8′ MS3X Classic MegaSquirt Wiring Harness - Universal Flying Lead

Sequential-ready harness for your MS3X expansion—fully labeled, pre-terminated, and race-proven. The MegaSquirt MS3X Wiring Harness is an 8-foot flying lead harness purpose-built for the MS3X Expansion Board. Designed for clean, high-performance installs, it brings full support for sequential injection, coil-on-plug ignition, flex fuel, boost/nitrous control, and more. Constructed from TXL high-temp automotive-grade wire, each lead is color-coded and printed every 6 inches with its function and pin number—no paper tags, no guessing. The harness comes pre-crimped and pinned into a heavy-duty metal DB37 connector, ensuring excellent EMI/RFI resistance and long-term durability. Key Features: 8′ flying lead harness for MS3X Expansion Board TXL high-temperature automotive-grade wire Full color-coding with printed function and pin numbers every 6″ Pre-crimped DB37 connector (no solder cups) Heavy-duty metal DB37 hood for EMI/RFI shielding Supports sequential fuel and ignition, boost control, nitrous, flex fuel, VVT, and more Ideal for custom installations requiring MS3X expansion I/O Note: This harness is for the MS3X Expansion Board only. You will still need a separate main board harness (such as our 8′ MegaSquirt Wiring Harness) for the primary DB37 ECU connection. Common Supported Features: 8x Sequential fuel injector outputs (Injectors A–H) 8x Coil-on-plug ignition outputs (Spark A–H) Flex fuel input Boost control output Nitrous inputs and outputs (2-stage) Idle valve, VVT control, tach output, cam sync input Launch control, table switching, data logging triggers Second O2 sensor (EGO2), external MAP sensor, spare ADC Full Pinout and Wire Color Guide: Pin Printed Label Wire Gauge Base Color Stripe Color 1 MS3X-1: INJECTOR G 20ga White-WHT Dark blue-BLU 2 GROUND – no printed label 20ga Black-BLK no stripe 3 GROUND – no printed label 20ga Black-BLK no stripe 4 MS3X-4: INJECTOR F 20ga White-WHT Dark green-GRN 5 MS3X-5: FLEX FUEL INPUT 20ga Orange-ORN no stripe 6 MS3X-6: BOOST CONTROL 20ga Light green-LTGRN Red-RED 7 MS3X-7: INJECTOR E 20ga White-WHT Red-RED 8 GROUND – no printed label 20ga Black-BLK no stripe 9 MS3X-9: IDLE VALVE 20ga Light green-LTGRN Pink-PNK 10 MS3X-10: INJECTOR D 20ga White-WHT Pink-PNK 11 MS3X-11: LAUNCH CTRL IN 20ga Gray-GRY Red-RED 12 GROUND – no printed label 20ga Black-BLK no stripe 13 MS3X-13: INJECTOR C 20ga White-WHT Light green-LTGRN 14 MS3X-14: SPARK A 20ga Yellow-YEL no stripe 15 MS3X-15: SPARK C 20ga Yellow-YEL Light green-LTGRN 16 MS3X-16: INJECTOR B 20ga White-WHT Orange-ORN 17 GROUND – no printed label 20ga Black-BLK no stripe 18 MS3X-18: SPARK G 20ga Yellow-YEL Dark blue-BLU 19 MS3X-19: INJECTOR A 20ga White-WHT no stripe 20 MS3X-20: INJECTOR H 20ga White-WHT Purple-PUR 21 MS3X-21: SPARE ADC 20ga Light blue-LTBLU no stripe 22 MS3X-22: EGO2 20ga Light blue-LTBLU Dark blue-BLU 23 MS3X-23: EXT_MAP 20ga Light blue-LTBLU Red-RED 24 MS3X-24: NITROUS OUT 1 20ga Light green-LTGRN no stripe 25 MS3X-25: NITROUS OUT 2 20ga Light green-LTGRN Dark blue-BLU 26 MS3X-26: TACH OUTPUT 20ga Light green-LTGRN Orange-ORN 27 MS3X-27: VVT 20ga Light green-LTGRN Dark green-GRN 28 MS3X-28: TABLESWITCH IN 20ga Gray-GRY Purple-PUR 29 MS3X-29: NITROUS INPUT 20ga Gray-GRY Dark blue-BLU 30 MS3X-30: DATALOG INPUT 20ga Gray-GRY no stripe 31 MS3X-31: PT4 LOGIC OUTPUT 20ga Purple-PUR no stripe 32 MS3X-32: CAM INPUT 20ga Dark green-GRN no stripe 33 MS3X-33: SPARK B 20ga Yellow-YEL Orange-ORN 34 MS3X-34: SPARK D 20ga Yellow-YEL Pink-PNK 35 MS3X-35: SPARK E 20ga Yellow-YEL Red-RED 36 MS3X-36: SPARK F 20ga Yellow-YEL Dark green-GRN 37 MS3X-37: SPARK H 20ga Yellow-YEL Purple-PUR