MX-5 Miata NB2 2001-05 (BP-Z3, VVT; excludes Mazdaspeed) → 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 4AE) 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. 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 4AE).
Source: Justin Barrera — Miata NA/NB wiring corrections
| 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 | 31 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-2-P | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | OEM-4-AF | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | OEM-4-D | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | SP-14V-1 | FT450-A-A13 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | OEM-3-A | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | OEM-3-B | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | OEM-4-A | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | SP-GND-1 | FT450-A-A7 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | OEM-4-O | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | SP-0V-1 | FT450-A-A12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | OEM-4-L | FT450-A-A14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | OEM-3-Y | FT450-A-A18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | SP-0V-1 | FT450-A-A18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-3-V | FT450-A-A17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | OEM-3-F | FT450-A-A8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | OEM-3-I | FT450-A-A9 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-2-A | FT450-A-A1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-2-D | FT450-A-A2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-2-G | FT450-A-A1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-2-J | FT450-A-A2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-2-B | FT450-A-A6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-2-C | FT450-A-A3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-2-K | FT450-A-A4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-2-M | FT450-A-A5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-4-X | FT450-A-A20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-4-AE | FT450-A-A23 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-4-V | FT450-A-A21 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-4-AA | FT450-A-A22 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-4-W | FT450-A-A25 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-4-P | FT450-A-A24 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W31 | OEM-4-N | 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-A12 | FT450-A-A14 | open (OL) | sensor ground must not touch 5 V sensor reference | |
| 4 | FT450-A-A13 | FT450-A-A14 | open (OL) | +12 V supply must not touch 5 V sensor reference | |
| 5 | FT450-A-A7 | FT450-A-A14 | open (OL) | power ground 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) | — | W17 | — | 0.5 | OEM-2-A | — | — | — |
| A1 | Injector 1 (Bank A) | — | W19 | — | 0.5 | OEM-2-G | — | — | — |
| A10 | Ignition 3 | — | — | — | — | — | — | — | — |
| A11 | Ignition 4 | — | — | — | — | — | — | — | — |
| A12 | Signal ground | — | W10 | — | 0.5 | SP-0V-1 | — | — | — |
| A13 | +12V switched | — | W4 | — | 0.85 | SP-14V-1 | — | — | — |
| A14 | +5V sensor supply | — | W11 | — | 0.5 | OEM-4-L | — | — | — |
| A15 | CAN A LOW | — | — | — | — | — | — | — | — |
| A16 | CAN A HIGH | — | — | — | — | — | — | — | — |
| A17 | Phase input (cam) | — | W14 | — | 0.5 | OEM-3-V | — | — | — |
| A18 | RPM reference (crank -) | — | W12 | — | 0.5 | OEM-3-Y | — | — | — |
| A18 | RPM reference (crank -) | — | W13 | — | 0.5 | SP-0V-1 | — | — | — |
| A19 | RPM signal (crank +) | — | — | — | — | — | — | — | — |
| A2 | Injector 2 (Bank A) | — | W18 | — | 0.5 | OEM-2-D | — | — | — |
| A2 | Injector 2 (Bank A) | — | W20 | — | 0.5 | OEM-2-J | — | — | — |
| A20 | White input 1 | — | W25 | — | 0.5 | OEM-4-X | — | — | — |
| A21 | White input 2 | — | W27 | — | 0.5 | OEM-4-V | — | — | — |
| A22 | White input 3 (TPS) | — | W28 | — | 0.5 | OEM-4-AA | — | — | — |
| A23 | White input 4 (oil pressure) | — | W26 | — | 0.5 | OEM-4-AE | — | — | — |
| A24 | White input 5 (water temp) | — | W30 | — | 0.5 | OEM-4-P | — | — | — |
| A25 | White input 6 (fuel pressure) | — | W29 | — | 0.5 | OEM-4-W | — | — | — |
| A26 | White input 7 (air temp) | — | W31 | — | 0.5 | OEM-4-N | — | — | — |
| A3 | Aux 1 | — | W22 | — | 0.5 | OEM-2-C | — | — | — |
| A4 | Aux 2 | — | W23 | — | 0.5 | OEM-2-K | — | — | — |
| A5 | Aux 3 | — | W24 | — | 0.5 | OEM-2-M | — | — | — |
| A6 | Aux 4 (fuel pump / relays) | — | W21 | — | 0.5 | OEM-2-B | — | — | — |
| A7 | Power ground | — | W8 | — | 0.85 | SP-GND-1 | — | — | — |
| A8 | Ignition 1 | — | W15 | — | 0.5 | OEM-3-F | — | — | — |
| A9 | Ignition 2 | — | W16 | — | 0.5 | OEM-3-I | — | — | — |
OEM-2
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Injector 1 | — | W17 | — | 0.5 | FT450-A-A1 | — | — | — |
| B | Cooling fan relay | — | W21 | — | 0.5 | FT450-A-A6 | — | — | — |
| C | Condenser fan relay | — | W22 | — | 0.5 | FT450-A-A3 | — | — | — |
| D | Injector 2 | — | W18 | — | 0.5 | FT450-A-A2 | — | — | — |
| E | EGR valve | — | — | — | — | — | — | — | — |
| F | EGR valve | — | — | — | — | — | — | — | — |
| G | Injector 3 | — | W19 | — | 0.5 | FT450-A-A1 | — | — | — |
| H | EGR valve | — | — | — | — | — | — | — | — |
| I | EGR valve | — | — | — | — | — | — | — | — |
| J | Injector 4 | — | W20 | — | 0.5 | FT450-A-A2 | — | — | — |
| K | A/C clutch relay | — | W23 | — | 0.5 | FT450-A-A4 | — | — | — |
| L | NC | — | — | — | — | — | — | — | — |
| M | Fuel pump relay | — | W24 | — | 0.5 | FT450-A-A5 | — | — | — |
| N | VTCS solenoid (intake butterflies) | — | — | — | — | — | — | — | — |
| O | Fuel pump relay (non-immobiliser) | — | — | — | — | — | — | — | — |
| P | ISC valve +14V feed | — | W1 | — | 0.85 | SP-14V-1 | — | — | — |
| Q | ISC valve low side | — | — | — | — | — | — | — | — |
| R | Malfunction indicator lamp (MIL) | — | — | — | — | — | — | — | — |
OEM-3
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Power ground | — | W5 | — | 0.85 | SP-GND-1 | — | — | — |
| B | Power ground | — | W6 | — | 0.85 | SP-GND-1 | — | — | — |
| C | Purge solenoid valve | — | — | — | — | — | — | — | — |
| D | EGR boost solenoid | — | — | — | — | — | — | — | — |
| E | NC | — | — | — | — | — | — | — | — |
| F | Ignition 1 (coils 1+4, wasted spark) | — | W15 | — | 0.5 | FT450-A-A8 | — | — | — |
| G | NC | — | — | — | — | — | — | — | — |
| H | Main relay | — | — | — | — | — | — | — | — |
| I | Ignition 2 (coils 2+3, wasted spark) | — | W16 | — | 0.5 | FT450-A-A9 | — | — | — |
| J | Front O2 heater | — | — | — | — | — | — | — | — |
| K | EVAP leak detection pump | — | — | — | — | — | — | — | — |
| L | NC | — | — | — | — | — | — | — | — |
| M | Alternator control | — | — | — | — | — | — | — | — |
| N | NC | — | — | — | — | — | — | — | — |
| O | Tachometer output | — | — | — | — | — | — | — | — |
| P | Rear O2 heater | — | — | — | — | — | — | — | — |
| Q | Data link connector (K-line) | — | — | — | — | — | — | — | — |
| R | NC | — | — | — | — | — | — | — | — |
| S | Immobiliser | — | — | — | — | — | — | — | — |
| T | Vehicle speed | — | — | — | — | — | — | — | — |
| U | Charge lamp | — | — | — | — | — | — | — | — |
| V | Cam position (CMP) | — | W14 | — | 0.5 | FT450-A-A17 | — | — | — |
| W | NC | — | — | — | — | — | — | — | — |
| X | NC | — | — | — | — | — | — | — | — |
| Y | Crank position (CKP) | — | W12 | — | 0.5 | FT450-A-A18 | — | — | — |
| Z | NC | — | — | — | — | — | — | — | — |
OEM-4
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Power ground | — | W7 | — | 0.85 | SP-GND-1 | — | — | — |
| AA | Rear O2 signal | — | W28 | — | 0.5 | FT450-A-A22 | — | — | — |
| AB | NC | — | — | — | — | — | — | — | — |
| AC | TCM (automatic only) | — | — | — | — | — | — | — | — |
| AD | Fuel level | — | — | — | — | — | — | — | — |
| AE | Pressure sensor (Mazda: EGR boost sensor) | — | W26 | — | 0.5 | FT450-A-A23 | — | — | — |
| AF | ECU power +14V (main relay) | — | W2 | — | 0.85 | SP-14V-1 | — | — | — |
| AG | Constant +12V | — | — | — | — | — | — | — | — |
| AH | EVAP leak detection pump solenoid valve | — | — | — | — | — | — | — | — |
| B | Brake switch | — | — | — | — | — | — | — | — |
| C | Power steering pressure switch | — | — | — | — | — | — | — | — |
| D | VVT oil-control solenoid +12V feed | — | W3 | — | 0.85 | SP-14V-1 | — | — | — |
| E | Diagnostic (DLC TEN) (NA) | — | — | — | — | — | — | — | — |
| F | A/C request | — | — | — | — | — | — | — | — |
| G | NC | — | — | — | — | — | — | — | — |
| H | Neutral switch | — | — | — | — | — | — | — | — |
| I | Clutch switch | — | — | — | — | — | — | — | — |
| J | VTCS vacuum switch | — | — | — | — | — | — | — | — |
| K | NC | — | — | — | — | — | — | — | — |
| L | +5V sensor supply | — | W11 | — | 0.5 | FT450-A-A14 | — | — | — |
| M | Knock sensor | — | — | — | — | — | — | — | — |
| N | Intake air temperature (IAT) | — | W31 | — | 0.5 | FT450-A-A26 | — | — | — |
| O | Signal ground | — | W9 | — | 0.5 | SP-0V-1 | — | — | — |
| P | Coolant temperature (ECT) | — | W30 | — | 0.5 | FT450-A-A24 | — | — | — |
| Q | NC | — | — | — | — | — | — | — | — |
| R | VVT oil-control solenoid (low-side control) | — | — | — | — | — | — | — | — |
| S | Ignition switch (IG1) sense | — | — | — | — | — | — | — | — |
| T | Generator output voltage (terminal P) | — | — | — | — | — | — | — | — |
| U | NC | — | — | — | — | — | — | — | — |
| V | Throttle position (TPS) | — | W27 | — | 0.5 | FT450-A-A21 | — | — | — |
| W | Front O2 signal | — | W29 | — | 0.5 | FT450-A-A25 | — | — | — |
| X | Mass air flow (MAF) | — | W25 | — | 0.5 | FT450-A-A20 | — | — | — |
| Y | NC | — | — | — | — | — | — | — | — |
| Z | TCM (automatic only) | — | — | — | — | — | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W9 | — | 0.5 | OEM-4-O | — | — | — |
| 1 | — | — | W10 | — | 0.5 | FT450-A-A12 | — | — | — |
| 1 | — | — | W13 | — | 0.5 | FT450-A-A18 | — | — | — |
SP-14V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W1 | — | 0.85 | OEM-2-P | — | — | — |
| 1 | — | — | W2 | — | 0.85 | OEM-4-AF | — | — | — |
| 1 | — | — | W3 | — | 0.85 | OEM-4-D | — | — | — |
| 1 | — | — | W4 | — | 0.85 | FT450-A-A13 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W5 | — | 0.85 | OEM-3-A | — | — | — |
| 1 | — | — | W6 | — | 0.85 | OEM-3-B | — | — | — |
| 1 | — | — | W7 | — | 0.85 | OEM-4-A | — | — | — |
| 1 | — | — | W8 | — | 0.85 | FT450-A-A7 | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| OEM-2-A | Injector 1 | injector_out | FT450-A-A1 | Injector 1 (Bank A) | injector_out | YB | single_source |
| OEM-2-B | Cooling fan relay | low_side_out | FT450-A-A6 | Aux 4 (fuel pump / relays) | low_side_out | RY | single_source |
| OEM-2-C | Condenser fan relay | low_side_out | FT450-A-A3 | Aux 1 | low_side_out | LW | single_source |
| OEM-2-D | Injector 2 | injector_out | FT450-A-A2 | Injector 2 (Bank A) | injector_out | VG | single_source |
| OEM-2-E | EGR valve | low_side_out | — | — | — | Lg | single_source |
| OEM-2-F | EGR valve | low_side_out | — | — | — | WG | single_source |
| OEM-2-G | Injector 3 | injector_out | FT450-A-A1 | Injector 1 (Bank A) | injector_out | YR | single_source |
| OEM-2-H | EGR valve | low_side_out | — | — | — | PB | single_source |
| OEM-2-I | EGR valve | low_side_out | — | — | — | P | single_source |
| OEM-2-J | Injector 4 | injector_out | FT450-A-A2 | Injector 2 (Bank A) | injector_out | YG | single_source |
| OEM-2-K | A/C clutch relay | low_side_out | FT450-A-A4 | Aux 2 | low_side_out | LB | single_source |
| OEM-2-L | NC | — | — | — | — | unverified | |
| OEM-2-M | Fuel pump relay | low_side_out | FT450-A-A5 | Aux 3 | low_side_out | RW | single_source |
| OEM-2-N | VTCS solenoid (intake butterflies) | low_side_out | — | — | — | BW | single_source |
| OEM-2-O | Fuel pump relay (non-immobiliser) | low_side_out | — | — | — | R | single_source |
| OEM-2-P | ISC valve +14V feed | power_in | FT450-A-A13 | +12V switched | power_in | Or | single_source |
| OEM-2-Q | ISC valve low side | low_side_out | — | — | — | VR | single_source |
| OEM-2-R | Malfunction indicator lamp (MIL) | low_side_out | — | — | — | WL | single_source |
| OEM-3-A | Power ground | ground | FT450-A-A7 | Power ground | ground | B | single_source |
| OEM-3-B | Power ground | ground | FT450-A-A7 | Power ground | ground | BR | single_source |
| OEM-3-C | Purge solenoid valve | low_side_out | — | — | — | GY | single_source |
| OEM-3-D | EGR boost solenoid | — | — | — | — | GyB | single_source |
| OEM-3-E | NC | — | — | — | — | unverified | |
| OEM-3-F | Ignition 1 (coils 1+4, wasted spark) | ignition_out | FT450-A-A8 | Ignition 1 | ignition_out | BrW | single_source |
| OEM-3-G | NC | — | — | — | — | unverified | |
| OEM-3-H | Main relay | low_side_out | — | — | — | LOr | single_source |
| OEM-3-I | Ignition 2 (coils 2+3, wasted spark) | ignition_out | FT450-A-A9 | Ignition 2 | ignition_out | BY | single_source |
| OEM-3-J | Front O2 heater | low_side_out | — | — | — | BOr | single_source |
| OEM-3-K | EVAP leak detection pump | low_side_out | — | — | — | YB | single_source |
| OEM-3-L | NC | — | — | — | — | unverified | |
| OEM-3-M | Alternator control | low_side_out | — | — | — | GyR | single_source |
| OEM-3-N | NC | — | — | — | — | unverified | |
| OEM-3-O | Tachometer output | tacho_out | — | — | — | GOr | single_source |
| OEM-3-P | Rear O2 heater | low_side_out | — | — | — | WB | single_source |
| OEM-3-Q | Data link connector (K-line) | serial | — | — | — | GW | single_source |
| OEM-3-R | NC | — | — | — | — | unverified | |
| OEM-3-S | Immobiliser | digital_in | — | — | — | RB | single_source |
| OEM-3-T | Vehicle speed | digital_in | — | — | — | GR | single_source |
| OEM-3-U | Charge lamp | low_side_out | — | — | — | BrR | single_source |
| OEM-3-V | Cam position (CMP) | trigger_in | FT450-A-A17 | Phase input (cam) | trigger_in | GyL | single_source |
| OEM-3-W | NC | — | — | — | — | unverified | |
| OEM-3-X | NC | — | — | — | — | unverified | |
| OEM-3-Y | Crank position (CKP) | trigger_in | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | VW | single_source |
| OEM-3-Z | NC | — | — | — | — | unverified | |
| OEM-4-A | Power ground | ground | FT450-A-A7 | Power ground | ground | BL | single_source |
| OEM-4-AA | Rear O2 signal | lambda_nb_in | FT450-A-A22 | White input 3 (TPS) | analog_in | R | single_source |
| OEM-4-AB | NC | — | — | — | — | unverified | |
| OEM-4-AC | TCM (automatic only) | — | — | — | — | VG | single_source |
| OEM-4-AD | Fuel level | analog_in | — | — | — | BrB | single_source |
| OEM-4-AE | Pressure sensor (Mazda: EGR boost sensor) | analog_in | FT450-A-A23 | White input 4 (oil pressure) | analog_in | LY | corroborated |
| OEM-4-AF | ECU power +14V (main relay) | power_in | FT450-A-A13 | +12V switched | power_in | WR | single_source |
| OEM-4-AG | Constant +12V | power_in | — | — | — | LR | single_source |
| OEM-4-AH | EVAP leak detection pump solenoid valve | low_side_out | — | — | — | RG | single_source |
| OEM-4-B | Brake switch | digital_in | — | — | — | G | single_source |
| OEM-4-C | Power steering pressure switch | digital_in | — | — | — | Br | single_source |
| OEM-4-D | VVT oil-control solenoid +12V feed | power_in | FT450-A-A13 | +12V switched | power_in | Y | single_source |
| OEM-4-E | Diagnostic (DLC TEN) (NA) | serial | — | — | — | LY | single_source |
| OEM-4-F | A/C request | digital_in | — | — | — | LgB | single_source |
| OEM-4-G | NC | — | — | — | — | unverified | |
| OEM-4-H | Neutral switch | digital_in | — | — | — | V | single_source |
| OEM-4-I | Clutch switch | digital_in | — | — | — | WG | single_source |
| OEM-4-J | VTCS vacuum switch | digital_in | — | — | — | Or | single_source |
| OEM-4-K | NC | — | — | — | — | unverified | |
| OEM-4-L | +5V sensor supply | vref | FT450-A-A14 | +5V sensor supply | vref | LgR | single_source |
| OEM-4-M | Knock sensor | knock_in | — | — | — | W | single_source |
| OEM-4-N | Intake air temperature (IAT) | temp_in | FT450-A-A26 | White input 7 (air temp) | temp_in | PL | single_source |
| OEM-4-O | Signal ground | sensor_ground | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | BR | single_source |
| OEM-4-P | Coolant temperature (ECT) | temp_in | FT450-A-A24 | White input 5 (water temp) | temp_in | RL | single_source |
| OEM-4-Q | NC | — | — | — | — | unverified | |
| OEM-4-R | VVT oil-control solenoid (low-side control) | low_side_out | — | — | — | VY | corroborated |
| OEM-4-S | Ignition switch (IG1) sense | digital_in | — | — | — | BW | single_source |
| OEM-4-T | Generator output voltage (terminal P) | — | — | — | — | Gy | single_source |
| OEM-4-U | NC | — | — | — | — | unverified | |
| OEM-4-V | Throttle position (TPS) | analog_in | FT450-A-A21 | White input 2 | analog_in | GB | single_source |
| OEM-4-W | Front O2 signal | lambda_nb_in | FT450-A-A25 | White input 6 (fuel pressure) | analog_in | L | single_source |
| OEM-4-X | Mass air flow (MAF) | analog_in | FT450-A-A20 | White input 1 | analog_in | P | single_source |
| OEM-4-Y | NC | — | — | — | — | unverified | |
| OEM-4-Z | TCM (automatic only) | — | — | — | — | PB | single_source |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-2-P | SP-14V-1 | 0.85 | no route | ISC valve +14V feed | — | |
| W2 | OEM-4-AF | SP-14V-1 | 0.85 | no route | ECU power +14V (main relay) | — | |
| W3 | OEM-4-D | SP-14V-1 | 0.85 | no route | VVT oil-control solenoid +12V feed | — | |
| W4 | SP-14V-1 | FT450-A-A13 | 0.85 | no route | +12V switched | — | |
| W5 | OEM-3-A | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W6 | OEM-3-B | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W7 | OEM-4-A | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W8 | SP-GND-1 | FT450-A-A7 | 0.85 | no route | Power ground | — | |
| W9 | OEM-4-O | SP-0V-1 | 0.5 | no route | Signal ground | — | |
| W10 | SP-0V-1 | FT450-A-A12 | 0.5 | no route | Signal ground | — | |
| W11 | OEM-4-L | FT450-A-A14 | 0.5 | no route | +5V sensor supply | — | |
| W12 | OEM-3-Y | FT450-A-A18 | 0.5 | no route | Crank position (CKP) | — | |
| W13 | SP-0V-1 | FT450-A-A18 | 0.5 | no route | RPM reference (crank -) | — | |
| W14 | OEM-3-V | FT450-A-A17 | 0.5 | no route | Cam position (CMP) | — | |
| W15 | OEM-3-F | FT450-A-A8 | 0.5 | no route | Ignition 1 (coils 1+4, wasted spark) | — | |
| W16 | OEM-3-I | FT450-A-A9 | 0.5 | no route | Ignition 2 (coils 2+3, wasted spark) | — | |
| W17 | OEM-2-A | FT450-A-A1 | 0.5 | no route | Injector 1 | — | |
| W18 | OEM-2-D | FT450-A-A2 | 0.5 | no route | Injector 2 | — | |
| W19 | OEM-2-G | FT450-A-A1 | 0.5 | no route | Injector 3 | — | |
| W20 | OEM-2-J | FT450-A-A2 | 0.5 | no route | Injector 4 | — | |
| W21 | OEM-2-B | FT450-A-A6 | 0.5 | no route | Cooling fan relay | — | |
| W22 | OEM-2-C | FT450-A-A3 | 0.5 | no route | Condenser fan relay | — | |
| W23 | OEM-2-K | FT450-A-A4 | 0.5 | no route | A/C clutch relay | — | |
| W24 | OEM-2-M | FT450-A-A5 | 0.5 | no route | Fuel pump relay | — | |
| W25 | OEM-4-X | FT450-A-A20 | 0.5 | no route | Mass air flow (MAF) | — | |
| W26 | OEM-4-AE | FT450-A-A23 | 0.5 | no route | Pressure sensor (Mazda: EGR boost sensor) | — | |
| W27 | OEM-4-V | FT450-A-A21 | 0.5 | no route | Throttle position (TPS) | — | |
| W28 | OEM-4-AA | FT450-A-A22 | 0.5 | no route | Rear O2 signal | — | |
| W29 | OEM-4-W | FT450-A-A25 | 0.5 | no route | Front O2 signal | — | |
| W30 | OEM-4-P | FT450-A-A24 | 0.5 | no route | Coolant temperature (ECT) | — | |
| W31 | OEM-4-N | FT450-A-A26 | 0.5 | no route | Intake air temperature (IAT) | — |
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 (8)
| Severity | Code | Subject | Message |
|---|---|---|---|
| error | NET_MERGED | FT450-A-A1 + OEM-2-A + OEM-2-G | 2 different OEM functions share one net: OEM-2-A Injector 1; OEM-2-G Injector 3 |
| error | NET_MERGED | FT450-A-A2 + OEM-2-D + OEM-2-J | 2 different OEM functions share one net: OEM-2-D Injector 2; OEM-2-J Injector 4 |
| warn | LOAD_UNKNOWN | FT450-A-A3 | FT450-A-A3 "Aux 1" drives OEM-2-C Condenser 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-2-K 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-2-M 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-2-B Cooling fan relay (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| info | NET_FAMILY | FT450-A-A12 ↔ FT450-A-A18 | FT450-A-A12 "Signal ground" [sensor_ground] is wired to FT450-A-A18 "RPM reference (crank -)" [trigger_in]. Trigger return tied to sensor/trigger ground: correct for single-ended trigger inputs. |
| info | UNMAPPED | OEM | 35 optional OEM pins are not mapped: OEM-2-E EGR valve; OEM-2-F EGR valve; OEM-2-H EGR valve; OEM-2-I EGR valve; OEM-2-N VTCS solenoid (intake butterflies); OEM-2-O Fuel pump relay (non-immobiliser); OEM-2-Q ISC valve low side; OEM-2-R Malfunction indicator lamp (MIL); OEM-3-C Purge solenoid valve; OEM-3-D EGR boost solenoid; OEM-3-H Main relay; OEM-3-J Front O2 heater; OEM-3-K EVAP leak detection pump; OEM-3-M Alternator control; OEM-3-O Tachometer output; OEM-3-P Rear O2 heater; OEM-3-Q Data link connector (K-line); OEM-3-S Immobiliser; OEM-3-T Vehicle speed; OEM-3-U Charge lamp; OEM-4-AC TCM (automatic only); OEM-4-AD Fuel level; OEM-4-AH EVAP leak detection pump solenoid valve; OEM-4-B Brake switch; OEM-4-C Power steering pressure switch; OEM-4-E Diagnostic (DLC TEN) (NA); OEM-4-F A/C request; OEM-4-H Neutral switch; OEM-4-I Clutch switch; OEM-4-J VTCS vacuum switch; OEM-4-M Knock sensor; OEM-4-R VVT oil-control solenoid (low-side control); OEM-4-S Ignition switch (IG1) sense; OEM-4-T Generator output voltage (terminal P); OEM-4-Z TCM (automatic only) |
Accepted (1)
| Code | Subject | Reason | By |
|---|---|---|---|
| REQUIRED_UNMAPPED | OEM-4-AG | 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 AG: Constant +12V: FuelTech FT450 has no battery-constant input; not needed - OEM-4 M: Knock sensor: no free knock input on FuelTech FT450 - OEM-4 S: Ignition switch (IG1) sense: key-on 12 V sense — optional in a swap (the main relay is energized from keyed 12 V, not from this pin); FuelTech FT450 has no dedicated key-on input - OEM-3 H: Main relay: no free relay_control/low_side/ls_hs/injector/hbridge rated ≥ 0.2 A on FuelTech FT450 - OEM-2 O: Fuel pump relay (non-immobiliser): no free relay_control/low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-3 J: Front O2 heater: no free heater_low_side/low_side/ls_hs/hbridge on FuelTech FT450 - OEM-3 P: Rear O2 heater: no free heater_low_side/low_side/ls_hs/hbridge on FuelTech FT450 - OEM-2 Q: ISC valve low side: no free low_side/ls_hs/injector/hbridge rated ≥ 1.0 A on FuelTech FT450 - OEM-2 E: EGR valve: no free low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-2 F: EGR valve: no free low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-2 H: EGR valve: no free low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-2 I: EGR valve: no free low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-2 N: VTCS solenoid (intake butterflies): no free low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-2 R: Malfunction indicator lamp (MIL): no free low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-3 C: Purge solenoid valve: no free low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-3 K: EVAP leak detection pump: no free low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-3 M: Alternator control: no free low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-3 U: Charge lamp: no free low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-4 AH: EVAP leak detection pump solenoid valve: no free low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-4 R: VVT oil-control solenoid (low-side control): no free low_side/ls_hs/injector/hbridge on FuelTech FT450 - OEM-3 O: Tachometer output: no free tacho/frequency_out/low_side/ls_hs on FuelTech FT450 - OEM-4 AD: Fuel level: no free analog_0_5 on FuelTech FT450 - OEM-3 T: Vehicle speed: no free frequency_in/switch_in on FuelTech FT450 - OEM-3 S: Immobiliser: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-4 B: Brake switch: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-4 C: Power steering pressure switch: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-4 F: A/C request: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-4 H: Neutral switch: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-4 I: Clutch switch: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-4 J: VTCS vacuum switch: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-3 Q: Data link connector (K-line): no free k_line on FuelTech FT450 - OEM-4 E: Diagnostic (DLC TEN) (NA): no free k_line on FuelTech FT450 - OEM-3 D: EGR boost solenoid: not classified in the library; wire by hand - OEM-4 AC: TCM (automatic only): not classified in the library; wire by hand - OEM-4 T: Generator output voltage (terminal P): not classified in the library; wire by hand - OEM-4 Z: TCM (automatic only): not classified in the library; wire by hand
Sources
| Reliability | Kind | Title | URL | Archive | Captured | SHA-256 |
|---|---|---|---|---|---|---|
| 4 | oem_manual | 2005 Mazda MX-5 Miata Engine Performance Control System (PCM terminal voltage reference, BP and BP WITH TC) | https://trull.org/alex/pubmirror/www.mellens.net/mazda/Mazda-Miata-2005/engine_control_system.pdf | — | — | — |
| 4 | vendor_doc | Adaptronic eSel039 Select Plugin ECU for Mazda MX5 / Miata NB8B/C (OEM ECU pinout) | https://www.miataturbo.net/attachments/ecus-tuning-54/04-msm-ecu-pinout-104032/nb8bc_oem_ecu_pinouts-224948d1602912806 | — | — | — |
| 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 MX5NB2X install manual (NB2 2001-05) | https://linkecu.com/documentation/MX5XNB2.pdf | archive | 2026-10-05 | 741efdd9f2c8 |
| 4 | oem_manual | Mazda MX-5 NB2 (2003) wiring diagram — engine / starting / charging | https://web.archive.org/web/20191104195207/http://mellens.net/mazda/mazda_miata_extra_manual/2003_wiring.pdf | — | 2026-10-05 | 5ee0777f12c1 |
| 2 | expert_report | Justin Barrera — Miata NA/NB wiring corrections | — | — | — | — |