MX-5 Miata NB1 1999-00 (BP-4W) → FuelTech FT450 (auto)
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.
Install modifications
Steps on the car itself, outside the harness. Every harness for this car inherits them.
- Re-route the pressure-sensor vacuum hose to the intake manifoldrequired
Re-route the pressure sensor's (Mazda "EGR boost sensor", pin 3S) vacuum hose directly to the intake manifold, bypassing the EGR boost solenoid. The stock ECU multiplexes baro + MAP through that solenoid: with it off the sensor reads atmosphere, with it energized it reads manifold (2000 FSM P0107/P0108). After re-routing the sensor reads MAP only, so the standalone needs its own barometric source — its onboard baro sensor if fitted, or a separate baro sensor on a spare analog input. (Alternative, not recommended: keep the hose stock and have the ECU energize the solenoid permanently via a low-side output switched with ignition; this costs an output.)
Why: With the solenoid off (its default) the sensor reads atmospheric pressure, not manifold pressure, so a standalone that uses this sensor as its MAP input would read the wrong value.
Where: EGR boost solenoid and the pressure sensor's vacuum hose (sensor signal 3S).
Source: 2000 Mazda MX-5 Miata factory service manual — engine self-diagnostics (DTC P0106/P0107/P0108)
| 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 | 30 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 | FT450-A-A13 | 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 | FT450-A-A7 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | OEM-3-F | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | SP-0V-1 | FT450-A-A12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | OEM-2-I | FT450-A-A14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | OEM-2-J | FT450-A-A18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | SP-0V-1 | FT450-A-A18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-2-H | FT450-A-A17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-3-G | FT450-A-A8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | OEM-3-H | FT450-A-A9 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | OEM-3-W | FT450-A-A1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-3-X | FT450-A-A2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-3-Y | FT450-A-A1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-3-Z | FT450-A-A2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-2-L | FT450-A-A20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-3-E | FT450-A-A21 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-2-E | FT450-A-A24 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-1-I | FT450-A-A6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-1-R | FT450-A-A3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-1-S | FT450-A-A4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-3-N | FT450-A-A5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-3-S | FT450-A-A23 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-2-C | FT450-A-A22 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-3-J | FT450-A-A25 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-2-B | FT450-A-A26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ |
Bench test (before first power-up)
Pre-power install steps (make these cuts/modifications on the car first, then verify the checks below): Re-route the pressure-sensor vacuum hose to the intake manifold.
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 | FT450-A-A13 | FT450-A-A12 | open (OL) | +12 V supply must not touch sensor ground | |
| 2 | FT450-A-A13 | FT450-A-A7 | open (OL) | +12 V supply must not touch power ground | |
| 3 | FT450-A-A14 | FT450-A-A12 | open (OL) | 5 V sensor reference must not touch sensor ground | |
| 4 | FT450-A-A14 | FT450-A-A7 | open (OL) | 5 V sensor reference must not touch power ground | |
| 5 | FT450-A-A13 | FT450-A-A14 | open (OL) | +12 V supply must not touch 5 V sensor reference |
If any reading doesn't match, stop and get help before powering up.
Revisions
| Rev | Label | By | Date |
|---|---|---|---|
| No revisions yet. | |||
Schematic
Connectors
FT450-A
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A1 | Injector 1 (Bank A) | — | W16 | — | 0.5 | OEM-3-W | — | — | — |
| A1 | Injector 1 (Bank A) | — | W18 | — | 0.5 | OEM-3-Y | — | — | — |
| A10 | Ignition 3 | — | — | — | — | — | — | — | — |
| A11 | Ignition 4 | — | — | — | — | — | — | — | — |
| A12 | Signal ground | — | W9 | — | 0.5 | SP-0V-1 | — | — | — |
| A13 | +12V switched | — | W3 | — | 0.85 | SP-14V-1 | — | — | — |
| A14 | +5V sensor supply | — | W10 | — | 0.5 | OEM-2-I | — | — | — |
| A15 | CAN A LOW | — | — | — | — | — | — | — | — |
| A16 | CAN A HIGH | — | — | — | — | — | — | — | — |
| A17 | Phase input (cam) | — | W13 | — | 0.5 | OEM-2-H | — | — | — |
| A18 | RPM reference (crank -) | — | W11 | — | 0.5 | OEM-2-J | — | — | — |
| A18 | RPM reference (crank -) | — | W12 | — | 0.5 | SP-0V-1 | — | — | — |
| A19 | RPM signal (crank +) | — | — | — | — | — | — | — | — |
| A2 | Injector 2 (Bank A) | — | W17 | — | 0.5 | OEM-3-X | — | — | — |
| A2 | Injector 2 (Bank A) | — | W19 | — | 0.5 | OEM-3-Z | — | — | — |
| A20 | White input 1 | — | W20 | — | 0.5 | OEM-2-L | — | — | — |
| A21 | White input 2 | — | W21 | — | 0.5 | OEM-3-E | — | — | — |
| A22 | White input 3 (TPS) | — | W28 | — | 0.5 | OEM-2-C | — | — | — |
| A23 | White input 4 (oil pressure) | — | W27 | — | 0.5 | OEM-3-S | — | — | — |
| A24 | White input 5 (water temp) | — | W22 | — | 0.5 | OEM-2-E | — | — | — |
| A25 | White input 6 (fuel pressure) | — | W29 | — | 0.5 | OEM-3-J | — | — | — |
| A26 | White input 7 (air temp) | — | W30 | — | 0.5 | OEM-2-B | — | — | — |
| A3 | Aux 1 | — | W24 | — | 0.5 | OEM-1-R | — | — | — |
| A4 | Aux 2 | — | W25 | — | 0.5 | OEM-1-S | — | — | — |
| A5 | Aux 3 | — | W26 | — | 0.5 | OEM-3-N | — | — | — |
| A6 | Aux 4 (fuel pump / relays) | — | W23 | — | 0.5 | OEM-1-I | — | — | — |
| A7 | Power ground | — | W7 | — | 0.85 | SP-GND-1 | — | — | — |
| A8 | Ignition 1 | — | W14 | — | 0.5 | OEM-3-G | — | — | — |
| A9 | Ignition 2 | — | W15 | — | 0.5 | OEM-3-H | — | — | — |
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 | — | — | — | — | — | — | — | — |
| G | Power steering pressure switch | — | — | — | — | — | — | — | — |
| I | Condenser fan relay | — | W23 | — | 0.5 | FT450-A-A6 | — | — | — |
| O | Alternator control | — | — | — | — | — | — | — | — |
| P | A/C request | — | — | — | — | — | — | — | — |
| Q | Charge lamp | — | — | — | — | — | — | — | — |
| R | Cooling fan relay | — | W24 | — | 0.5 | FT450-A-A3 | — | — | — |
| S | A/C clutch relay | — | W25 | — | 0.5 | FT450-A-A4 | — | — | — |
| 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 | FT450-A-A26 | — | — | — |
| C | Front O2 signal | — | W28 | — | 0.5 | FT450-A-A22 | — | — | — |
| D | Vehicle speed | — | — | — | — | — | — | — | — |
| E | Coolant temperature (ECT) | — | W22 | — | 0.5 | FT450-A-A24 | — | — | — |
| F | Knock sensor | — | — | — | — | — | — | — | — |
| H | Cam position (CMP) | — | W13 | — | 0.5 | FT450-A-A17 | — | — | — |
| I | +5V sensor supply | — | W10 | — | 0.5 | FT450-A-A14 | — | — | — |
| J | Crank position (CKP) | — | W11 | — | 0.5 | FT450-A-A18 | — | — | — |
| K | Tachometer output | — | — | — | — | — | — | — | — |
| L | Mass air flow (MAF) | — | W20 | — | 0.5 | FT450-A-A20 | — | — | — |
| 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) | — | W21 | — | 0.5 | FT450-A-A21 | — | — | — |
| F | Signal ground | — | W8 | — | 0.5 | SP-0V-1 | — | — | — |
| G | Ignition 1 (coils 1+4, wasted spark) | — | W14 | — | 0.5 | FT450-A-A8 | — | — | — |
| H | Ignition 2 (coils 2+3, wasted spark) | — | W15 | — | 0.5 | FT450-A-A9 | — | — | — |
| I | Clutch switch | — | — | — | — | — | — | — | — |
| J | Rear O2 signal | — | W29 | — | 0.5 | FT450-A-A25 | — | — | — |
| K | Fuel level | — | — | — | — | — | — | — | — |
| L | Evap purge solenoid | — | — | — | — | — | — | — | — |
| M | ISC valve +14V feed | — | W2 | — | 0.85 | SP-14V-1 | — | — | — |
| N | Fuel pump relay | — | W26 | — | 0.5 | FT450-A-A5 | — | — | — |
| O | ISC valve low side | — | — | — | — | — | — | — | — |
| Q | VICS solenoid (intake butterflies) | — | — | — | — | — | — | — | — |
| S | Pressure sensor (Mazda: EGR boost sensor) | — | W27 | — | 0.5 | FT450-A-A23 | — | — | — |
| T | EGR boost solenoid | — | — | — | — | — | — | — | — |
| U | Canister drain cut valve (CDCV) | — | — | — | — | — | — | — | — |
| V | Rear O2 heater | — | — | — | — | — | — | — | — |
| W | Injector 1 | — | W16 | — | 0.5 | FT450-A-A1 | — | — | — |
| X | Injector 2 | — | W17 | — | 0.5 | FT450-A-A2 | — | — | — |
| Y | Injector 3 | — | W18 | — | 0.5 | FT450-A-A1 | — | — | — |
| Z | Injector 4 | — | W19 | — | 0.5 | FT450-A-A2 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W8 | — | 0.5 | OEM-3-F | — | — | — |
| 1 | — | — | W9 | — | 0.5 | FT450-A-A12 | — | — | — |
| 1 | — | — | W12 | — | 0.5 | FT450-A-A18 | — | — | — |
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 | FT450-A-A13 | — | — | — |
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 | FT450-A-A7 | — | — | — |
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 | FT450-A-A13 | +12V switched | power_in | single_source | |
| OEM-1-E | Malfunction indicator lamp (MIL) | low_side_out | — | — | — | single_source | |
| OEM-1-F | Brake switch | digital_in | — | — | — | single_source | |
| OEM-1-G | Power steering pressure switch | digital_in | — | — | — | single_source | |
| OEM-1-I | Condenser fan relay | low_side_out | FT450-A-A6 | Aux 4 (fuel pump / relays) | 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 | FT450-A-A3 | Aux 1 | low_side_out | single_source | |
| OEM-1-S | A/C clutch relay | low_side_out | FT450-A-A4 | Aux 2 | 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 | FT450-A-A26 | White input 7 (air temp) | temp_in | single_source | |
| OEM-2-C | Front O2 signal | lambda_nb_in | FT450-A-A22 | White input 3 (TPS) | analog_in | single_source | |
| OEM-2-D | Vehicle speed | digital_in | — | — | — | single_source | |
| OEM-2-E | Coolant temperature (ECT) | temp_in | FT450-A-A24 | White input 5 (water temp) | temp_in | single_source | |
| OEM-2-F | Knock sensor | knock_in | — | — | — | single_source | |
| OEM-2-H | Cam position (CMP) | trigger_in | FT450-A-A17 | Phase input (cam) | trigger_in | single_source | |
| OEM-2-I | +5V sensor supply | vref | FT450-A-A14 | +5V sensor supply | vref | single_source | |
| OEM-2-J | Crank position (CKP) | trigger_in | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | single_source | |
| OEM-2-K | Tachometer output | tacho_out | — | — | — | single_source | |
| OEM-2-L | Mass air flow (MAF) | analog_in | FT450-A-A20 | White input 1 | 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 | FT450-A-A7 | Power ground | ground | single_source | |
| OEM-3-B | Power ground | ground | FT450-A-A7 | Power ground | ground | single_source | |
| OEM-3-C | Power ground | ground | FT450-A-A7 | Power ground | ground | single_source | |
| OEM-3-E | Throttle position (TPS) | analog_in | FT450-A-A21 | White input 2 | analog_in | single_source | |
| OEM-3-F | Signal ground | sensor_ground | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | single_source | |
| OEM-3-G | Ignition 1 (coils 1+4, wasted spark) | ignition_out | FT450-A-A8 | Ignition 1 | ignition_out | single_source | |
| OEM-3-H | Ignition 2 (coils 2+3, wasted spark) | ignition_out | FT450-A-A9 | Ignition 2 | ignition_out | single_source | |
| OEM-3-I | Clutch switch | digital_in | — | — | — | single_source | |
| OEM-3-J | Rear O2 signal | lambda_nb_in | FT450-A-A25 | White input 6 (fuel pressure) | 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 | FT450-A-A13 | +12V switched | power_in | single_source | |
| OEM-3-N | Fuel pump relay | low_side_out | FT450-A-A5 | Aux 3 | 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 | Pressure sensor (Mazda: EGR boost sensor) | analog_in | FT450-A-A23 | White input 4 (oil pressure) | analog_in | single_source | |
| OEM-3-T | EGR boost solenoid | — | — | — | — | 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 | FT450-A-A1 | Injector 1 (Bank A) | injector_out | single_source | |
| OEM-3-X | Injector 2 | injector_out | FT450-A-A2 | Injector 2 (Bank A) | injector_out | single_source | |
| OEM-3-Y | Injector 3 | injector_out | FT450-A-A1 | Injector 1 (Bank A) | injector_out | single_source | |
| OEM-3-Z | Injector 4 | injector_out | FT450-A-A2 | Injector 2 (Bank A) | 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 | FT450-A-A13 | 0.85 | no route | +12V switched | — | |
| 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 | FT450-A-A7 | 0.85 | no route | Power ground | — | |
| W8 | OEM-3-F | SP-0V-1 | 0.5 | no route | Signal ground | — | |
| W9 | SP-0V-1 | FT450-A-A12 | 0.5 | no route | Signal ground | — | |
| W10 | OEM-2-I | FT450-A-A14 | 0.5 | no route | +5V sensor supply | — | |
| W11 | OEM-2-J | FT450-A-A18 | 0.5 | no route | Crank position (CKP) | — | |
| W12 | SP-0V-1 | FT450-A-A18 | 0.5 | no route | RPM reference (crank -) | — | |
| W13 | OEM-2-H | FT450-A-A17 | 0.5 | no route | Cam position (CMP) | — | |
| W14 | OEM-3-G | FT450-A-A8 | 0.5 | no route | Ignition 1 (coils 1+4, wasted spark) | — | |
| W15 | OEM-3-H | FT450-A-A9 | 0.5 | no route | Ignition 2 (coils 2+3, wasted spark) | — | |
| W16 | OEM-3-W | FT450-A-A1 | 0.5 | no route | Injector 1 | — | |
| W17 | OEM-3-X | FT450-A-A2 | 0.5 | no route | Injector 2 | — | |
| W18 | OEM-3-Y | FT450-A-A1 | 0.5 | no route | Injector 3 | — | |
| W19 | OEM-3-Z | FT450-A-A2 | 0.5 | no route | Injector 4 | — | |
| W20 | OEM-2-L | FT450-A-A20 | 0.5 | no route | Mass air flow (MAF) | — | |
| W21 | OEM-3-E | FT450-A-A21 | 0.5 | no route | Throttle position (TPS) | — | |
| W22 | OEM-2-E | FT450-A-A24 | 0.5 | no route | Coolant temperature (ECT) | — | |
| W23 | OEM-1-I | FT450-A-A6 | 0.5 | no route | Condenser fan relay | — | |
| W24 | OEM-1-R | FT450-A-A3 | 0.5 | no route | Cooling fan relay | — | |
| W25 | OEM-1-S | FT450-A-A4 | 0.5 | no route | A/C clutch relay | — | |
| W26 | OEM-3-N | FT450-A-A5 | 0.5 | no route | Fuel pump relay | — | |
| W27 | OEM-3-S | FT450-A-A23 | 0.5 | no route | Pressure sensor (Mazda: EGR boost sensor) | — | |
| W28 | OEM-2-C | FT450-A-A22 | 0.5 | no route | Front O2 signal | — | |
| W29 | OEM-3-J | FT450-A-A25 | 0.5 | no route | Rear O2 signal | — | |
| W30 | OEM-2-B | FT450-A-A26 | 0.5 | no route | Intake air temperature (IAT) | — |
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 (8)
| Severity | Code | Subject | Message |
|---|---|---|---|
| error | NET_MERGED | FT450-A-A1 + OEM-3-W + OEM-3-Y | 2 different OEM functions share one net: OEM-3-W Injector 1; OEM-3-Y Injector 3 |
| error | NET_MERGED | FT450-A-A2 + OEM-3-X + OEM-3-Z | 2 different OEM functions share one net: OEM-3-X Injector 2; OEM-3-Z Injector 4 |
| warn | LOAD_UNKNOWN | FT450-A-A3 | FT450-A-A3 "Aux 1" drives OEM-1-R Cooling fan relay (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | LOAD_UNKNOWN | FT450-A-A4 | FT450-A-A4 "Aux 2" drives OEM-1-S A/C clutch relay (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | LOAD_UNKNOWN | FT450-A-A5 | FT450-A-A5 "Aux 3" drives OEM-3-N Fuel pump relay (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | LOAD_UNKNOWN | FT450-A-A6 | FT450-A-A6 "Aux 4 (fuel pump / relays)" drives OEM-1-I Condenser fan relay (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| info | NET_FAMILY | OEM-2-J ↔ OEM-3-F | OEM-2-J "Crank position (CKP)" [trigger_in] is wired to OEM-3-F "Signal ground" [sensor_ground]. Trigger return tied to sensor/trigger ground: correct for single-ended trigger inputs. |
| info | UNMAPPED | OEM | 24 optional OEM pins are not mapped: OEM-1-E Malfunction indicator lamp (MIL); OEM-1-F Brake switch; OEM-1-G Power steering pressure switch; 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-D Vehicle speed; OEM-2-F Knock sensor; OEM-2-K Tachometer output; 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-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 2026-10-11. Review every wire against both manuals before building. Not wired: - OEM-1 A: Constant +12V: FuelTech FT450 has no battery-constant input; not needed - OEM-2 F: Knock sensor: no free knock input on FuelTech FT450 - OEM-1 U: Front O2 heater: no free heater_low_side/low_side/relay_control/ls_hs/injector on FuelTech FT450 - OEM-3 V: Rear O2 heater: no free heater_low_side/low_side/relay_control/ls_hs/injector on FuelTech FT450 - OEM-3 O: ISC valve low side: no free low_side/relay_control/heater_low_side/ls_hs/injector rated ≥ 1.0 A on FuelTech FT450 - OEM-1 E: Malfunction indicator lamp (MIL): no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-1 O: Alternator control: no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-1 Q: Charge lamp: no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-2 M: EGR valve: no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-2 N: EGR valve: no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-2 O: EGR valve: no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-2 P: EGR valve: no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-3 L: Evap purge solenoid: no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-3 Q: VICS solenoid (intake butterflies): no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-3 U: Canister drain cut valve (CDCV): no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-2 K: Tachometer output: no free tacho/frequency_out/low_side/ls_hs on FuelTech FT450 - OEM-2 A: Fuel tank pressure: no free analog_0_5 on FuelTech FT450 - OEM-3 K: Fuel level: no free analog_0_5 on FuelTech FT450 - OEM-2 D: Vehicle speed: no free frequency_in/switch_in on FuelTech FT450 - OEM-1 F: Brake switch: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-1 G: Power steering pressure switch: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-1 P: A/C request: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-1 V: Neutral switch: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-3 I: Clutch switch: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-3 T: EGR boost solenoid: not classified in the library; wire by hand
Sources
| Reliability | Kind | Title | URL | Archive | Captured | SHA-256 |
|---|---|---|---|---|---|---|
| 4 | vendor_doc | FuelTech FT450/FT550 ready harness manual (4 & 6 cylinder) — FT450 Connector A pinout | http://ftmanager.fueltech.com.br/downloads/manual/Portugues/Chicote_pronto_FT450-FT550.pdf | — | — | — |
| 4 | vendor_doc | Link G4X MX5NB1X install manual (NB1 1999-00) | https://linkecu.com/documentation/MX5XNB1.pdf | archive | 2026-10-05 | 2e36c91270cc |
| 2 | expert_report | Justin Barrera — Miata NA/NB wiring corrections | — | — | — | — |