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8' MegaSquirt Wiring Harness for MS3X

8′ MegaSquirt Wiring Harness for MS3X

5 out of 5 based on 4 customer ratings
(4 customer reviews)




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 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


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4 reviews for 8′ MegaSquirt Wiring Harness for MS3X

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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

    I understand that my Subaru has shielded wires on multiple sensors (oxygen, TPS, etc.). From the picture it appears that this product does not use shielded wiring?
  1. 0 votes
    Q I understand that my Subaru has shielded wires on multiple sensors (oxygen, TPS, etc.). From the ...... Read more
    Asked by Nate

    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.

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