MX-5 Miata NA8 1996-97 (BP-ZE, 1.8, OBD-II) → AMP EFI Microsquirt (auto)
MX-5 Miata NA8 1996-97 (BP-ZE, 1.8, OBD-II) — AMP EFI — Microsquirt
⚠ 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 | 38 wires · 7 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-B | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | SP-14V-1 | MICROSQUIRT-A-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | OEM-4-A | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | OEM-4-C | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | OEM-4-D | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | OEM-4-K | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | SP-GND-1 | MICROSQUIRT-A-22 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | SP-GND-1 | MICROSQUIRT-A-23 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | OEM-3-O | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | OEM-4-H | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | SP-0V-1 | MICROSQUIRT-A-18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | SP-0V-1 | MICROSQUIRT-A-19 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | SP-0V-1 | MICROSQUIRT-A-20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-3-I | MICROSQUIRT-A-28 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | OEM-4-E | MICROSQUIRT-A-32 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | OEM-4-G | MICROSQUIRT-A-4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-4-F | MICROSQUIRT-A-21 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-4-N | MICROSQUIRT-A-11 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-4-R | MICROSQUIRT-A-12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-4-U | MICROSQUIRT-A-9 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-4-V | MICROSQUIRT-A-10 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-4-W | MICROSQUIRT-A-9 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-4-X | MICROSQUIRT-A-10 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-3-B | MICROSQUIRT-A-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-3-F | MICROSQUIRT-A-27 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-3-G | MICROSQUIRT-A-25 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-1-A | MICROSQUIRT-A-8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-1-B | MICROSQUIRT-A-16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-1-G | MICROSQUIRT-A-17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-1-U | MICROSQUIRT-A-7 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W31 | OEM-4-L | MICROSQUIRT-A-35 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W32 | OEM-3-H | MICROSQUIRT-A-24 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W33 | OEM-3-N | MICROSQUIRT-A-29 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W34 | OEM-3-C | MICROSQUIRT-A-34 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W35 | OEM-3-K | MICROSQUIRT-A-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W36 | OEM-1-M | MICROSQUIRT-A-30 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W37 | OEM-1-C | MICROSQUIRT-A-31 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W38 | OEM-1-K | MICROSQUIRT-A-6 | 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 | MICROSQUIRT-A-28 | MICROSQUIRT-A-18 | open (OL) | 5 V sensor reference must not touch sensor ground | |
| 2 | MICROSQUIRT-A-28 | MICROSQUIRT-A-22 | open (OL) | 5 V sensor reference must not touch power ground | |
| 3 | MICROSQUIRT-A-18 | MICROSQUIRT-A-1 | open (OL) | sensor ground must not touch +12 V supply | |
| 4 | MICROSQUIRT-A-22 | MICROSQUIRT-A-1 | open (OL) | power ground must not touch +12 V supply | |
| 5 | MICROSQUIRT-A-28 | MICROSQUIRT-A-1 | open (OL) | 5 V sensor reference must not touch +12 V supply |
If any reading doesn't match, stop and get help before powering up.
Revisions
| Rev | Label | By | Date |
|---|---|---|---|
| No revisions yet. | |||
Schematic
Connectors
MICROSQUIRT-A
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | +12V In | — | W2 | — | 0.85 | SP-14V-1 | — | — | — |
| 10 | INJ 2 | — | W21 | — | 0.5 | OEM-4-V | — | — | — |
| 10 | INJ 2 | — | W23 | — | 0.5 | OEM-4-X | — | — | — |
| 11 | SPK B (IGN2) | — | W18 | — | 0.5 | OEM-4-N | — | — | — |
| 12 | SPK A (IGN 1) | — | W19 | — | 0.5 | OEM-4-R | — | — | — |
| 13 | RX | — | — | — | — | — | — | — | — |
| 14 | TX | — | — | — | — | — | — | — | — |
| 15 | BOOT LOAD | — | — | — | — | — | — | — | — |
| 16 | ALED | — | W28 | — | 0.5 | OEM-1-B | — | — | — |
| 17 | WLED | — | W29 | — | 0.5 | OEM-1-G | — | — | — |
| 18 | Sensor Ground | — | W11 | — | 0.5 | SP-0V-1 | — | — | — |
| 19 | Serial Ground | — | W12 | — | 0.5 | SP-0V-1 | — | — | — |
| 2 | CANH | — | — | — | — | — | — | — | — |
| 20 | Sensor Ground | — | W13 | — | 0.5 | SP-0V-1 | — | — | — |
| 21 | VR2- | — | W17 | — | 0.5 | OEM-4-F | — | — | — |
| 22 | POWER GROUND | — | W7 | — | 0.85 | SP-GND-1 | — | — | — |
| 23 | POWER GROUND | — | W8 | — | 0.85 | SP-GND-1 | — | — | — |
| 24 | MAP | — | W32 | — | 0.5 | OEM-3-H | — | — | — |
| 25 | CLT | — | W26 | — | 0.5 | OEM-3-G | — | — | — |
| 26 | MAT | — | W35 | — | 0.5 | OEM-3-K | — | — | — |
| 27 | TPS | — | W25 | — | 0.5 | OEM-3-F | — | — | — |
| 28 | TPS VREF (5V) | — | W14 | — | 0.5 | OEM-3-I | — | — | — |
| 29 | SPAREADC | — | W33 | — | 0.5 | OEM-3-N | — | — | — |
| 3 | CANL | — | — | — | — | — | — | — | — |
| 30 | OPTO+ | — | W36 | — | 0.5 | OEM-1-M | — | — | — |
| 31 | OPTO- | — | W37 | — | 0.5 | OEM-1-C | — | — | — |
| 32 | VR1+ | — | W15 | — | 0.5 | OEM-4-E | — | — | — |
| 33 | VR1- | — | — | — | — | — | — | — | — |
| 34 | O2 | — | W34 | — | 0.5 | OEM-3-C | — | — | — |
| 35 | TACHO | — | W31 | — | 0.5 | OEM-4-L | — | — | — |
| 4 | VR2+ | — | W16 | — | 0.5 | OEM-4-G | — | — | — |
| 5 | SPAREADC2 (MAF) | — | W24 | — | 0.5 | OEM-3-B | — | — | — |
| 6 | FLEX | — | W38 | — | 0.5 | OEM-1-K | — | — | — |
| 7 | FIDLE | — | W30 | — | 0.5 | OEM-1-U | — | — | — |
| 8 | FP (pump) | — | W27 | — | 0.5 | OEM-1-A | — | — | — |
| 9 | INJ 1 | — | W20 | — | 0.5 | OEM-4-U | — | — | — |
| 9 | INJ 1 | — | W22 | — | 0.5 | OEM-4-W | — | — | — |
OEM-1
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Cooling fan relay (low-side) | — | W27 | — | 0.5 | MICROSQUIRT-A-8 | — | — | — |
| B | A/C condenser fan relay | — | W28 | — | 0.5 | MICROSQUIRT-A-16 | — | — | — |
| C | Starter input (12V while cranking) | — | W37 | — | 0.5 | MICROSQUIRT-A-31 | — | — | — |
| E | Check engine light (MIL) | — | — | — | — | — | — | — | — |
| G | A/C clutch relay | — | W29 | — | 0.5 | MICROSQUIRT-A-17 | — | — | — |
| K | A/C pressure switch (A/C request) | — | W38 | — | 0.5 | MICROSQUIRT-A-6 | — | — | — |
| L | Clutch switch | — | — | — | — | — | — | — | — |
| M | Vehicle speed sensor (VSS) | — | W36 | — | 0.5 | MICROSQUIRT-A-30 | — | — | — |
| Q | Brake switch | — | — | — | — | — | — | — | — |
| U | Fuel pump relay (low-side) | — | W30 | — | 0.5 | MICROSQUIRT-A-7 | — | — | — |
OEM-3
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| B | MAF sensor input | — | W24 | — | 0.5 | MICROSQUIRT-A-5 | — | — | — |
| C | Front O2 sensor input | — | W34 | — | 0.5 | MICROSQUIRT-A-34 | — | — | — |
| D | Rear O2 sensor input | — | — | — | — | — | — | — | — |
| F | Throttle position (TPS) | — | W25 | — | 0.5 | MICROSQUIRT-A-27 | — | — | — |
| G | Engine coolant temp (CLT) | — | W26 | — | 0.5 | MICROSQUIRT-A-25 | — | — | — |
| H | EGR boost sensor | — | W32 | — | 0.5 | MICROSQUIRT-A-24 | — | — | — |
| I | +5V sensor reference | — | W14 | — | 0.5 | MICROSQUIRT-A-28 | — | — | — |
| J | EGR valve position sensor | — | — | — | — | — | — | — | — |
| K | Intake air temp (IAT) | — | W35 | — | 0.5 | MICROSQUIRT-A-26 | — | — | — |
| L | Idle switch (closed throttle) | — | — | — | — | — | — | — | — |
| M | Front O2 heater control | — | — | — | — | — | — | — | — |
| N | EGR boost sensor (2nd channel) | — | W33 | — | 0.5 | MICROSQUIRT-A-29 | — | — | — |
| O | Sensor ground | — | W9 | — | 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 | — | W3 | — | 0.85 | SP-GND-1 | — | — | — |
| B | ECU power +12V (main relay) | — | W1 | — | 0.85 | SP-14V-1 | — | — | — |
| C | Chassis ground | — | W4 | — | 0.85 | SP-GND-1 | — | — | — |
| D | Chassis ground | — | W5 | — | 0.85 | SP-GND-1 | — | — | — |
| E | Crank position (CKP) sensor | — | W15 | — | 0.5 | MICROSQUIRT-A-32 | — | — | — |
| F | CAS SGT (cam trigger) | — | W17 | — | 0.5 | MICROSQUIRT-A-21 | — | — | — |
| G | CAS SGC (cam sync) | — | W16 | — | 0.5 | MICROSQUIRT-A-4 | — | — | — |
| H | Crank pickup timing ground (CKP gnd) | — | W10 | — | 0.5 | SP-0V-1 | — | — | — |
| I | Permanent +12V (battery) | — | — | — | — | — | — | — | — |
| J | PRC solenoid (FPR control) | — | — | — | — | — | — | — | — |
| K | Chassis ground | — | W6 | — | 0.85 | SP-GND-1 | — | — | — |
| L | Tachometer output | — | W31 | — | 0.5 | MICROSQUIRT-A-35 | — | — | — |
| N | Ignition coil trigger (cyl 1&4) | — | W18 | — | 0.5 | MICROSQUIRT-A-11 | — | — | — |
| O | EGR vent solenoid | — | — | — | — | — | — | — | — |
| P | EGR vacuum solenoid | — | — | — | — | — | — | — | — |
| Q | Idle air control (IAC) valve | — | — | — | — | — | — | — | — |
| R | Ignition coil trigger (cyl 2&3) | — | W19 | — | 0.5 | MICROSQUIRT-A-12 | — | — | — |
| T | EVAP purge solenoid | — | — | — | — | — | — | — | — |
| U | Injector 1 (cyl 1) | — | W20 | — | 0.5 | MICROSQUIRT-A-9 | — | — | — |
| V | Injector 2 (cyl 2) | — | W21 | — | 0.5 | MICROSQUIRT-A-10 | — | — | — |
| W | Injector 3 (cyl 3) | — | W22 | — | 0.5 | MICROSQUIRT-A-9 | — | — | — |
| X | Injector 4 (cyl 4) | — | W23 | — | 0.5 | MICROSQUIRT-A-10 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W9 | — | 0.5 | OEM-3-O | — | — | — |
| 1 | — | — | W10 | — | 0.5 | OEM-4-H | — | — | — |
| 1 | — | — | W11 | — | 0.5 | MICROSQUIRT-A-18 | — | — | — |
| 1 | — | — | W12 | — | 0.5 | MICROSQUIRT-A-19 | — | — | — |
| 1 | — | — | W13 | — | 0.5 | MICROSQUIRT-A-20 | — | — | — |
SP-14V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W1 | — | 0.85 | OEM-4-B | — | — | — |
| 1 | — | — | W2 | — | 0.85 | MICROSQUIRT-A-1 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W3 | — | 0.85 | OEM-4-A | — | — | — |
| 1 | — | — | W4 | — | 0.85 | OEM-4-C | — | — | — |
| 1 | — | — | W5 | — | 0.85 | OEM-4-D | — | — | — |
| 1 | — | — | W6 | — | 0.85 | OEM-4-K | — | — | — |
| 1 | — | — | W7 | — | 0.85 | MICROSQUIRT-A-22 | — | — | — |
| 1 | — | — | W8 | — | 0.85 | MICROSQUIRT-A-23 | — | — | — |
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 | MICROSQUIRT-A-8 | FP (pump) | low_side_out | corroborated | |
| OEM-1-B | A/C condenser fan relay | low_side_out | MICROSQUIRT-A-16 | ALED | low_side_out | corroborated | |
| OEM-1-C | Starter input (12V while cranking) | digital_in | MICROSQUIRT-A-31 | OPTO- | digital_in | corroborated | |
| OEM-1-E | Check engine light (MIL) | low_side_out | — | — | — | corroborated | |
| OEM-1-G | A/C clutch relay | low_side_out | MICROSQUIRT-A-17 | WLED | low_side_out | corroborated | |
| OEM-1-K | A/C pressure switch (A/C request) | digital_in | MICROSQUIRT-A-6 | FLEX | digital_in | corroborated | |
| OEM-1-L | Clutch switch | digital_in | — | — | — | corroborated | |
| OEM-1-M | Vehicle speed sensor (VSS) | digital_in | MICROSQUIRT-A-30 | OPTO+ | digital_in | corroborated | |
| OEM-1-Q | Brake switch | digital_in | — | — | — | corroborated | |
| OEM-1-U | Fuel pump relay (low-side) | low_side_out | MICROSQUIRT-A-7 | FIDLE | low_side_out | corroborated | |
| OEM-3-B | MAF sensor input | analog_in | MICROSQUIRT-A-5 | SPAREADC2 (MAF) | analog_in | corroborated | |
| OEM-3-C | Front O2 sensor input | lambda_nb_in | MICROSQUIRT-A-34 | O2 | lambda_nb_in | corroborated | |
| OEM-3-D | Rear O2 sensor input | lambda_nb_in | — | — | — | corroborated | |
| OEM-3-F | Throttle position (TPS) | analog_in | MICROSQUIRT-A-27 | TPS | analog_in | corroborated | |
| OEM-3-G | Engine coolant temp (CLT) | temp_in | MICROSQUIRT-A-25 | CLT | temp_in | corroborated | |
| OEM-3-H | EGR boost sensor | analog_in | MICROSQUIRT-A-24 | MAP | analog_in | corroborated | |
| OEM-3-I | +5V sensor reference | vref | MICROSQUIRT-A-28 | TPS VREF (5V) | vref | corroborated | |
| OEM-3-J | EGR valve position sensor | analog_in | — | — | — | corroborated | |
| OEM-3-K | Intake air temp (IAT) | temp_in | MICROSQUIRT-A-26 | MAT | temp_in | corroborated | |
| OEM-3-L | Idle switch (closed throttle) | digital_in | — | — | — | corroborated | |
| OEM-3-M | Front O2 heater control | low_side_out | — | — | — | corroborated | |
| OEM-3-N | EGR boost sensor (2nd channel) | analog_in | MICROSQUIRT-A-29 | SPAREADC | analog_in | corroborated | |
| OEM-3-O | Sensor ground | sensor_ground | MICROSQUIRT-A-18 + MICROSQUIRT-A-19 + MICROSQUIRT-A-20 | Sensor Ground + Serial Ground + Sensor Ground | sensor_ground | corroborated | |
| OEM-3-P | Power steering pressure switch | digital_in | — | — | — | corroborated | |
| OEM-4-A | Chassis ground | ground | MICROSQUIRT-A-22 + MICROSQUIRT-A-23 | POWER GROUND + POWER GROUND | ground | corroborated | |
| OEM-4-B | ECU power +12V (main relay) | power_in | MICROSQUIRT-A-1 | +12V In | power_in | corroborated | |
| OEM-4-C | Chassis ground | ground | MICROSQUIRT-A-22 + MICROSQUIRT-A-23 | POWER GROUND + POWER GROUND | ground | corroborated | |
| OEM-4-D | Chassis ground | ground | MICROSQUIRT-A-22 + MICROSQUIRT-A-23 | POWER GROUND + POWER GROUND | ground | corroborated | |
| OEM-4-E | Crank position (CKP) sensor | trigger_in | MICROSQUIRT-A-32 | VR1+ | trigger_in | corroborated | |
| OEM-4-F | CAS SGT (cam trigger) | trigger_in | MICROSQUIRT-A-21 | VR2- | trigger_in | corroborated | |
| OEM-4-G | CAS SGC (cam sync) | trigger_in | MICROSQUIRT-A-4 | VR2+ | trigger_in | corroborated | |
| OEM-4-H | Crank pickup timing ground (CKP gnd) | sensor_ground | MICROSQUIRT-A-18 + MICROSQUIRT-A-19 + MICROSQUIRT-A-20 | Sensor Ground + Serial Ground + Sensor 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 | MICROSQUIRT-A-22 + MICROSQUIRT-A-23 | POWER GROUND + POWER GROUND | ground | corroborated | |
| OEM-4-L | Tachometer output | tacho_out | MICROSQUIRT-A-35 | TACHO | tacho_out | corroborated | |
| OEM-4-N | Ignition coil trigger (cyl 1&4) | ignition_out | MICROSQUIRT-A-11 | SPK B (IGN2) | 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 | MICROSQUIRT-A-12 | SPK A (IGN 1) | ignition_out | corroborated | |
| OEM-4-T | EVAP purge solenoid | low_side_out | — | — | — | corroborated | |
| OEM-4-U | Injector 1 (cyl 1) | injector_out | MICROSQUIRT-A-9 | INJ 1 | injector_out | corroborated | |
| OEM-4-V | Injector 2 (cyl 2) | injector_out | MICROSQUIRT-A-10 | INJ 2 | injector_out | corroborated | |
| OEM-4-W | Injector 3 (cyl 3) | injector_out | MICROSQUIRT-A-9 | INJ 1 | injector_out | corroborated | |
| OEM-4-X | Injector 4 (cyl 4) | injector_out | MICROSQUIRT-A-10 | INJ 2 | injector_out | corroborated |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-4-B | SP-14V-1 | 0.85 | no route | ECU power +12V (main relay) | — | |
| W2 | SP-14V-1 | MICROSQUIRT-A-1 | 0.85 | no route | +12V In | — | |
| W3 | OEM-4-A | SP-GND-1 | 0.85 | no route | Chassis ground | — | |
| W4 | OEM-4-C | SP-GND-1 | 0.85 | no route | Chassis ground | — | |
| W5 | OEM-4-D | SP-GND-1 | 0.85 | no route | Chassis ground | — | |
| W6 | OEM-4-K | SP-GND-1 | 0.85 | no route | Chassis ground | — | |
| W7 | SP-GND-1 | MICROSQUIRT-A-22 | 0.85 | no route | POWER GROUND | — | |
| W8 | SP-GND-1 | MICROSQUIRT-A-23 | 0.85 | no route | POWER GROUND | — | |
| W9 | OEM-3-O | SP-0V-1 | 0.5 | no route | Sensor ground | — | |
| W10 | OEM-4-H | SP-0V-1 | 0.5 | no route | Crank pickup timing ground (CKP gnd) | — | |
| W11 | SP-0V-1 | MICROSQUIRT-A-18 | 0.5 | no route | Sensor Ground | — | |
| W12 | SP-0V-1 | MICROSQUIRT-A-19 | 0.5 | no route | Serial Ground | — | |
| W13 | SP-0V-1 | MICROSQUIRT-A-20 | 0.5 | no route | Sensor Ground | — | |
| W14 | OEM-3-I | MICROSQUIRT-A-28 | 0.5 | no route | +5V sensor reference | — | |
| W15 | OEM-4-E | MICROSQUIRT-A-32 | 0.5 | no route | Crank position (CKP) sensor | — | |
| W16 | OEM-4-G | MICROSQUIRT-A-4 | 0.5 | no route | CAS SGC (cam sync) | — | |
| W17 | OEM-4-F | MICROSQUIRT-A-21 | 0.5 | no route | CAS SGT (cam trigger) | — | |
| W18 | OEM-4-N | MICROSQUIRT-A-11 | 0.5 | no route | Ignition coil trigger (cyl 1&4) | — | |
| W19 | OEM-4-R | MICROSQUIRT-A-12 | 0.5 | no route | Ignition coil trigger (cyl 2&3) | — | |
| W20 | OEM-4-U | MICROSQUIRT-A-9 | 0.5 | no route | Injector 1 (cyl 1) | — | |
| W21 | OEM-4-V | MICROSQUIRT-A-10 | 0.5 | no route | Injector 2 (cyl 2) | — | |
| W22 | OEM-4-W | MICROSQUIRT-A-9 | 0.5 | no route | Injector 3 (cyl 3) | — | |
| W23 | OEM-4-X | MICROSQUIRT-A-10 | 0.5 | no route | Injector 4 (cyl 4) | — | |
| W24 | OEM-3-B | MICROSQUIRT-A-5 | 0.5 | no route | MAF sensor input | — | |
| W25 | OEM-3-F | MICROSQUIRT-A-27 | 0.5 | no route | Throttle position (TPS) | — | |
| W26 | OEM-3-G | MICROSQUIRT-A-25 | 0.5 | no route | Engine coolant temp (CLT) | — | |
| W27 | OEM-1-A | MICROSQUIRT-A-8 | 0.5 | no route | Cooling fan relay (low-side) | — | |
| W28 | OEM-1-B | MICROSQUIRT-A-16 | 0.5 | no route | A/C condenser fan relay | — | |
| W29 | OEM-1-G | MICROSQUIRT-A-17 | 0.5 | no route | A/C clutch relay | — | |
| W30 | OEM-1-U | MICROSQUIRT-A-7 | 0.5 | no route | Fuel pump relay (low-side) | — | |
| W31 | OEM-4-L | MICROSQUIRT-A-35 | 0.5 | no route | Tachometer output | — | |
| W32 | OEM-3-H | MICROSQUIRT-A-24 | 0.5 | no route | EGR boost sensor | — | |
| W33 | OEM-3-N | MICROSQUIRT-A-29 | 0.5 | no route | EGR boost sensor (2nd channel) | — | |
| W34 | OEM-3-C | MICROSQUIRT-A-34 | 0.5 | no route | Front O2 sensor input | — | |
| W35 | OEM-3-K | MICROSQUIRT-A-26 | 0.5 | no route | Intake air temp (IAT) | — | |
| W36 | OEM-1-M | MICROSQUIRT-A-30 | 0.5 | no route | Vehicle speed sensor (VSS) | — | |
| W37 | OEM-1-C | MICROSQUIRT-A-31 | 0.5 | no route | Starter input (12V while cranking) | — | |
| W38 | OEM-1-K | MICROSQUIRT-A-6 | 0.5 | no route | A/C pressure switch (A/C request) | — |
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 (3)
| Severity | Code | Subject | Message |
|---|---|---|---|
| error | NET_MERGED | MICROSQUIRT-A-10 + OEM-4-V + OEM-4-X | 2 different OEM functions share one net: OEM-4-V Injector 2 (cyl 2); OEM-4-X Injector 4 (cyl 4) |
| error | NET_MERGED | MICROSQUIRT-A-9 + OEM-4-U + OEM-4-W | 2 different OEM functions share one net: OEM-4-U Injector 1 (cyl 1); OEM-4-W Injector 3 (cyl 3) |
| info | UNMAPPED | OEM | 13 optional OEM pins are not mapped: OEM-1-E Check engine light (MIL); 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-M Front O2 heater control; 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. Not wired: - OEM-4 I: Permanent +12V (battery): AMP EFI Microsquirt has no battery-constant input; not needed - OEM-3 M: Front O2 heater control: no free heater_low_side/low_side/relay_control/ls_hs/injector on AMP EFI Microsquirt - OEM-1 E: Check engine light (MIL): no free low_side/relay_control/heater_low_side/ls_hs/injector on AMP EFI Microsquirt - OEM-4 J: PRC solenoid (FPR control): no free low_side/relay_control/heater_low_side/ls_hs/injector on AMP EFI Microsquirt - OEM-4 O: EGR vent solenoid: no free low_side/relay_control/heater_low_side/ls_hs/injector on AMP EFI Microsquirt - OEM-4 P: EGR vacuum solenoid: no free low_side/relay_control/heater_low_side/ls_hs/injector on AMP EFI Microsquirt - OEM-4 Q: Idle air control (IAC) valve: no free low_side/relay_control/heater_low_side/ls_hs/injector on AMP EFI Microsquirt - OEM-4 T: EVAP purge solenoid: no free low_side/relay_control/heater_low_side/ls_hs/injector on AMP EFI Microsquirt - OEM-3 D: Rear O2 sensor input: no free o2_narrowband/analog_0_5 on AMP EFI Microsquirt - OEM-3 J: EGR valve position sensor: no free analog_0_5 on AMP EFI Microsquirt - OEM-1 L: Clutch switch: no free switch_in/frequency_in/analog_0_5 on AMP EFI Microsquirt - OEM-1 Q: Brake switch: no free switch_in/frequency_in/analog_0_5 on AMP EFI Microsquirt - OEM-3 L: Idle switch (closed throttle): no free switch_in/frequency_in/analog_0_5 on AMP EFI Microsquirt - OEM-3 P: Power steering pressure switch: no free switch_in/frequency_in/analog_0_5 on AMP EFI Microsquirt
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 | MSExtra: Microsquirt hardware 3.4 | http://www.msextra.com/doc/pdf/Microsquirt_Hardware-3.4.pdf | archive | 2026-10-05 | ad920d9160de |
| 3 | community_copy | Mellens.net: 1996 Mazda Miata wiring diagrams (FSM-derived) | http://www.mellens.net/mazda/mazda_miata_extra_manual/1996_wiring.pdf | — | — | — |