MX-5 Miata NB1 1999-00 (BP-4W) → AMP EFI Microsquirt (auto)
MX-5 Miata NB1 1999-00 (BP-4W) — AMP EFI — Microsquirt
⚠ NOT CHECKED. Don't build from this.
Drawn by Michael Gnankou · Rev 0 · draft · 2026-10-08
Before you start
| 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 | 33 wires · 7 connectors · 3 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-1-B | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | OEM-3-M | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | SP-14V-1 | MICROSQUIRT-A-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | OEM-3-A | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | OEM-3-B | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | OEM-3-C | 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-F | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | SP-0V-1 | MICROSQUIRT-A-18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | SP-0V-1 | MICROSQUIRT-A-19 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | SP-0V-1 | MICROSQUIRT-A-20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-2-I | MICROSQUIRT-A-28 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-2-J | MICROSQUIRT-A-32 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | OEM-2-H | MICROSQUIRT-A-4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | OEM-3-G | MICROSQUIRT-A-11 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-3-H | MICROSQUIRT-A-12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-3-W | MICROSQUIRT-A-9 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-3-X | MICROSQUIRT-A-10 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-1-I | MICROSQUIRT-A-8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-1-R | MICROSQUIRT-A-16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-1-S | MICROSQUIRT-A-17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-3-N | MICROSQUIRT-A-7 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-2-K | MICROSQUIRT-A-35 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-2-L | MICROSQUIRT-A-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-3-E | MICROSQUIRT-A-27 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-2-C | MICROSQUIRT-A-34 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-3-J | MICROSQUIRT-A-29 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-2-E | MICROSQUIRT-A-25 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-2-B | MICROSQUIRT-A-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W31 | OEM-2-D | MICROSQUIRT-A-30 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W32 | OEM-1-F | MICROSQUIRT-A-31 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W33 | OEM-1-G | 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-1 | MICROSQUIRT-A-18 | open (OL) | +12 V supply must not touch sensor ground | |
| 2 | MICROSQUIRT-A-1 | MICROSQUIRT-A-22 | open (OL) | +12 V supply must not touch power ground | |
| 3 | MICROSQUIRT-A-28 | MICROSQUIRT-A-18 | open (OL) | 5 V sensor reference must not touch sensor ground | |
| 4 | MICROSQUIRT-A-28 | MICROSQUIRT-A-22 | open (OL) | 5 V sensor reference must not touch power ground | |
| 5 | MICROSQUIRT-A-1 | MICROSQUIRT-A-28 | open (OL) | +12 V supply must not touch 5 V sensor reference |
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 | — | W3 | — | 0.85 | SP-14V-1 | — | — | — |
| 10 | INJ 2 | — | W19 | — | 0.5 | OEM-3-X | — | — | — |
| 11 | SPK B (IGN2) | — | W16 | — | 0.5 | OEM-3-G | — | — | — |
| 12 | SPK A (IGN 1) | — | W17 | — | 0.5 | OEM-3-H | — | — | — |
| 13 | RX | — | — | — | — | — | — | — | — |
| 14 | TX | — | — | — | — | — | — | — | — |
| 15 | BOOT LOAD | — | — | — | — | — | — | — | — |
| 16 | ALED | — | W21 | — | 0.5 | OEM-1-R | — | — | — |
| 17 | WLED | — | W22 | — | 0.5 | OEM-1-S | — | — | — |
| 18 | Sensor Ground | — | W10 | — | 0.5 | SP-0V-1 | — | — | — |
| 19 | Serial Ground | — | W11 | — | 0.5 | SP-0V-1 | — | — | — |
| 2 | CANH | — | — | — | — | — | — | — | — |
| 20 | Sensor Ground | — | W12 | — | 0.5 | SP-0V-1 | — | — | — |
| 21 | VR2- | — | — | — | — | — | — | — | — |
| 22 | POWER GROUND | — | W7 | — | 0.85 | SP-GND-1 | — | — | — |
| 23 | POWER GROUND | — | W8 | — | 0.85 | SP-GND-1 | — | — | — |
| 24 | MAP | — | — | — | — | — | — | — | — |
| 25 | CLT | — | W29 | — | 0.5 | OEM-2-E | — | — | — |
| 26 | MAT | — | W30 | — | 0.5 | OEM-2-B | — | — | — |
| 27 | TPS | — | W26 | — | 0.5 | OEM-3-E | — | — | — |
| 28 | TPS VREF (5V) | — | W13 | — | 0.5 | OEM-2-I | — | — | — |
| 29 | SPAREADC | — | W28 | — | 0.5 | OEM-3-J | — | — | — |
| 3 | CANL | — | — | — | — | — | — | — | — |
| 30 | OPTO+ | — | W31 | — | 0.5 | OEM-2-D | — | — | — |
| 31 | OPTO- | — | W32 | — | 0.5 | OEM-1-F | — | — | — |
| 32 | VR1+ | — | W14 | — | 0.5 | OEM-2-J | — | — | — |
| 33 | VR1- | — | — | — | — | — | — | — | — |
| 34 | O2 | — | W27 | — | 0.5 | OEM-2-C | — | — | — |
| 35 | TACHO | — | W24 | — | 0.5 | OEM-2-K | — | — | — |
| 4 | VR2+ | — | W15 | — | 0.5 | OEM-2-H | — | — | — |
| 5 | SPAREADC2 (MAF) | — | W25 | — | 0.5 | OEM-2-L | — | — | — |
| 6 | FLEX | — | W33 | — | 0.5 | OEM-1-G | — | — | — |
| 7 | FIDLE | — | W23 | — | 0.5 | OEM-3-N | — | — | — |
| 8 | FP (pump) | — | W20 | — | 0.5 | OEM-1-I | — | — | — |
| 9 | INJ 1 | — | W18 | — | 0.5 | OEM-3-W | — | — | — |
OEM-1
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Constant +12V | — | — | — | — | — | — | — | — |
| B | ECU power +14V (main relay) | — | W1 | — | 0.85 | SP-14V-1 | — | — | — |
| E | Malfunction indicator lamp (MIL) | — | — | — | — | — | — | — | — |
| F | Brake switch | — | W32 | — | 0.5 | MICROSQUIRT-A-31 | — | — | — |
| G | Power steering pressure switch | — | W33 | — | 0.5 | MICROSQUIRT-A-6 | — | — | — |
| I | Condenser fan relay | — | W20 | — | 0.5 | MICROSQUIRT-A-8 | — | — | — |
| O | Alternator control | — | — | — | — | — | — | — | — |
| P | A/C request | — | — | — | — | — | — | — | — |
| Q | Charge lamp | — | — | — | — | — | — | — | — |
| R | Cooling fan relay | — | W21 | — | 0.5 | MICROSQUIRT-A-16 | — | — | — |
| S | A/C clutch relay | — | W22 | — | 0.5 | MICROSQUIRT-A-17 | — | — | — |
| U | Front O2 heater | — | — | — | — | — | — | — | — |
| V | Neutral switch | — | — | — | — | — | — | — | — |
OEM-2
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Fuel tank pressure | — | — | — | — | — | — | — | — |
| B | Intake air temperature (IAT) | — | W30 | — | 0.5 | MICROSQUIRT-A-26 | — | — | — |
| C | Front O2 signal | — | W27 | — | 0.5 | MICROSQUIRT-A-34 | — | — | — |
| D | Vehicle speed | — | W31 | — | 0.5 | MICROSQUIRT-A-30 | — | — | — |
| E | Coolant temperature (ECT) | — | W29 | — | 0.5 | MICROSQUIRT-A-25 | — | — | — |
| F | Knock sensor | — | — | — | — | — | — | — | — |
| H | Cam position (CMP) | — | W15 | — | 0.5 | MICROSQUIRT-A-4 | — | — | — |
| I | +5V sensor supply | — | W13 | — | 0.5 | MICROSQUIRT-A-28 | — | — | — |
| J | Crank position (CKP) | — | W14 | — | 0.5 | MICROSQUIRT-A-32 | — | — | — |
| K | Tachometer output | — | W24 | — | 0.5 | MICROSQUIRT-A-35 | — | — | — |
| L | Mass air flow (MAF) | — | W25 | — | 0.5 | MICROSQUIRT-A-5 | — | — | — |
| M | EGR valve | — | — | — | — | — | — | — | — |
| N | EGR valve | — | — | — | — | — | — | — | — |
| O | EGR valve | — | — | — | — | — | — | — | — |
| P | EGR valve | — | — | — | — | — | — | — | — |
OEM-3
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Power ground | — | W4 | — | 0.85 | SP-GND-1 | — | — | — |
| B | Power ground | — | W5 | — | 0.85 | SP-GND-1 | — | — | — |
| C | Power ground | — | W6 | — | 0.85 | SP-GND-1 | — | — | — |
| E | Throttle position (TPS) | — | W26 | — | 0.5 | MICROSQUIRT-A-27 | — | — | — |
| F | Signal ground | — | W9 | — | 0.5 | SP-0V-1 | — | — | — |
| G | Ignition 1 (coils 1+4, wasted spark) | — | W16 | — | 0.5 | MICROSQUIRT-A-11 | — | — | — |
| H | Ignition 2 (coils 2+3, wasted spark) | — | W17 | — | 0.5 | MICROSQUIRT-A-12 | — | — | — |
| I | Clutch switch | — | — | — | — | — | — | — | — |
| J | Rear O2 signal | — | W28 | — | 0.5 | MICROSQUIRT-A-29 | — | — | — |
| K | Fuel level | — | — | — | — | — | — | — | — |
| L | Evap purge solenoid | — | — | — | — | — | — | — | — |
| M | ISC valve +14V feed | — | W2 | — | 0.85 | SP-14V-1 | — | — | — |
| N | Fuel pump relay | — | W23 | — | 0.5 | MICROSQUIRT-A-7 | — | — | — |
| O | ISC valve low side | — | — | — | — | — | — | — | — |
| Q | VICS solenoid (intake butterflies) | — | — | — | — | — | — | — | — |
| S | EGR boost sensor | — | — | — | — | — | — | — | — |
| T | EGR boost solenoid | — | — | — | — | — | — | — | — |
| U | Canister drain cut valve (CDCV) | — | — | — | — | — | — | — | — |
| V | Rear O2 heater | — | — | — | — | — | — | — | — |
| W | Injector 1 | — | W18 | — | 0.5 | MICROSQUIRT-A-9 | — | — | — |
| X | Injector 2 | — | W19 | — | 0.5 | MICROSQUIRT-A-10 | — | — | — |
| Y | Injector 3 | — | — | — | — | — | — | — | — |
| Z | Injector 4 | — | — | — | — | — | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W9 | — | 0.5 | OEM-3-F | — | — | — |
| 1 | — | — | W10 | — | 0.5 | MICROSQUIRT-A-18 | — | — | — |
| 1 | — | — | W11 | — | 0.5 | MICROSQUIRT-A-19 | — | — | — |
| 1 | — | — | W12 | — | 0.5 | MICROSQUIRT-A-20 | — | — | — |
SP-14V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W1 | — | 0.85 | OEM-1-B | — | — | — |
| 1 | — | — | W2 | — | 0.85 | OEM-3-M | — | — | — |
| 1 | — | — | W3 | — | 0.85 | MICROSQUIRT-A-1 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W4 | — | 0.85 | OEM-3-A | — | — | — |
| 1 | — | — | W5 | — | 0.85 | OEM-3-B | — | — | — |
| 1 | — | — | W6 | — | 0.85 | OEM-3-C | — | — | — |
| 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 | Constant +12V | power_in | — | — | — | single_source | |
| OEM-1-B | ECU power +14V (main relay) | power_in | MICROSQUIRT-A-1 | +12V In | power_in | single_source | |
| OEM-1-E | Malfunction indicator lamp (MIL) | low_side_out | — | — | — | single_source | |
| OEM-1-F | Brake switch | digital_in | MICROSQUIRT-A-31 | OPTO- | digital_in | single_source | |
| OEM-1-G | Power steering pressure switch | digital_in | MICROSQUIRT-A-6 | FLEX | digital_in | single_source | |
| OEM-1-I | Condenser fan relay | low_side_out | MICROSQUIRT-A-8 | FP (pump) | low_side_out | single_source | |
| OEM-1-O | Alternator control | low_side_out | — | — | — | single_source | |
| OEM-1-P | A/C request | digital_in | — | — | — | single_source | |
| OEM-1-Q | Charge lamp | low_side_out | — | — | — | single_source | |
| OEM-1-R | Cooling fan relay | low_side_out | MICROSQUIRT-A-16 | ALED | low_side_out | single_source | |
| OEM-1-S | A/C clutch relay | low_side_out | MICROSQUIRT-A-17 | WLED | low_side_out | single_source | |
| OEM-1-U | Front O2 heater | low_side_out | — | — | — | single_source | |
| OEM-1-V | Neutral switch | digital_in | — | — | — | single_source | |
| OEM-2-A | Fuel tank pressure | analog_in | — | — | — | single_source | |
| OEM-2-B | Intake air temperature (IAT) | temp_in | MICROSQUIRT-A-26 | MAT | temp_in | single_source | |
| OEM-2-C | Front O2 signal | lambda_nb_in | MICROSQUIRT-A-34 | O2 | lambda_nb_in | single_source | |
| OEM-2-D | Vehicle speed | digital_in | MICROSQUIRT-A-30 | OPTO+ | digital_in | single_source | |
| OEM-2-E | Coolant temperature (ECT) | temp_in | MICROSQUIRT-A-25 | CLT | temp_in | single_source | |
| OEM-2-F | Knock sensor | knock_in | — | — | — | single_source | |
| OEM-2-H | Cam position (CMP) | trigger_in | MICROSQUIRT-A-4 | VR2+ | trigger_in | single_source | |
| OEM-2-I | +5V sensor supply | vref | MICROSQUIRT-A-28 | TPS VREF (5V) | vref | single_source | |
| OEM-2-J | Crank position (CKP) | trigger_in | MICROSQUIRT-A-32 | VR1+ | trigger_in | single_source | |
| OEM-2-K | Tachometer output | tacho_out | MICROSQUIRT-A-35 | TACHO | tacho_out | single_source | |
| OEM-2-L | Mass air flow (MAF) | analog_in | MICROSQUIRT-A-5 | SPAREADC2 (MAF) | analog_in | single_source | |
| OEM-2-M | EGR valve | low_side_out | — | — | — | single_source | |
| OEM-2-N | EGR valve | low_side_out | — | — | — | single_source | |
| OEM-2-O | EGR valve | low_side_out | — | — | — | single_source | |
| OEM-2-P | EGR valve | low_side_out | — | — | — | single_source | |
| OEM-3-A | Power ground | ground | MICROSQUIRT-A-22 + MICROSQUIRT-A-23 | POWER GROUND + POWER GROUND | ground | single_source | |
| OEM-3-B | Power ground | ground | MICROSQUIRT-A-22 + MICROSQUIRT-A-23 | POWER GROUND + POWER GROUND | ground | single_source | |
| OEM-3-C | Power ground | ground | MICROSQUIRT-A-22 + MICROSQUIRT-A-23 | POWER GROUND + POWER GROUND | ground | single_source | |
| OEM-3-E | Throttle position (TPS) | analog_in | MICROSQUIRT-A-27 | TPS | analog_in | single_source | |
| OEM-3-F | Signal ground | sensor_ground | MICROSQUIRT-A-18 + MICROSQUIRT-A-19 + MICROSQUIRT-A-20 | Sensor Ground + Serial Ground + Sensor Ground | sensor_ground | single_source | |
| OEM-3-G | Ignition 1 (coils 1+4, wasted spark) | ignition_out | MICROSQUIRT-A-11 | SPK B (IGN2) | ignition_out | single_source | |
| OEM-3-H | Ignition 2 (coils 2+3, wasted spark) | ignition_out | MICROSQUIRT-A-12 | SPK A (IGN 1) | ignition_out | single_source | |
| OEM-3-I | Clutch switch | digital_in | — | — | — | single_source | |
| OEM-3-J | Rear O2 signal | lambda_nb_in | MICROSQUIRT-A-29 | SPAREADC | analog_in | single_source | |
| OEM-3-K | Fuel level | analog_in | — | — | — | single_source | |
| OEM-3-L | Evap purge solenoid | low_side_out | — | — | — | single_source | |
| OEM-3-M | ISC valve +14V feed | power_in | MICROSQUIRT-A-1 | +12V In | power_in | single_source | |
| OEM-3-N | Fuel pump relay | low_side_out | MICROSQUIRT-A-7 | FIDLE | low_side_out | single_source | |
| OEM-3-O | ISC valve low side | low_side_out | — | — | — | single_source | |
| OEM-3-Q | VICS solenoid (intake butterflies) | low_side_out | — | — | — | single_source | |
| OEM-3-S | EGR boost sensor | analog_in | — | — | — | single_source | |
| OEM-3-T | EGR boost solenoid | low_side_out | — | — | — | single_source | |
| OEM-3-U | Canister drain cut valve (CDCV) | low_side_out | — | — | — | single_source | |
| OEM-3-V | Rear O2 heater | low_side_out | — | — | — | single_source | |
| OEM-3-W | Injector 1 | injector_out | MICROSQUIRT-A-9 | INJ 1 | injector_out | single_source | |
| OEM-3-X | Injector 2 | injector_out | MICROSQUIRT-A-10 | INJ 2 | injector_out | single_source | |
| OEM-3-Y | Injector 3 | injector_out | — | — | — | single_source | |
| OEM-3-Z | Injector 4 | injector_out | — | — | — | single_source |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-1-B | SP-14V-1 | 0.85 | no route | ECU power +14V (main relay) | — | |
| W2 | OEM-3-M | SP-14V-1 | 0.85 | no route | ISC valve +14V feed | — | |
| W3 | SP-14V-1 | MICROSQUIRT-A-1 | 0.85 | no route | +12V In | — | |
| W4 | OEM-3-A | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W5 | OEM-3-B | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W6 | OEM-3-C | SP-GND-1 | 0.85 | no route | Power 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-F | SP-0V-1 | 0.5 | no route | Signal ground | — | |
| W10 | SP-0V-1 | MICROSQUIRT-A-18 | 0.5 | no route | Sensor Ground | — | |
| W11 | SP-0V-1 | MICROSQUIRT-A-19 | 0.5 | no route | Serial Ground | — | |
| W12 | SP-0V-1 | MICROSQUIRT-A-20 | 0.5 | no route | Sensor Ground | — | |
| W13 | OEM-2-I | MICROSQUIRT-A-28 | 0.5 | no route | +5V sensor supply | — | |
| W14 | OEM-2-J | MICROSQUIRT-A-32 | 0.5 | no route | Crank position (CKP) | — | |
| W15 | OEM-2-H | MICROSQUIRT-A-4 | 0.5 | no route | Cam position (CMP) | — | |
| W16 | OEM-3-G | MICROSQUIRT-A-11 | 0.5 | no route | Ignition 1 (coils 1+4, wasted spark) | — | |
| W17 | OEM-3-H | MICROSQUIRT-A-12 | 0.5 | no route | Ignition 2 (coils 2+3, wasted spark) | — | |
| W18 | OEM-3-W | MICROSQUIRT-A-9 | 0.5 | no route | Injector 1 | — | |
| W19 | OEM-3-X | MICROSQUIRT-A-10 | 0.5 | no route | Injector 2 | — | |
| W20 | OEM-1-I | MICROSQUIRT-A-8 | 0.5 | no route | Condenser fan relay | — | |
| W21 | OEM-1-R | MICROSQUIRT-A-16 | 0.5 | no route | Cooling fan relay | — | |
| W22 | OEM-1-S | MICROSQUIRT-A-17 | 0.5 | no route | A/C clutch relay | — | |
| W23 | OEM-3-N | MICROSQUIRT-A-7 | 0.5 | no route | Fuel pump relay | — | |
| W24 | OEM-2-K | MICROSQUIRT-A-35 | 0.5 | no route | Tachometer output | — | |
| W25 | OEM-2-L | MICROSQUIRT-A-5 | 0.5 | no route | Mass air flow (MAF) | — | |
| W26 | OEM-3-E | MICROSQUIRT-A-27 | 0.5 | no route | Throttle position (TPS) | — | |
| W27 | OEM-2-C | MICROSQUIRT-A-34 | 0.5 | no route | Front O2 signal | — | |
| W28 | OEM-3-J | MICROSQUIRT-A-29 | 0.5 | no route | Rear O2 signal | — | |
| W29 | OEM-2-E | MICROSQUIRT-A-25 | 0.5 | no route | Coolant temperature (ECT) | — | |
| W30 | OEM-2-B | MICROSQUIRT-A-26 | 0.5 | no route | Intake air temperature (IAT) | — | |
| W31 | OEM-2-D | MICROSQUIRT-A-30 | 0.5 | no route | Vehicle speed | — | |
| W32 | OEM-1-F | MICROSQUIRT-A-31 | 0.5 | no route | Brake switch | — | |
| W33 | OEM-1-G | MICROSQUIRT-A-6 | 0.5 | no route | Power steering pressure switch | — |
Bill of materials
| Category | Part number | Manufacturer | Description | Qty | Unit |
|---|---|---|---|---|---|
| connector | 174514-6 | TE | AMP Multilock .040/.070 hybrid 16-pin female harness plug (Miata NB1 ECU) | 1.000 | ea |
| connector | 174515-6 | TE | AMP Multilock .040/.070 hybrid 22-pin female harness plug (Miata NA/NB ECU) | 1.000 | ea |
| connector | 174516-6 | TE | AMP Multilock .040/.070 hybrid 26-pin female harness plug (Miata NA/NB ECU) | 1.000 | ea |
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 | REQUIRED_UNMAPPED | OEM-3-Y | Required OEM function "Injector 3" (injector_out) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-3-Z | Required OEM function "Injector 4" (injector_out) is not connected to the new ECU. |
| info | UNMAPPED | OEM | 21 optional OEM pins are not mapped: OEM-1-E Malfunction indicator lamp (MIL); OEM-1-O Alternator control; OEM-1-P A/C request; OEM-1-Q Charge lamp; OEM-1-U Front O2 heater; OEM-1-V Neutral switch; OEM-2-A Fuel tank pressure; OEM-2-F Knock sensor; OEM-2-M EGR valve; OEM-2-N EGR valve; OEM-2-O EGR valve; OEM-2-P EGR valve; OEM-3-I Clutch switch; OEM-3-K Fuel level; OEM-3-L Evap purge solenoid; OEM-3-O ISC valve low side; OEM-3-Q VICS solenoid (intake butterflies); OEM-3-S EGR boost sensor; OEM-3-T EGR boost solenoid; OEM-3-U Canister drain cut valve (CDCV); OEM-3-V Rear O2 heater |
Accepted (1)
| Code | Subject | Reason | By |
|---|---|---|---|
| REQUIRED_UNMAPPED | OEM-1-A | 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 2026-10-06. Review every wire against both manuals before building. Open items: - OEM-3 Y: Injector 3: no free injector output on AMP EFI Microsquirt - OEM-3 Z: Injector 4: no free injector output on AMP EFI Microsquirt Not wired: - OEM-1 A: Constant +12V: AMP EFI Microsquirt has no battery-constant input; not needed - OEM-2 F: Knock sensor: no free knock input on AMP EFI Microsquirt - OEM-1 U: Front O2 heater: no free heater_low_side/low_side/ls_hs/hbridge on AMP EFI Microsquirt - OEM-3 V: Rear O2 heater: no free heater_low_side/low_side/ls_hs/hbridge on AMP EFI Microsquirt - OEM-3 O: ISC valve low side: no free low_side/ls_hs/injector/hbridge rated ≥ 1.0 A on AMP EFI Microsquirt - OEM-1 E: Malfunction indicator lamp (MIL): no free low_side/ls_hs/injector/hbridge on AMP EFI Microsquirt - OEM-1 O: Alternator control: no free low_side/ls_hs/injector/hbridge on AMP EFI Microsquirt - OEM-1 Q: Charge lamp: no free low_side/ls_hs/injector/hbridge on AMP EFI Microsquirt - OEM-2 M: EGR valve: no free low_side/ls_hs/injector/hbridge on AMP EFI Microsquirt - OEM-2 N: EGR valve: no free low_side/ls_hs/injector/hbridge on AMP EFI Microsquirt - OEM-2 O: EGR valve: no free low_side/ls_hs/injector/hbridge on AMP EFI Microsquirt - OEM-2 P: EGR valve: no free low_side/ls_hs/injector/hbridge on AMP EFI Microsquirt - OEM-3 L: Evap purge solenoid: no free low_side/ls_hs/injector/hbridge on AMP EFI Microsquirt - OEM-3 Q: VICS solenoid (intake butterflies): no free low_side/ls_hs/injector/hbridge on AMP EFI Microsquirt - OEM-3 T: EGR boost solenoid: no free low_side/ls_hs/injector/hbridge on AMP EFI Microsquirt - OEM-3 U: Canister drain cut valve (CDCV): no free low_side/ls_hs/injector/hbridge on AMP EFI Microsquirt - OEM-2 A: Fuel tank pressure: no free analog_0_5 on AMP EFI Microsquirt - OEM-3 K: Fuel level: no free analog_0_5 on AMP EFI Microsquirt - OEM-3 S: EGR boost sensor: no free analog_0_5 on AMP EFI Microsquirt - OEM-1 P: A/C request: no free switch_in/frequency_in/analog_0_5 on AMP EFI Microsquirt - OEM-1 V: Neutral switch: no free switch_in/frequency_in/analog_0_5 on AMP EFI Microsquirt - OEM-3 I: Clutch 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 | Link G4X MX5NB1X install manual (NB1 1999-00) | https://linkecu.com/documentation/MX5XNB1.pdf | archive | 2026-10-05 | 2e36c91270cc |
| 4 | vendor_doc | MSExtra: Microsquirt hardware 3.4 | http://www.msextra.com/doc/pdf/Microsquirt_Hardware-3.4.pdf | archive | 2026-10-05 | ad920d9160de |