Not confident with automotive wiring? Have a professional harness builder or tuner do it, or check your work before first power-up. A wiring mistake can damage the ECU, the engine or the car, or start a fire.
Components
| Ref | Kind | Part | Exclude from BOM |
|---|---|---|---|
| MICROSQUIRT-A | connector | ||
| OEM-1 | connector | ||
| OEM-2 | connector | ||
| SP-0V | splice | ||
| SP-14V | splice | ||
| SP-GND | splice |
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Cut list
Lengths need a layout (0 of 35 routed).
| Wire | From / To | Gauge | Signal |
|---|---|---|---|
| W1 | OEM-1-B / SP-14V-1 | 0.85 | ECU power +14V (main relay) |
| W2 | SP-14V-1 / MICROSQUIRT-A-1 | 0.85 | +12V In |
| W3 | OEM-2-A / SP-GND-1 | 0.85 | Power ground |
| W4 | OEM-2-B / SP-GND-1 | 0.85 | Power ground |
| W5 | SP-GND-1 / MICROSQUIRT-A-22 | 0.85 | POWER GROUND |
| W6 | SP-GND-1 / MICROSQUIRT-A-23 | 0.85 | POWER GROUND |
| W7 | OEM-2-C / SP-0V-1 | 0.5 | Sensor ground (E2) |
| W8 | OEM-2-D / SP-0V-1 | 0.5 | Sensor ground (E2) |
| W9 | OEM-2-F / SP-0V-1 | 0.5 | MAF ground |
| W10 | SP-0V-1 / MICROSQUIRT-A-18 | 0.5 | Sensor Ground |
| W11 | SP-0V-1 / MICROSQUIRT-A-19 | 0.5 | Serial Ground |
| W12 | SP-0V-1 / MICROSQUIRT-A-20 | 0.5 | Sensor Ground |
| W13 | OEM-2-K / MICROSQUIRT-A-28 | 0.5 | +5V sensor supply |
| W14 | OEM-2-E / MICROSQUIRT-A-32 | 0.5 | Crank position (CAS NE) |
| W15 | OEM-2-G / MICROSQUIRT-A-4 | 0.5 | Cam position (CAS G) |
| W16 | OEM-1-G / MICROSQUIRT-A-11 | 0.5 | Ignition 1 (coils 1+4, wasted spark) |
| W17 | OEM-1-H / MICROSQUIRT-A-12 | 0.5 | Ignition 2 (coils 2+3, wasted spark) |
| W18 | OEM-2-U / MICROSQUIRT-A-9 | 0.5 | Injector 1 |
| W19 | OEM-2-V / MICROSQUIRT-A-10 | 0.5 | Injector 2 |
| W20 | OEM-2-Y / MICROSQUIRT-A-9 | 0.5 | Injector 3 |
| W21 | OEM-2-Z / MICROSQUIRT-A-10 | 0.5 | Injector 4 |
| W22 | OEM-1-J / MICROSQUIRT-A-8 | 0.5 | A/C relay |
| W23 | OEM-1-R / MICROSQUIRT-A-16 | 0.5 | Cooling fan relay |
| W24 | OEM-2-S / MICROSQUIRT-A-17 | 0.5 | Condenser fan relay |
| W25 | OEM-2-T / MICROSQUIRT-A-7 | 0.5 | Fuel pump relay |
| W26 | OEM-2-I / MICROSQUIRT-A-35 | 0.5 | Tachometer output |
| W27 | OEM-2-O / MICROSQUIRT-A-5 | 0.5 | Mass air flow (MAF) |
| W28 | OEM-2-M / MICROSQUIRT-A-27 | 0.5 | Throttle position (TPS) |
| W29 | OEM-2-N / MICROSQUIRT-A-34 | 0.5 | O2 sensor |
| W30 | OEM-2-Q / MICROSQUIRT-A-25 | 0.5 | Coolant temperature (ECT) |
| W31 | OEM-2-P / MICROSQUIRT-A-26 | 0.5 | Intake air temperature (IAT) |
| W32 | OEM-1-M / MICROSQUIRT-A-30 | 0.5 | Vehicle speed |
| W33 | OEM-1-C / MICROSQUIRT-A-31 | 0.5 | Start signal |
| W34 | OEM-1-P / MICROSQUIRT-A-6 | 0.5 | Power steering pressure switch |
| W35 | OEM-1-Q / MICROSQUIRT-A-29 | 0.5 | A/C request |
Bill of materials
No wire parts assigned: 35 wires need a wire part.
| Part number | Manufacturer | Description | Qty | Unit | Unit price | Buy |
|---|---|---|---|---|---|---|
| connector2 lines | ||||||
| 174515-6 | TE | AMP Multilock .040/.070 hybrid 22-pin female harness plug (Miata NA/NB ECU) | 1 | ea | Mouser ↗Digi-Key ↗Amazon ↗ | |
| 174516-6 | TE | AMP Multilock .040/.070 hybrid 26-pin female harness plug (Miata NA/NB ECU) | 1 | ea | Mouser ↗Digi-Key ↗Amazon ↗ | |