’s Included
- Professionally built & simplified 3100/3400-style engine harness
- Matched tuned ECM (Engine Control Module)
- Injector adapter harness included
- All new wiring, connectors, and quality components — no brittle junkyard wiring
Built for Reliability & Easy Installation
Every LMMF harness is built using brand-new wiring and connectors, eliminating the common failures found in used harnesses like cracked insulation, corroded terminals, and brittle wiring.
Each harness is professionally simplified, removing unnecessary sensors and circuits so you get a clean, easy-to-install wiring system that holds up under derby hits, vibration, and hard racing conditions.
The included ECM is tuned and matched to the harness, giving you a true ready-to-run engine management solution.
Perfect For
• Demolition derby builds
• 3.1 / 3100 / 3400 engine swaps
• Converting older 3.1 engines to newer 3100/3400 systems
• Budget performance builds
• Clean, simplified wiring installs
Why Builders Choose This Harness
• Plug-and-play wiring solution
• Converts older 3.1 engines to newer 3100/3400 systems
• Compatible with 1995–1999 3100 / 3400 engines
• Eliminates unreliable junkyard wiring
• Simplified setup for faster installs
Skip the frustration of building your own wiring or hunting down used parts. The LMMF 89–99 3.1 / 3100 / 3400 Harness Bundle gives you a complete ECM and wiring solution so you can plug it in, fire it up, and send it. 🔥
Pro Tip: Pair this harness bundle with W-Body tie rods and the W-Body rear trailing arm kit from our Steering & Suspension category to strengthen your front end and rear suspension for tough derby conditions.
Note: The injector adapter harness is not required when using this setup with 1996–1999 engines, but is included for compatibility with earlier configurations.
