MX-5 Miata NA8 1994-95 (BP-ZE, 1.8, OBD-I) → FuelTech FT450 (auto)
MX-5 Miata NA8 1994-95 (BP-ZE, 1.8, OBD-I) — FuelTech — FT450
⚠ 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 | 30 wires · 6 connectors · 2 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 | SP-14V-1 | FT450-A-A13 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | OEM-2-A | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | OEM-2-B | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | SP-GND-1 | FT450-A-A7 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | OEM-2-C | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | OEM-2-D | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | OEM-2-F | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | SP-0V-1 | FT450-A-A12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | OEM-2-K | FT450-A-A14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | OEM-2-E | FT450-A-A18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | SP-0V-1 | FT450-A-A18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-2-G | FT450-A-A17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-1-G | FT450-A-A8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | OEM-1-H | FT450-A-A9 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | OEM-2-U | FT450-A-A1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-2-V | FT450-A-A2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-2-Y | FT450-A-A1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-2-Z | FT450-A-A2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-2-O | FT450-A-A20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-2-M | FT450-A-A21 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-2-Q | FT450-A-A24 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-1-J | FT450-A-A6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-1-R | FT450-A-A3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-2-S | FT450-A-A4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-2-T | FT450-A-A5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-2-N | FT450-A-A22 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-2-P | FT450-A-A26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-1-C | FT450-A-A23 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-1-O | FT450-A-A25 | 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 | 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) | — | W16 | — | 0.5 | OEM-2-U | — | — | — |
| A1 | Injector 1 (Bank A) | — | W18 | — | 0.5 | OEM-2-Y | — | — | — |
| A10 | Ignition 3 | — | — | — | — | — | — | — | — |
| A11 | Ignition 4 | — | — | — | — | — | — | — | — |
| A12 | Signal ground | — | W9 | — | 0.5 | SP-0V-1 | — | — | — |
| A13 | +12V switched | — | W2 | — | 0.85 | SP-14V-1 | — | — | — |
| A14 | +5V sensor supply | — | W10 | — | 0.5 | OEM-2-K | — | — | — |
| A15 | CAN A LOW | — | — | — | — | — | — | — | — |
| A16 | CAN A HIGH | — | — | — | — | — | — | — | — |
| A17 | Phase input (cam) | — | W13 | — | 0.5 | OEM-2-G | — | — | — |
| A18 | RPM reference (crank -) | — | W11 | — | 0.5 | OEM-2-E | — | — | — |
| A18 | RPM reference (crank -) | — | W12 | — | 0.5 | SP-0V-1 | — | — | — |
| A19 | RPM signal (crank +) | — | — | — | — | — | — | — | — |
| A2 | Injector 2 (Bank A) | — | W17 | — | 0.5 | OEM-2-V | — | — | — |
| A2 | Injector 2 (Bank A) | — | W19 | — | 0.5 | OEM-2-Z | — | — | — |
| A20 | White input 1 | — | W20 | — | 0.5 | OEM-2-O | — | — | — |
| A21 | White input 2 | — | W21 | — | 0.5 | OEM-2-M | — | — | — |
| A22 | White input 3 (TPS) | — | W27 | — | 0.5 | OEM-2-N | — | — | — |
| A23 | White input 4 (oil pressure) | — | W29 | — | 0.5 | OEM-1-C | — | — | — |
| A24 | White input 5 (water temp) | — | W22 | — | 0.5 | OEM-2-Q | — | — | — |
| A25 | White input 6 (fuel pressure) | — | W30 | — | 0.5 | OEM-1-O | — | — | — |
| A26 | White input 7 (air temp) | — | W28 | — | 0.5 | OEM-2-P | — | — | — |
| A3 | Aux 1 | — | W24 | — | 0.5 | OEM-1-R | — | — | — |
| A4 | Aux 2 | — | W25 | — | 0.5 | OEM-2-S | — | — | — |
| A5 | Aux 3 | — | W26 | — | 0.5 | OEM-2-T | — | — | — |
| A6 | Aux 4 (fuel pump / relays) | — | W23 | — | 0.5 | OEM-1-J | — | — | — |
| A7 | Power ground | — | W5 | — | 0.85 | SP-GND-1 | — | — | — |
| A8 | Ignition 1 | — | W14 | — | 0.5 | OEM-1-G | — | — | — |
| A9 | Ignition 2 | — | W15 | — | 0.5 | OEM-1-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 | — | — | — |
| C | Start signal | — | W29 | — | 0.5 | FT450-A-A23 | — | — | — |
| D | Data link connector | — | — | — | — | — | — | — | — |
| E | Malfunction indicator lamp (MIL) | — | — | — | — | — | — | — | — |
| 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 | Powertrain control module (transmission) | — | — | — | — | — | — | — | — |
| J | A/C relay | — | W23 | — | 0.5 | FT450-A-A6 | — | — | — |
| L | Coolant fan relay | — | — | — | — | — | — | — | — |
| M | Vehicle speed | — | — | — | — | — | — | — | — |
| N | Powertrain control module (transmission) | — | — | — | — | — | — | — | — |
| O | Stop light switch | — | W30 | — | 0.5 | FT450-A-A25 | — | — | — |
| P | Power steering pressure switch | — | — | — | — | — | — | — | — |
| Q | A/C request | — | — | — | — | — | — | — | — |
| R | Cooling fan relay | — | W24 | — | 0.5 | FT450-A-A3 | — | — | — |
| S | Heater control unit | — | — | — | — | — | — | — | — |
| T | Unknown | — | — | — | — | — | — | — | — |
| U | Unknown | — | — | — | — | — | — | — | — |
| V | Neutral/clutch switch | — | — | — | — | — | — | — | — |
OEM-2
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Power ground | — | W3 | — | 0.85 | SP-GND-1 | — | — | — |
| B | Power ground | — | W4 | — | 0.85 | SP-GND-1 | — | — | — |
| C | Sensor ground (E2) | — | W6 | — | 0.5 | SP-0V-1 | — | — | — |
| D | Sensor ground (E2) | — | W7 | — | 0.5 | SP-0V-1 | — | — | — |
| E | Crank position (CAS NE) | — | W11 | — | 0.5 | FT450-A-A18 | — | — | — |
| F | MAF ground | — | W8 | — | 0.5 | SP-0V-1 | — | — | — |
| G | Cam position (CAS G) | — | W13 | — | 0.5 | FT450-A-A17 | — | — | — |
| H | Data link connector | — | — | — | — | — | — | — | — |
| I | Tachometer output | — | — | — | — | — | — | — | — |
| J | EGR function sensor | — | — | — | — | — | — | — | — |
| K | +5V sensor supply | — | W10 | — | 0.5 | FT450-A-A14 | — | — | — |
| L | Rear defroster relay | — | — | — | — | — | — | — | — |
| M | Throttle position (TPS) | — | W21 | — | 0.5 | FT450-A-A21 | — | — | — |
| N | O2 sensor | — | W27 | — | 0.5 | FT450-A-A22 | — | — | — |
| O | Mass air flow (MAF) | — | W20 | — | 0.5 | FT450-A-A20 | — | — | — |
| P | Intake air temperature (IAT) | — | W28 | — | 0.5 | FT450-A-A26 | — | — | — |
| Q | Coolant temperature (ECT) | — | W22 | — | 0.5 | FT450-A-A24 | — | — | — |
| R | PRC solenoid (fuel pressure regulator) | — | — | — | — | — | — | — | — |
| S | Condenser fan relay | — | W25 | — | 0.5 | FT450-A-A4 | — | — | — |
| T | Fuel pump relay | — | W26 | — | 0.5 | FT450-A-A5 | — | — | — |
| U | Injector 1 | — | W16 | — | 0.5 | FT450-A-A1 | — | — | — |
| V | Injector 2 | — | W17 | — | 0.5 | FT450-A-A2 | — | — | — |
| W | ISC solenoid | — | — | — | — | — | — | — | — |
| X | Evap purge solenoid | — | — | — | — | — | — | — | — |
| 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 | — | — | W6 | — | 0.5 | OEM-2-C | — | — | — |
| 1 | — | — | W7 | — | 0.5 | OEM-2-D | — | — | — |
| 1 | — | — | W8 | — | 0.5 | OEM-2-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 | FT450-A-A13 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W3 | — | 0.85 | OEM-2-A | — | — | — |
| 1 | — | — | W4 | — | 0.85 | OEM-2-B | — | — | — |
| 1 | — | — | W5 | — | 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 | — | — | — | LR | single_source |
| OEM-1-B | ECU power +14V (main relay) | power_in | FT450-A-A13 | +12V switched | power_in | WR | single_source |
| OEM-1-C | Start signal | digital_in | FT450-A-A23 | White input 4 (oil pressure) | analog_in | V | single_source |
| OEM-1-D | Data link connector | serial | — | — | — | WG | single_source |
| OEM-1-E | Malfunction indicator lamp (MIL) | low_side_out | — | — | — | YB | single_source |
| OEM-1-G | Ignition 1 (coils 1+4, wasted spark) | ignition_out | FT450-A-A8 | Ignition 1 | ignition_out | BrY | single_source |
| OEM-1-H | Ignition 2 (coils 2+3, wasted spark) | ignition_out | FT450-A-A9 | Ignition 2 | ignition_out | Br | single_source |
| OEM-1-I | Powertrain control module (transmission) | — | — | — | — | LW | single_source |
| OEM-1-J | A/C relay | low_side_out | FT450-A-A6 | Aux 4 (fuel pump / relays) | low_side_out | single_source | |
| OEM-1-L | Coolant fan relay | low_side_out | — | — | — | BG | single_source |
| OEM-1-M | Vehicle speed | digital_in | — | — | — | GR | single_source |
| OEM-1-N | Powertrain control module (transmission) | — | — | — | — | R | single_source |
| OEM-1-O | Stop light switch | digital_in | FT450-A-A25 | White input 6 (fuel pressure) | analog_in | GB | single_source |
| OEM-1-P | Power steering pressure switch | digital_in | — | — | — | LY | single_source |
| OEM-1-Q | A/C request | digital_in | — | — | — | LgB | single_source |
| OEM-1-R | Cooling fan relay | low_side_out | FT450-A-A3 | Aux 1 | low_side_out | YB | single_source |
| OEM-1-S | Heater control unit | — | — | — | — | LOr | single_source |
| OEM-1-T | Unknown | — | — | — | — | YR | single_source |
| OEM-1-U | Unknown | — | — | — | — | RB | single_source |
| OEM-1-V | Neutral/clutch switch | digital_in | — | — | — | BrW | single_source |
| OEM-2-A | Power ground | ground | FT450-A-A7 | Power ground | ground | B | single_source |
| OEM-2-B | Power ground | ground | FT450-A-A7 | Power ground | ground | B | single_source |
| OEM-2-C | Sensor ground (E2) | sensor_ground | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | BLg | corroborated |
| OEM-2-D | Sensor ground (E2) | sensor_ground | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | BL | corroborated |
| OEM-2-E | Crank position (CAS NE) | trigger_in | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | W | single_source |
| OEM-2-F | MAF ground | sensor_ground | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | BR | single_source |
| OEM-2-G | Cam position (CAS G) | trigger_in | FT450-A-A17 | Phase input (cam) | trigger_in | YL | single_source |
| OEM-2-H | Data link connector | serial | — | — | — | LgY | single_source |
| OEM-2-I | Tachometer output | tacho_out | — | — | — | BW | single_source |
| OEM-2-J | EGR function sensor | — | — | — | — | LgR | single_source |
| OEM-2-K | +5V sensor supply | vref | FT450-A-A14 | +5V sensor supply | vref | LgW | single_source |
| OEM-2-L | Rear defroster relay | low_side_out | — | — | — | LR | single_source |
| OEM-2-M | Throttle position (TPS) | analog_in | FT450-A-A21 | White input 2 | analog_in | RB | single_source |
| OEM-2-N | O2 sensor | lambda_nb_in | FT450-A-A22 | White input 3 (TPS) | analog_in | RL | single_source |
| OEM-2-O | Mass air flow (MAF) | analog_in | FT450-A-A20 | White input 1 | analog_in | R | single_source |
| OEM-2-P | Intake air temperature (IAT) | temp_in | FT450-A-A26 | White input 7 (air temp) | temp_in | RB | single_source |
| OEM-2-Q | Coolant temperature (ECT) | temp_in | FT450-A-A24 | White input 5 (water temp) | temp_in | LW | single_source |
| OEM-2-R | PRC solenoid (fuel pressure regulator) | low_side_out | — | — | — | YG | single_source |
| OEM-2-S | Condenser fan relay | low_side_out | FT450-A-A4 | Aux 2 | low_side_out | LW | single_source |
| OEM-2-T | Fuel pump relay | low_side_out | FT450-A-A5 | Aux 3 | low_side_out | Lg | single_source |
| OEM-2-U | Injector 1 | injector_out | FT450-A-A1 | Injector 1 (Bank A) | injector_out | Y | single_source |
| OEM-2-V | Injector 2 | injector_out | FT450-A-A2 | Injector 2 (Bank A) | injector_out | YB | single_source |
| OEM-2-W | ISC solenoid | low_side_out | — | — | — | LOr | single_source |
| OEM-2-X | Evap purge solenoid | low_side_out | — | — | — | YR | single_source |
| OEM-2-Y | Injector 3 | injector_out | FT450-A-A1 | Injector 1 (Bank A) | injector_out | GW | single_source |
| OEM-2-Z | Injector 4 | injector_out | FT450-A-A2 | Injector 2 (Bank A) | injector_out | G | 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 | SP-14V-1 | FT450-A-A13 | 0.85 | no route | +12V switched | — | |
| W3 | OEM-2-A | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W4 | OEM-2-B | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W5 | SP-GND-1 | FT450-A-A7 | 0.85 | no route | Power ground | — | |
| W6 | OEM-2-C | SP-0V-1 | 0.5 | no route | Sensor ground (E2) | — | |
| W7 | OEM-2-D | SP-0V-1 | 0.5 | no route | Sensor ground (E2) | — | |
| W8 | OEM-2-F | SP-0V-1 | 0.5 | no route | MAF ground | — | |
| W9 | SP-0V-1 | FT450-A-A12 | 0.5 | no route | Signal ground | — | |
| W10 | OEM-2-K | FT450-A-A14 | 0.5 | no route | +5V sensor supply | — | |
| W11 | OEM-2-E | FT450-A-A18 | 0.5 | no route | Crank position (CAS NE) | — | |
| W12 | SP-0V-1 | FT450-A-A18 | 0.5 | no route | RPM reference (crank -) | — | |
| W13 | OEM-2-G | FT450-A-A17 | 0.5 | no route | Cam position (CAS G) | — | |
| W14 | OEM-1-G | FT450-A-A8 | 0.5 | no route | Ignition 1 (coils 1+4, wasted spark) | — | |
| W15 | OEM-1-H | FT450-A-A9 | 0.5 | no route | Ignition 2 (coils 2+3, wasted spark) | — | |
| W16 | OEM-2-U | FT450-A-A1 | 0.5 | no route | Injector 1 | — | |
| W17 | OEM-2-V | FT450-A-A2 | 0.5 | no route | Injector 2 | — | |
| W18 | OEM-2-Y | FT450-A-A1 | 0.5 | no route | Injector 3 | — | |
| W19 | OEM-2-Z | FT450-A-A2 | 0.5 | no route | Injector 4 | — | |
| W20 | OEM-2-O | FT450-A-A20 | 0.5 | no route | Mass air flow (MAF) | — | |
| W21 | OEM-2-M | FT450-A-A21 | 0.5 | no route | Throttle position (TPS) | — | |
| W22 | OEM-2-Q | FT450-A-A24 | 0.5 | no route | Coolant temperature (ECT) | — | |
| W23 | OEM-1-J | FT450-A-A6 | 0.5 | no route | A/C relay | — | |
| W24 | OEM-1-R | FT450-A-A3 | 0.5 | no route | Cooling fan relay | — | |
| W25 | OEM-2-S | FT450-A-A4 | 0.5 | no route | Condenser fan relay | — | |
| W26 | OEM-2-T | FT450-A-A5 | 0.5 | no route | Fuel pump relay | — | |
| W27 | OEM-2-N | FT450-A-A22 | 0.5 | no route | O2 sensor | — | |
| W28 | OEM-2-P | FT450-A-A26 | 0.5 | no route | Intake air temperature (IAT) | — | |
| W29 | OEM-1-C | FT450-A-A23 | 0.5 | no route | Start signal | — | |
| W30 | OEM-1-O | FT450-A-A25 | 0.5 | no route | Stop light switch | — |
Bill of materials
| Category | Part number | Manufacturer | Description | Qty | Unit |
|---|---|---|---|---|---|
| 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 (10)
| Severity | Code | Subject | Message |
|---|---|---|---|
| error | NET_MERGED | FT450-A-A1 + OEM-2-U + OEM-2-Y | 2 different OEM functions share one net: OEM-2-U Injector 1; OEM-2-Y Injector 3 |
| error | NET_MERGED | FT450-A-A2 + OEM-2-V + OEM-2-Z | 2 different OEM functions share one net: OEM-2-V Injector 2; OEM-2-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-2-S Condenser fan 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-T 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-J A/C relay (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | NET_FAMILY | OEM-1-C ↔ FT450-A-A23 | OEM-1-C "Start signal" [digital_in] is wired to FT450-A-A23 "White input 4 (oil pressure)" [analog_in]. Analog and digital on one net. A switch on an analog input works with a pull-up and a threshold; an analog sensor on a digital input loses its value. |
| warn | NET_FAMILY | OEM-1-O ↔ FT450-A-A25 | OEM-1-O "Stop light switch" [digital_in] is wired to FT450-A-A25 "White input 6 (fuel pressure)" [analog_in]. Analog and digital on one net. A switch on an analog input works with a pull-up and a threshold; an analog sensor on a digital input loses its value. |
| 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 | 19 optional OEM pins are not mapped: OEM-1-D Data link connector; OEM-1-E Malfunction indicator lamp (MIL); OEM-1-I Powertrain control module (transmission); OEM-1-L Coolant fan relay; OEM-1-M Vehicle speed; OEM-1-N Powertrain control module (transmission); OEM-1-P Power steering pressure switch; OEM-1-Q A/C request; OEM-1-S Heater control unit; OEM-1-T Unknown; OEM-1-U Unknown; OEM-1-V Neutral/clutch switch; OEM-2-H Data link connector; OEM-2-I Tachometer output; OEM-2-J EGR function sensor; OEM-2-L Rear defroster relay; OEM-2-R PRC solenoid (fuel pressure regulator); OEM-2-W ISC solenoid; OEM-2-X Evap purge solenoid |
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-1 L: Coolant fan relay: no free relay_control/low_side/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-2 L: Rear defroster relay: no free relay_control/low_side/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-2 W: ISC solenoid: 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-2 R: PRC solenoid (fuel pressure regulator): no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-2 X: Evap purge solenoid: no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-2 I: Tachometer output: no free tacho/frequency_out/low_side/ls_hs on FuelTech FT450 - OEM-1 M: Vehicle speed: no free frequency_in/switch_in on FuelTech FT450 - OEM-1 P: Power steering pressure switch: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-1 Q: A/C request: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-1 V: Neutral/clutch switch: no free switch_in/frequency_in/analog_0_5 on FuelTech FT450 - OEM-1 D: Data link connector: no free k_line on FuelTech FT450 - OEM-2 H: Data link connector: no free k_line on FuelTech FT450 - OEM-1 I: Powertrain control module (transmission): not classified in the library; wire by hand - OEM-1 N: Powertrain control module (transmission): not classified in the library; wire by hand - OEM-1 S: Heater control unit: not classified in the library; wire by hand - OEM-1 T: Unknown: not classified in the library; wire by hand - OEM-1 U: Unknown: not classified in the library; wire by hand - OEM-2 J: EGR function sensor: 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 MX5X install manual (NA 1.6/1.8) | https://linkecu.com/documentation/MX5X.pdf | archive | 2026-10-05 | b7f730de9f6e |
| 2 | expert_report | Justin Barrera — Miata NA/NB wiring corrections | — | — | — | — |
| 2 | community_copy | rusefi wiki: 1994 Mazda Miata 1.8 (NA8) ECU pinout | https://github.com/rusefi/rusefi/wiki/Mazda-Miata-1994 | — | 2026-10-08 | 075801b907f4 |