Quick Links

8′ MegaSquirt Wiring Harness for MS3X

5 out of 5 based on 2 customer ratings
(2 customer reviews )
8' MegaSquirt Wiring Harness for MS3X



MegaSquirt MS3X Wiring Harness – 8 feet

  • 8′ of TXL High temp automotive grade wire.
  • Color coded wiring with labeling printed on the wire every 6 inches — no paper tags here!
  • All wiring is pre-crimped (NOT solder cupped!) to the DB37
  • Heavy duty metal DB37 hood for superior RFI/EMI shielding (no cheap plastic ‘metalized’ hoods used on our harnesses)
  • Use with MS3X Expansion board

This is the harness for the MS3X Expansion board. We’ve custom printed these to include all the inputs and outputs on the expansion board. Note that you will still need our regular MSHarness (or relay board/relaycable/wire bundle combination) for the main board DB37 – this is just the MS3X harness. Includes wiring for sequential injection, sequential coil on plug, nitrous, boost control, and more.

Printed LabelWire GaugeBase ColorStripe Color
1MS3X-1: INJECTOR G20gaWhite-WHTDark blue-BLU
2GROUND – no printed label20gaBlack-BLKno stripe
3GROUND – no printed label20gaBlack-BLKno stripe
4MS3X-4: INJECTOR F20gaWhite-WHTDark green-GRN
5MS3X-5: FLEX FUEL INPUT20gaOrange-ORNno stripe
6MS3X-6: BOOST CONTROL20gaLight green-LTGRNRed-RED
8GROUND – no printed label20gaBlack-BLKno stripe
9MS3X-9: IDLE VALVE20gaLight green-LTGRNPink-PNK
10MS3X-10: INJECTOR D20gaWhite-WHTPink-PNK
12GROUND – no printed label20gaBlack-BLKno stripe
13MS3X-13: INJECTOR C20gaWhite-WHTLight green-LTGRN
14MS3X-14: SPARK A20gaYellow-YELno stripe
15MS3X-15: SPARK C20gaYellow-YELLight green-LTGRN
16MS3X-16: INJECTOR B20gaWhite-WHTOrange-ORN
17GROUND – no printed label20gaBlack-BLKno stripe
18MS3X-18: SPARK G20gaYellow-YELDark blue-BLU
19MS3X-19: INJECTOR A20gaWhite-WHTno stripe
20MS3X-20: INJECTOR H20gaWhite-WHTPurple-PUR
21MS3X-21: SPARE ADC20gaLight blue-LTBLUno stripe
22MS3X-22: EGO220gaLight blue-LTBLUDark blue-BLU
23MS3X-23: EXT_MAP20gaLight blue-LTBLURed-RED
24MS3X-24: NITROUS OUT 120gaLight green-LTGRNno stripe
25MS3X-25: NITROUS OUT 220gaLight green-LTGRNDark blue-BLU
26MS3X-26: TACH OUTPUT20gaLight green-LTGRNOrange-ORN
27MS3X-27: VVT20gaLight green-LTGRNDark green-GRN
29MS3X-29: NITROUS INPUT20gaGray-GRYDark blue-BLU
30MS3X-30: DATALOG INPUT20gaGray-GRYno stripe
31MS3X-31: PT4 LOGIC OUTPUT20gaPurple-PURno stripe
32MS3X-32: CAM INPUT20gaDark green-GRNno stripe
33MS3X-33: SPARK B20gaYellow-YELOrange-ORN
34MS3X-34: SPARK D20gaYellow-YELPink-PNK
35MS3X-35: SPARK E20gaYellow-YELRed-RED
36MS3X-36: SPARK F20gaYellow-YELDark green-GRN
37MS3X-37: SPARK H20gaYellow-YELPurple-PUR


Customer reviews

Rated 5 out of 5 stars
2 reviews
4 stars 0 0 %
3 stars 0 0 %
2 stars 0 0 %
1 star 0 0 %

2 reviews for 8′ MegaSquirt Wiring Harness for MS3X

    Only logged in customers who have purchased this product may write a review.

    MS3 manuals at include wiring diagrams

    What sort of wiring does this harness use?

    • It uses 20 gauge TXL high temperature wire.

    Are all the pins populated?

    • Yes, this harness uses all the pins on the MS3X.

    If I am using an MS3 with MS3X, do I use this harness or the regular MS3 harness?

    • The MS3 with MS3X has two DB37 connectors, each of which use a harness. This harness connects to the upper (MS3X) connector, while the lower (main board) connector uses the regular MegaSquirt harness.

    Where is the harness assembled?

    • We build these harnesses in Gainesville, Georgia, USA.

    Questions & Answers

    1. 0 votes

      It does not. We use a shielded crank sensor wire as noise on the crank sensor is especially problematic. The others can be dealt with using hardware and/or software filtering inside the ECU.

    You may also like…

    • Seals-It Grommet – 0.75″ one piece

      5 out of 5

      Seals-It grommets make it easy to run wiring through your firewall without risking wearing the wiring, and help keep dirt and grime out of your interior. This one is a one piece, 0.75" inner diameter design that's perfect for any of our flying lead wiring...

      Add to cart