MX-5 Miata NA8 1996-97 (BP-ZE, 1.8, OBD-II) → Speeduino Speeduino v0.4 (auto)
MX-5 Miata NA8 1996-97 (BP-ZE, 1.8, OBD-II) — Speeduino — Speeduino
⚠ NOT CHECKED. Don't build from this.
Drawn by Michael Gnankou · Rev 0 · draft · 2026-10-12
Before you start
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.
| Status | draft · not yet verified: nobody has reported building and running this harness |
|---|---|
| Open errors | 2: read the Findings page before cutting any wire |
| Size of the job | 34 wires · 6 connectors · 0 part lines |
| Tools | Crimp and extraction tools for each terminal family (see Connectors) · wire strippers · multimeter · heat gun + heat-shrink |
| Order of work | 1. Check every part against the parts list. 2. Cut and label every wire (labels: Export → Wire labels). 3. Crimp and pin connector by connector, ticking the build checklist. 4. Run the bench test with nothing plugged in and the battery disconnected. 5. Only then connect the ECU and power up. |
Build checklist
Tick each box as you go. Continuity: meter from end to end, expect under 1 Ω.
| Wire | From | To | Gauge | Colour | Cut | Label | Crimp A | Crimp B | Pin A | Pin B | Continuity |
|---|---|---|---|---|---|---|---|---|---|---|---|
| W1 | OEM-4-A | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | OEM-4-C | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | OEM-4-D | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | OEM-4-K | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | SP-GND-1 | SPEEDUINO-A-10 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | SP-GND-1 | SPEEDUINO-A-9 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | OEM-3-O | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | OEM-4-H | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | SP-0V-1 | SPEEDUINO-A-12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | SP-0V-1 | SPEEDUINO-A-23 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | OEM-3-I | SPEEDUINO-A-13 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | OEM-4-E | SPEEDUINO-A-25 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-4-G | SPEEDUINO-A-24 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-4-F | SPEEDUINO-A-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | OEM-4-N | SPEEDUINO-A-7 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | OEM-4-R | SPEEDUINO-A-34 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-4-U | SPEEDUINO-A-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-4-V | SPEEDUINO-A-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-4-W | SPEEDUINO-A-3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-4-X | SPEEDUINO-A-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-3-F | SPEEDUINO-A-22 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-3-G | SPEEDUINO-A-19 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-1-A | SPEEDUINO-A-16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-1-B | SPEEDUINO-A-15 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-1-G | SPEEDUINO-A-36 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-1-U | SPEEDUINO-A-35 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-3-M | SPEEDUINO-A-37 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-1-E | SPEEDUINO-A-38 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-4-L | SPEEDUINO-A-17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-3-H | SPEEDUINO-A-11 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W31 | OEM-3-C | SPEEDUINO-A-21 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W32 | OEM-3-K | SPEEDUINO-A-20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W33 | OEM-1-M | SPEEDUINO-A-14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W34 | OEM-1-C | SPEEDUINO-A-18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ |
Bench test (before first power-up)
Battery disconnected, ECU and every sensor unplugged. Meter on resistance. Each pair below must read open (OL): a reading means a pinched wire, a stray strand or a mis-pinned cavity. Then check continuity of every wire (last column of the build checklist).
| # | Probe A | Probe B | Expect | Why | Reading |
|---|---|---|---|---|---|
| 1 | SPEEDUINO-A-13 | SPEEDUINO-A-10 | open (OL) | 5 V sensor reference must not touch power ground | |
| 2 | SPEEDUINO-A-13 | SPEEDUINO-A-12 | open (OL) | 5 V sensor reference must not touch sensor ground |
If any reading doesn't match, stop and get help before powering up.
Revisions
| Rev | Label | By | Date |
|---|---|---|---|
| No revisions yet. | |||
Schematic
Connectors
OEM-1
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Cooling fan relay (low-side) | — | W23 | — | 0.5 | SPEEDUINO-A-16 | — | — | — |
| B | A/C condenser fan relay | — | W24 | — | 0.5 | SPEEDUINO-A-15 | — | — | — |
| C | Starter input (12V while cranking) | — | W34 | — | 0.5 | SPEEDUINO-A-18 | — | — | — |
| E | Check engine light (MIL) | — | W28 | — | 0.5 | SPEEDUINO-A-38 | — | — | — |
| G | A/C clutch relay | — | W25 | — | 0.5 | SPEEDUINO-A-36 | — | — | — |
| K | A/C pressure switch (A/C request) | — | — | — | — | — | — | — | — |
| L | Clutch switch | — | — | — | — | — | — | — | — |
| M | Vehicle speed sensor (VSS) | — | W33 | — | 0.5 | SPEEDUINO-A-14 | — | — | — |
| Q | Brake switch | — | — | — | — | — | — | — | — |
| U | Fuel pump relay (low-side) | — | W26 | — | 0.5 | SPEEDUINO-A-35 | — | — | — |
OEM-3
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| B | MAF sensor input | — | — | — | — | — | — | — | — |
| C | Front O2 sensor input | — | W31 | — | 0.5 | SPEEDUINO-A-21 | — | — | — |
| D | Rear O2 sensor input | — | — | — | — | — | — | — | — |
| F | Throttle position (TPS) | — | W21 | — | 0.5 | SPEEDUINO-A-22 | — | — | — |
| G | Engine coolant temp (CLT) | — | W22 | — | 0.5 | SPEEDUINO-A-19 | — | — | — |
| H | EGR boost sensor | — | W30 | — | 0.5 | SPEEDUINO-A-11 | — | — | — |
| I | +5V sensor reference | — | W11 | — | 0.5 | SPEEDUINO-A-13 | — | — | — |
| J | EGR valve position sensor | — | — | — | — | — | — | — | — |
| K | Intake air temp (IAT) | — | W32 | — | 0.5 | SPEEDUINO-A-20 | — | — | — |
| L | Idle switch (closed throttle) | — | — | — | — | — | — | — | — |
| M | Front O2 heater control | — | W27 | — | 0.5 | SPEEDUINO-A-37 | — | — | — |
| N | EGR boost sensor (2nd channel) | — | — | — | — | — | — | — | — |
| O | Sensor ground | — | W7 | — | 0.5 | SP-0V-1 | — | — | — |
| P | Power steering pressure switch | — | — | — | — | — | — | — | — |
OEM-4
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Chassis ground | — | W1 | — | 0.85 | SP-GND-1 | — | — | — |
| B | ECU power +12V (main relay) | — | — | — | — | — | — | — | — |
| C | Chassis ground | — | W2 | — | 0.85 | SP-GND-1 | — | — | — |
| D | Chassis ground | — | W3 | — | 0.85 | SP-GND-1 | — | — | — |
| E | Crank position (CKP) sensor | — | W12 | — | 0.5 | SPEEDUINO-A-25 | — | — | — |
| F | CAS SGT (cam trigger) | — | W14 | — | 0.5 | SPEEDUINO-A-26 | — | — | — |
| G | CAS SGC (cam sync) | — | W13 | — | 0.5 | SPEEDUINO-A-24 | — | — | — |
| H | Crank pickup timing ground (CKP gnd) | — | W8 | — | 0.5 | SP-0V-1 | — | — | — |
| I | Permanent +12V (battery) | — | — | — | — | — | — | — | — |
| J | PRC solenoid (FPR control) | — | — | — | — | — | — | — | — |
| K | Chassis ground | — | W4 | — | 0.85 | SP-GND-1 | — | — | — |
| L | Tachometer output | — | W29 | — | 0.5 | SPEEDUINO-A-17 | — | — | — |
| N | Ignition coil trigger (cyl 1&4) | — | W15 | — | 0.5 | SPEEDUINO-A-7 | — | — | — |
| O | EGR vent solenoid | — | — | — | — | — | — | — | — |
| P | EGR vacuum solenoid | — | — | — | — | — | — | — | — |
| Q | Idle air control (IAC) valve | — | — | — | — | — | — | — | — |
| R | Ignition coil trigger (cyl 2&3) | — | W16 | — | 0.5 | SPEEDUINO-A-34 | — | — | — |
| T | EVAP purge solenoid | — | — | — | — | — | — | — | — |
| U | Injector 1 (cyl 1) | — | W17 | — | 0.5 | SPEEDUINO-A-1 | — | — | — |
| V | Injector 2 (cyl 2) | — | W18 | — | 0.5 | SPEEDUINO-A-2 | — | — | — |
| W | Injector 3 (cyl 3) | — | W19 | — | 0.5 | SPEEDUINO-A-3 | — | — | — |
| X | Injector 4 (cyl 4) | — | W20 | — | 0.5 | SPEEDUINO-A-5 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W7 | — | 0.5 | OEM-3-O | — | — | — |
| 1 | — | — | W8 | — | 0.5 | OEM-4-H | — | — | — |
| 1 | — | — | W9 | — | 0.5 | SPEEDUINO-A-12 | — | — | — |
| 1 | — | — | W10 | — | 0.5 | SPEEDUINO-A-23 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W1 | — | 0.85 | OEM-4-A | — | — | — |
| 1 | — | — | W2 | — | 0.85 | OEM-4-C | — | — | — |
| 1 | — | — | W3 | — | 0.85 | OEM-4-D | — | — | — |
| 1 | — | — | W4 | — | 0.85 | OEM-4-K | — | — | — |
| 1 | — | — | W5 | — | 0.85 | SPEEDUINO-A-10 | — | — | — |
| 1 | — | — | W6 | — | 0.85 | SPEEDUINO-A-9 | — | — | — |
SPEEDUINO-A
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Injector 1 | — | W17 | — | 0.5 | OEM-4-U | — | — | — |
| 10 | Ground | — | W5 | — | 0.85 | SP-GND-1 | — | — | — |
| 11 | MAP sensor (0-5V) | — | W30 | — | 0.5 | OEM-3-H | — | — | — |
| 12 | Ground | — | W9 | — | 0.5 | SP-0V-1 | — | — | — |
| 13 | 5V | — | W11 | — | 0.5 | OEM-3-I | — | — | — |
| 14 | Proto area 1 (flex fuel) | — | W33 | — | 0.5 | OEM-1-M | — | — | — |
| 15 | Proto area 2 (fan) | — | W24 | — | 0.5 | OEM-1-B | — | — | — |
| 16 | Proto area 3 (fuel pump) | — | W23 | — | 0.5 | OEM-1-A | — | — | — |
| 17 | Proto area 4 (tachometer) | — | W29 | — | 0.5 | OEM-4-L | — | — | — |
| 18 | Proto area 5 (clutch) | — | W34 | — | 0.5 | OEM-1-C | — | — | — |
| 19 | Coolant temp (CLT) | — | W22 | — | 0.5 | OEM-3-G | — | — | — |
| 2 | Injector 2 | — | W18 | — | 0.5 | OEM-4-V | — | — | — |
| 20 | Inlet air temp (IAT) | — | W32 | — | 0.5 | OEM-3-K | — | — | — |
| 21 | O2 sensor | — | W31 | — | 0.5 | OEM-3-C | — | — | — |
| 22 | TPS input | — | W21 | — | 0.5 | OEM-3-F | — | — | — |
| 23 | Ground | — | W10 | — | 0.5 | SP-0V-1 | — | — | — |
| 24 | Cam input / VR2+ | — | W13 | — | 0.5 | OEM-4-G | — | — | — |
| 25 | Crank input / VR1+ | — | W12 | — | 0.5 | OEM-4-E | — | — | — |
| 26 | VR2- | — | W14 | — | 0.5 | OEM-4-F | — | — | — |
| 27 | VR1- | — | — | — | — | — | — | — | — |
| 28 | 5V | — | — | — | — | — | — | — | — |
| 29 | Idle stepper 2B | — | — | — | — | — | — | — | — |
| 3 | Injector 3 | — | W19 | — | 0.5 | OEM-4-W | — | — | — |
| 30 | Idle stepper 2A | — | — | — | — | — | — | — | — |
| 31 | Idle stepper 1A | — | — | — | — | — | — | — | — |
| 32 | Idle stepper 1B | — | — | — | — | — | — | — | — |
| 33 | Ignition 3 | — | — | — | — | — | — | — | — |
| 34 | Ignition 2 | — | W16 | — | 0.5 | OEM-4-R | — | — | — |
| 35 | Boost | — | W26 | — | 0.5 | OEM-1-U | — | — | — |
| 36 | Idle 2 (3-wire idle) | — | W25 | — | 0.5 | OEM-1-G | — | — | — |
| 37 | PWM idle | — | W27 | — | 0.5 | OEM-3-M | — | — | — |
| 38 | VVT | — | W28 | — | 0.5 | OEM-1-E | — | — | — |
| 5 | Injector 4 | — | W20 | — | 0.5 | OEM-4-X | — | — | — |
| 7 | Ignition 1 | — | W15 | — | 0.5 | OEM-4-N | — | — | — |
| 8 | Ignition 4 | — | — | — | — | — | — | — | — |
| 9 | Ground | — | W6 | — | 0.85 | SP-GND-1 | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| OEM-1-A | Cooling fan relay (low-side) | low_side_out | SPEEDUINO-A-16 | Proto area 3 (fuel pump) | low_side_out | corroborated | |
| OEM-1-B | A/C condenser fan relay | low_side_out | SPEEDUINO-A-15 | Proto area 2 (fan) | low_side_out | corroborated | |
| OEM-1-C | Starter input (12V while cranking) | digital_in | SPEEDUINO-A-18 | Proto area 5 (clutch) | digital_in | corroborated | |
| OEM-1-E | Check engine light (MIL) | low_side_out | SPEEDUINO-A-38 | VVT | low_side_out | corroborated | |
| OEM-1-G | A/C clutch relay | low_side_out | SPEEDUINO-A-36 | Idle 2 (3-wire idle) | low_side_out | corroborated | |
| OEM-1-K | A/C pressure switch (A/C request) | digital_in | — | — | — | corroborated | |
| OEM-1-L | Clutch switch | digital_in | — | — | — | corroborated | |
| OEM-1-M | Vehicle speed sensor (VSS) | digital_in | SPEEDUINO-A-14 | Proto area 1 (flex fuel) | digital_in | corroborated | |
| OEM-1-Q | Brake switch | digital_in | — | — | — | corroborated | |
| OEM-1-U | Fuel pump relay (low-side) | low_side_out | SPEEDUINO-A-35 | Boost | low_side_out | corroborated | |
| OEM-3-B | MAF sensor input | analog_in | — | — | — | corroborated | |
| OEM-3-C | Front O2 sensor input | lambda_nb_in | SPEEDUINO-A-21 | O2 sensor | lambda_nb_in | corroborated | |
| OEM-3-D | Rear O2 sensor input | lambda_nb_in | — | — | — | corroborated | |
| OEM-3-F | Throttle position (TPS) | analog_in | SPEEDUINO-A-22 | TPS input | analog_in | corroborated | |
| OEM-3-G | Engine coolant temp (CLT) | temp_in | SPEEDUINO-A-19 | Coolant temp (CLT) | temp_in | corroborated | |
| OEM-3-H | EGR boost sensor | analog_in | SPEEDUINO-A-11 | MAP sensor (0-5V) | analog_in | corroborated | |
| OEM-3-I | +5V sensor reference | vref | SPEEDUINO-A-13 | 5V | vref | corroborated | |
| OEM-3-J | EGR valve position sensor | analog_in | — | — | — | corroborated | |
| OEM-3-K | Intake air temp (IAT) | temp_in | SPEEDUINO-A-20 | Inlet air temp (IAT) | temp_in | corroborated | |
| OEM-3-L | Idle switch (closed throttle) | digital_in | — | — | — | corroborated | |
| OEM-3-M | Front O2 heater control | low_side_out | SPEEDUINO-A-37 | PWM idle | low_side_out | corroborated | |
| OEM-3-N | EGR boost sensor (2nd channel) | analog_in | — | — | — | corroborated | |
| OEM-3-O | Sensor ground | sensor_ground | SPEEDUINO-A-12 + SPEEDUINO-A-23 | Ground + Ground | sensor_ground | corroborated | |
| OEM-3-P | Power steering pressure switch | digital_in | — | — | — | corroborated | |
| OEM-4-A | Chassis ground | ground | SPEEDUINO-A-10 + SPEEDUINO-A-9 | Ground + Ground | ground | corroborated | |
| OEM-4-B | ECU power +12V (main relay) | power_in | — | — | — | corroborated | |
| OEM-4-C | Chassis ground | ground | SPEEDUINO-A-10 + SPEEDUINO-A-9 | Ground + Ground | ground | corroborated | |
| OEM-4-D | Chassis ground | ground | SPEEDUINO-A-10 + SPEEDUINO-A-9 | Ground + Ground | ground | corroborated | |
| OEM-4-E | Crank position (CKP) sensor | trigger_in | SPEEDUINO-A-25 | Crank input / VR1+ | trigger_in | corroborated | |
| OEM-4-F | CAS SGT (cam trigger) | trigger_in | SPEEDUINO-A-26 | VR2- | trigger_in | corroborated | |
| OEM-4-G | CAS SGC (cam sync) | trigger_in | SPEEDUINO-A-24 | Cam input / VR2+ | trigger_in | corroborated | |
| OEM-4-H | Crank pickup timing ground (CKP gnd) | sensor_ground | SPEEDUINO-A-12 + SPEEDUINO-A-23 | Ground + Ground | sensor_ground | corroborated | |
| OEM-4-I | Permanent +12V (battery) | power_in | — | — | — | corroborated | |
| OEM-4-J | PRC solenoid (FPR control) | low_side_out | — | — | — | corroborated | |
| OEM-4-K | Chassis ground | ground | SPEEDUINO-A-10 + SPEEDUINO-A-9 | Ground + Ground | ground | corroborated | |
| OEM-4-L | Tachometer output | tacho_out | SPEEDUINO-A-17 | Proto area 4 (tachometer) | tacho_out | corroborated | |
| OEM-4-N | Ignition coil trigger (cyl 1&4) | ignition_out | SPEEDUINO-A-7 | Ignition 1 | ignition_out | corroborated | |
| OEM-4-O | EGR vent solenoid | low_side_out | — | — | — | corroborated | |
| OEM-4-P | EGR vacuum solenoid | low_side_out | — | — | — | corroborated | |
| OEM-4-Q | Idle air control (IAC) valve | low_side_out | — | — | — | corroborated | |
| OEM-4-R | Ignition coil trigger (cyl 2&3) | ignition_out | SPEEDUINO-A-34 | Ignition 2 | ignition_out | corroborated | |
| OEM-4-T | EVAP purge solenoid | low_side_out | — | — | — | corroborated | |
| OEM-4-U | Injector 1 (cyl 1) | injector_out | SPEEDUINO-A-1 | Injector 1 | injector_out | corroborated | |
| OEM-4-V | Injector 2 (cyl 2) | injector_out | SPEEDUINO-A-2 | Injector 2 | injector_out | corroborated | |
| OEM-4-W | Injector 3 (cyl 3) | injector_out | SPEEDUINO-A-3 | Injector 3 | injector_out | corroborated | |
| OEM-4-X | Injector 4 (cyl 4) | injector_out | SPEEDUINO-A-5 | Injector 4 | injector_out | corroborated |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-4-A | SP-GND-1 | 0.85 | no route | Chassis ground | — | |
| W2 | OEM-4-C | SP-GND-1 | 0.85 | no route | Chassis ground | — | |
| W3 | OEM-4-D | SP-GND-1 | 0.85 | no route | Chassis ground | — | |
| W4 | OEM-4-K | SP-GND-1 | 0.85 | no route | Chassis ground | — | |
| W5 | SP-GND-1 | SPEEDUINO-A-10 | 0.85 | no route | Ground | — | |
| W6 | SP-GND-1 | SPEEDUINO-A-9 | 0.85 | no route | Ground | — | |
| W7 | OEM-3-O | SP-0V-1 | 0.5 | no route | Sensor ground | — | |
| W8 | OEM-4-H | SP-0V-1 | 0.5 | no route | Crank pickup timing ground (CKP gnd) | — | |
| W9 | SP-0V-1 | SPEEDUINO-A-12 | 0.5 | no route | Ground | — | |
| W10 | SP-0V-1 | SPEEDUINO-A-23 | 0.5 | no route | Ground | — | |
| W11 | OEM-3-I | SPEEDUINO-A-13 | 0.5 | no route | +5V sensor reference | — | |
| W12 | OEM-4-E | SPEEDUINO-A-25 | 0.5 | no route | Crank position (CKP) sensor | — | |
| W13 | OEM-4-G | SPEEDUINO-A-24 | 0.5 | no route | CAS SGC (cam sync) | — | |
| W14 | OEM-4-F | SPEEDUINO-A-26 | 0.5 | no route | CAS SGT (cam trigger) | — | |
| W15 | OEM-4-N | SPEEDUINO-A-7 | 0.5 | no route | Ignition coil trigger (cyl 1&4) | — | |
| W16 | OEM-4-R | SPEEDUINO-A-34 | 0.5 | no route | Ignition coil trigger (cyl 2&3) | — | |
| W17 | OEM-4-U | SPEEDUINO-A-1 | 0.5 | no route | Injector 1 (cyl 1) | — | |
| W18 | OEM-4-V | SPEEDUINO-A-2 | 0.5 | no route | Injector 2 (cyl 2) | — | |
| W19 | OEM-4-W | SPEEDUINO-A-3 | 0.5 | no route | Injector 3 (cyl 3) | — | |
| W20 | OEM-4-X | SPEEDUINO-A-5 | 0.5 | no route | Injector 4 (cyl 4) | — | |
| W21 | OEM-3-F | SPEEDUINO-A-22 | 0.5 | no route | Throttle position (TPS) | — | |
| W22 | OEM-3-G | SPEEDUINO-A-19 | 0.5 | no route | Engine coolant temp (CLT) | — | |
| W23 | OEM-1-A | SPEEDUINO-A-16 | 0.5 | no route | Cooling fan relay (low-side) | — | |
| W24 | OEM-1-B | SPEEDUINO-A-15 | 0.5 | no route | A/C condenser fan relay | — | |
| W25 | OEM-1-G | SPEEDUINO-A-36 | 0.5 | no route | A/C clutch relay | — | |
| W26 | OEM-1-U | SPEEDUINO-A-35 | 0.5 | no route | Fuel pump relay (low-side) | — | |
| W27 | OEM-3-M | SPEEDUINO-A-37 | 0.5 | no route | Front O2 heater control | — | |
| W28 | OEM-1-E | SPEEDUINO-A-38 | 0.5 | no route | Check engine light (MIL) | — | |
| W29 | OEM-4-L | SPEEDUINO-A-17 | 0.5 | no route | Tachometer output | — | |
| W30 | OEM-3-H | SPEEDUINO-A-11 | 0.5 | no route | EGR boost sensor | — | |
| W31 | OEM-3-C | SPEEDUINO-A-21 | 0.5 | no route | Front O2 sensor input | — | |
| W32 | OEM-3-K | SPEEDUINO-A-20 | 0.5 | no route | Intake air temp (IAT) | — | |
| W33 | OEM-1-M | SPEEDUINO-A-14 | 0.5 | no route | Vehicle speed sensor (VSS) | — | |
| W34 | OEM-1-C | SPEEDUINO-A-18 | 0.5 | no route | Starter input (12V while cranking) | — |
Bill of materials
| Category | Part number | Manufacturer | Description | Qty | Unit |
|---|
ECU setup sheet
| Role | Engine ref | Engine signal | Sensor | ECU point | ECU function | ECU class | Setup flag |
|---|---|---|---|---|---|---|---|
| No configured channels. | |||||||
Findings
Open (7)
| Severity | Code | Subject | Message |
|---|---|---|---|
| error | REQUIRED_UNMAPPED | OEM-3-B | Required OEM function "MAF sensor input" (analog_in) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-4-B | Required OEM function "ECU power +12V (main relay)" (power_in) is not connected to the new ECU. |
| warn | LOAD_UNKNOWN | SPEEDUINO-A-15 | SPEEDUINO-A-15 "Proto area 2 (fan)" drives OEM-1-B A/C condenser fan relay (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | LOAD_UNKNOWN | SPEEDUINO-A-16 | SPEEDUINO-A-16 "Proto area 3 (fuel pump)" drives OEM-1-A Cooling fan relay (low-side) (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | LOAD_UNKNOWN | SPEEDUINO-A-35 | SPEEDUINO-A-35 "Boost" drives OEM-1-U Fuel pump relay (low-side) (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | LOAD_UNKNOWN | SPEEDUINO-A-36 | SPEEDUINO-A-36 "Idle 2 (3-wire idle)" drives OEM-1-G A/C clutch relay (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| info | UNMAPPED | OEM | 13 optional OEM pins are not mapped: OEM-1-K A/C pressure switch (A/C request); OEM-1-L Clutch switch; OEM-1-Q Brake switch; OEM-3-D Rear O2 sensor input; OEM-3-J EGR valve position sensor; OEM-3-L Idle switch (closed throttle); OEM-3-N EGR boost sensor (2nd channel); OEM-3-P Power steering pressure switch; OEM-4-J PRC solenoid (FPR control); OEM-4-O EGR vent solenoid; OEM-4-P EGR vacuum solenoid; OEM-4-Q Idle air control (IAC) valve; OEM-4-T EVAP purge solenoid |
Accepted (1)
| Code | Subject | Reason | By |
|---|---|---|---|
| REQUIRED_UNMAPPED | OEM-4-I | Battery-constant (memory) feed of the stock ECU: the new ECU has no such input, so it is not needed. | mapping-proposal |
Notes
Auto-mapped by auto_map() from the library pin data on 2026-10-11. Review every wire against both manuals before building. Open items: - Main-relay feed: no ecu_main_power pin on the stock or the new ECU - OEM-3 B: MAF sensor input: no free maf/analog_0_5 on Speeduino Speeduino - OEM-4 B: ECU power +12V (main relay): no rule for class ecu_main_power; wire by hand Not wired: - OEM-4 I: Permanent +12V (battery): Speeduino Speeduino has no battery-constant input; not needed - OEM-4 J: PRC solenoid (FPR control): no free low_side/relay_control/heater_low_side/ls_hs/injector on Speeduino Speeduino - OEM-4 O: EGR vent solenoid: no free low_side/relay_control/heater_low_side/ls_hs/injector on Speeduino Speeduino - OEM-4 P: EGR vacuum solenoid: no free low_side/relay_control/heater_low_side/ls_hs/injector on Speeduino Speeduino - OEM-4 Q: Idle air control (IAC) valve: no free low_side/relay_control/heater_low_side/ls_hs/injector on Speeduino Speeduino - OEM-4 T: EVAP purge solenoid: no free low_side/relay_control/heater_low_side/ls_hs/injector on Speeduino Speeduino - OEM-3 N: EGR boost sensor (2nd channel): no free map/analog_0_5 on Speeduino Speeduino - OEM-3 D: Rear O2 sensor input: no free o2_narrowband/analog_0_5 on Speeduino Speeduino - OEM-3 J: EGR valve position sensor: no free analog_0_5 on Speeduino Speeduino - OEM-1 K: A/C pressure switch (A/C request): no free switch_in/frequency_in/analog_0_5 on Speeduino Speeduino - OEM-1 L: Clutch switch: no free switch_in/frequency_in/analog_0_5 on Speeduino Speeduino - OEM-1 Q: Brake switch: no free switch_in/frequency_in/analog_0_5 on Speeduino Speeduino - OEM-3 L: Idle switch (closed throttle): no free switch_in/frequency_in/analog_0_5 on Speeduino Speeduino - OEM-3 P: Power steering pressure switch: no free switch_in/frequency_in/analog_0_5 on Speeduino Speeduino
Sources
| Reliability | Kind | Title | URL | Archive | Captured | SHA-256 |
|---|---|---|---|---|---|---|
| 4 | vendor_doc | AEM EMS 30-1720 Plug-and-Play adapter manual (1996-97 Miata) | https://static.summitracing.com/global/images/instructions/avm-30-1720.pdf | — | — | — |
| 4 | vendor_doc | Speeduino Manual (08/04/25) — V0.4 board IDC40 pinout & features | https://speeduino.com/Speeduino_manual.pdf | archive | 2026-10-05 | 21806bd29ef0 |
| 3 | community_copy | Mellens.net: 1996 Mazda Miata wiring diagrams (FSM-derived) | http://www.mellens.net/mazda/mazda_miata_extra_manual/1996_wiring.pdf | — | — | — |