MX-5 Miata NA6 1990-93 (B6-ZE, 1.6) → Emtron KV16 (auto)
MX-5 Miata NA6 1990-93 (B6-ZE, 1.6) — Emtron — KV16
⚠ NOT CHECKED. Don't build from this.
Drawn by Michael Gnankou · Rev 0 · draft · 2026-10-09
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.
- Cut the sensor-ground-to-chassis wirerequired
Cut the wire in the engine bay that ties the ECU sensor/signal ground (2C/2D, BLK/LT GRN) to chassis ground, so the standalone gets a clean sensor-ground reference. After cutting, verify with a meter: sensor ground ↔ chassis ground reads open (OL) unless the standalone manual says otherwise.
Why: The stock loom bonds sensor ground to chassis ground; a standalone ECU needs its sensor ground isolated from the noisy chassis/power ground, otherwise sensor readings are noisy or wrong.
Where: Engine-bay ground joint near the ECU (1991 EWD Fig.2 shows the sensor-ground run and its joint connector).
Correction reported by Justin Barrera
Unverified — reported by Justin Barrera (Motorsport Wiring Alliance), not yet sourced.
- Bypass the airflow-meter pump switchrecommended
The stock pump is run by the flapper airflow meter's pump-switch contact through the circuit-opening relay, not by the ECU. The standalone harness adds ECU control of the pump relay (ignition-switched, fused); remove/bypass the AFM pump switch so the two do not fight.
Why: There is no stock fuel-pump output at the ECU, so the standalone provides it. Leaving the AFM switch in place leaves a second, unswitched pump path.
Where: Airflow meter connector (pump-switch contact) and circuit-opening relay.
Correction reported by Justin Barrera
Source: 1991 Mazda Miata wiring diagrams (Mitchell reproduction, mellens.net community mirror)
| Status | draft · not yet verified: nobody has reported building and running this harness |
|---|---|
| Open errors | none |
| Size of the job | 39 wires · 9 connectors · 7 part lines |
| Tools | Crimp and extraction tools for each terminal family (see Connectors) · wire strippers · multimeter · heat gun + heat-shrink |
| Terminals | 3-1447221-4 |
| 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 | KV16-D-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | SP-14V-1 | KV16-D-2 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | SP-14V-1 | KV16-D-20 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | OEM-2-A | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | OEM-2-B | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | SP-GND-1 | KV16-A-13 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | SP-GND-1 | KV16-A-19 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | SP-GND-1 | KV16-B-34 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | SP-GND-1 | KV16-B-9 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | SP-GND-1 | KV16-C-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | SP-GND-1 | KV16-C-26 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-2-C | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-2-D | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | SP-0V-1 | KV16-C-17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | SP-0V-1 | KV16-C-25 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-2-K | KV16-D-21 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-2-E | KV16-D-4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | SP-0V-1 | KV16-D-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-2-G | KV16-D-6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | SP-0V-1 | KV16-D-7 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-1-G | KV16-B-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-1-H | KV16-B-27 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-2-U | KV16-B-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-2-V | KV16-B-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-2-Y | KV16-B-3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-2-Z | KV16-B-4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-1-E | KV16-B-14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-2-I | KV16-B-15 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-2-O | KV16-C-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W31 | OEM-2-N | KV16-C-3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W32 | OEM-2-Q | KV16-C-4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W33 | OEM-2-P | KV16-C-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W34 | OEM-1-C | KV16-C-27 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W35 | OEM-1-N | KV16-C-28 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W36 | OEM-1-P | KV16-C-29 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W37 | OEM-1-Q | KV16-C-30 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W38 | OEM-1-V | KV16-C-31 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W39 | OEM-2-L | KV16-C-32 | 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): Cut the sensor-ground-to-chassis wire.
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 | KV16-D-1 | KV16-A-13 | open (OL) | +12 V supply must not touch power ground | |
| 2 | KV16-D-1 | KV16-C-17 | open (OL) | +12 V supply must not touch sensor ground | |
| 3 | KV16-A-13 | KV16-D-21 | open (OL) | power ground must not touch 5 V sensor reference | |
| 4 | KV16-C-17 | KV16-D-21 | open (OL) | sensor ground must not touch 5 V sensor reference | |
| 5 | KV16-D-1 | KV16-D-21 | 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
KV16-A
Mating face
Wire side
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Injection Channel 9 | — | — | — | — | — | — | — | — |
| 2 | Injection Channel 10 | — | — | — | — | — | — | — | — |
| 3 | Injection Channel 11 | — | — | — | — | — | — | — | — |
| 4 | Injection Channel 12 | — | — | — | — | — | — | — | — |
| 5 | Injection Channel 13 | — | — | — | — | — | — | — | — |
| 6 | Injection Channel 14 | — | — | — | — | — | — | — | — |
| 7 | Injection Channel 15 | — | — | — | — | — | — | — | — |
| 8 | Ignition Channel 9 | — | — | — | — | — | — | — | — |
| 9 | Ignition Channel 10 | — | — | — | — | — | — | — | — |
| 10 | Lambda 1 Heater - | — | — | — | — | — | — | — | — |
| 11 | Lambda 2 Heater - | — | — | — | — | — | — | — | — |
| 12 | Injection Channel 16 | — | — | — | — | — | — | — | — |
| 13 | ECU Ground | — | W7 | — | 0.85 | SP-GND-1 | — | — | — |
| 14 | Ignition Channel 11 | — | — | — | — | — | — | — | — |
| 15 | Ignition Channel 12 | — | — | — | — | — | — | — | — |
| 16 | Lambda 1 Heater + | — | — | — | — | — | — | — | — |
| 17 | Lambda 2 Heater + | — | — | — | — | — | — | — | — |
| 18 | Lambda 1 Nernst Cell (Vs) | — | — | — | — | — | — | — | — |
| 19 | ECU Ground | — | W8 | — | 0.85 | SP-GND-1 | — | — | — |
| 20 | Lambda 2 Cal Resistor (CalR) | — | — | — | — | — | — | — | — |
| 21 | Lambda 2 Nernst Cell (Vs) | — | — | — | — | — | — | — | — |
| 22 | Lambda 2 Pump Cell (Ip) | — | — | — | — | — | — | — | — |
| 23 | Lambda 2 Virtual Ground (VGnd) | — | — | — | — | — | — | — | — |
| 24 | Lambda 1 Cal Resistor (CalR) | — | — | — | — | — | — | — | — |
| 25 | Lambda 1 Pump Cell (Ip) | — | — | — | — | — | — | — | — |
| 26 | Lambda 1 Virtual Ground (VGnd) | — | — | — | — | — | — | — | — |
KV16-B
Mating face
Wire side
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Injection Channel 1 | — | W24 | — | 0.5 | OEM-2-U | — | — | — |
| 2 | Injection Channel 2 | — | W25 | — | 0.5 | OEM-2-V | — | — | — |
| 3 | Injection Channel 3 | — | W26 | — | 0.5 | OEM-2-Y | — | — | — |
| 4 | Injection Channel 4 | — | W27 | — | 0.5 | OEM-2-Z | — | — | — |
| 5 | Injection Channel 5 | — | — | — | — | — | — | — | — |
| 6 | Injection Channel 6 | — | — | — | — | — | — | — | — |
| 7 | Injection Channel 7 | — | — | — | — | — | — | — | — |
| 8 | Injection Channel 8 | — | — | — | — | — | — | — | — |
| 9 | ECU Ground | — | W10 | — | 0.85 | SP-GND-1 | — | — | — |
| 10 | Auxiliary Output 1 | — | — | — | — | — | — | — | — |
| 11 | Auxiliary Output 2 | — | — | — | — | — | — | — | — |
| 12 | Auxiliary Output 3 | — | — | — | — | — | — | — | — |
| 13 | Auxiliary Output 4 | — | — | — | — | — | — | — | — |
| 14 | Auxiliary Output 5 | — | W28 | — | 0.5 | OEM-1-E | — | — | — |
| 15 | Auxiliary Output 6 | — | W29 | — | 0.5 | OEM-2-I | — | — | — |
| 16 | Auxiliary Output 7 | — | — | — | — | — | — | — | — |
| 17 | Auxiliary Output 8 | — | — | — | — | — | — | — | — |
| 18 | Auxiliary Output 9 | — | — | — | — | — | — | — | — |
| 19 | Auxiliary Output 10 | — | — | — | — | — | — | — | — |
| 20 | Auxiliary Output 11 | — | — | — | — | — | — | — | — |
| 21 | Auxiliary Output 12 | — | — | — | — | — | — | — | — |
| 22 | Auxiliary Output 13 | — | — | — | — | — | — | — | — |
| 23 | Auxiliary Output 14 | — | — | — | — | — | — | — | — |
| 24 | Auxiliary Output 15 | — | — | — | — | — | — | — | — |
| 25 | Auxiliary Output 16 | — | — | — | — | — | — | — | — |
| 26 | Ignition Channel 1 | — | W22 | — | 0.5 | OEM-1-G | — | — | — |
| 27 | Ignition Channel 2 | — | W23 | — | 0.5 | OEM-1-H | — | — | — |
| 28 | Ignition Channel 3 | — | — | — | — | — | — | — | — |
| 29 | Ignition Channel 4 | — | — | — | — | — | — | — | — |
| 30 | Ignition Channel 5 | — | — | — | — | — | — | — | — |
| 31 | Ignition Channel 6 | — | — | — | — | — | — | — | — |
| 32 | Ignition Channel 7 | — | — | — | — | — | — | — | — |
| 33 | Ignition Channel 8 | — | — | — | — | — | — | — | — |
| 34 | ECU Ground | — | W9 | — | 0.85 | SP-GND-1 | — | — | — |
KV16-C
Mating face
Wire side
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | ECU Ground | — | W11 | — | 0.85 | SP-GND-1 | — | — | — |
| 2 | Analog Input Channel 1 | — | W30 | — | 0.5 | OEM-2-O | — | — | — |
| 3 | Analog Input Channel 2 | — | W31 | — | 0.5 | OEM-2-N | — | — | — |
| 4 | Analog Input Channel 3 | — | W32 | — | 0.5 | OEM-2-Q | — | — | — |
| 5 | Analog Input Channel 4 | — | W33 | — | 0.5 | OEM-2-P | — | — | — |
| 6 | Analog Input Channel 5 | — | — | — | — | — | — | — | — |
| 7 | Analog Input Channel 6 | — | — | — | — | — | — | — | — |
| 8 | Analog Input Channel 7 | — | — | — | — | — | — | — | — |
| 9 | Analog Input Channel 8 | — | — | — | — | — | — | — | — |
| 10 | Analog Input Channel 9 | — | — | — | — | — | — | — | — |
| 11 | Analog Input Channel 10 | — | — | — | — | — | — | — | — |
| 12 | Analog Input Channel 11 | — | — | — | — | — | — | — | — |
| 13 | Analog Input Channel 12 | — | — | — | — | — | — | — | — |
| 14 | Analog Input Channel 13 | — | — | — | — | — | — | — | — |
| 15 | Analog Input Channel 14 | — | — | — | — | — | — | — | — |
| 16 | Analog Input Channel 15 | — | — | — | — | — | — | — | — |
| 17 | Analog Sensor 0V Reference | — | W15 | — | 0.5 | SP-0V-1 | — | — | — |
| 18 | Digital Input 9 | — | — | — | — | — | — | — | — |
| 19 | Digital Input 10 | — | — | — | — | — | — | — | — |
| 20 | Digital Input 11 | — | — | — | — | — | — | — | — |
| 21 | Digital Input 12 | — | — | — | — | — | — | — | — |
| 22 | Digital Input 13 | — | — | — | — | — | — | — | — |
| 23 | Digital Input 14 | — | — | — | — | — | — | — | — |
| 24 | Analog Input Channel 16 | — | — | — | — | — | — | — | — |
| 25 | Analog Sensor 0V Reference | — | W16 | — | 0.5 | SP-0V-1 | — | — | — |
| 26 | ECU Ground | — | W12 | — | 0.85 | SP-GND-1 | — | — | — |
| 27 | Digital Input 1 | — | W34 | — | 0.5 | OEM-1-C | — | — | — |
| 28 | Digital Input 2 | — | W35 | — | 0.5 | OEM-1-N | — | — | — |
| 29 | Digital Input 3 | — | W36 | — | 0.5 | OEM-1-P | — | — | — |
| 30 | Digital Input 4 | — | W37 | — | 0.5 | OEM-1-Q | — | — | — |
| 31 | Digital Input 5 | — | W38 | — | 0.5 | OEM-1-V | — | — | — |
| 32 | Digital Input 6 | — | W39 | — | 0.5 | OEM-2-L | — | — | — |
| 33 | Digital Input 7 | — | — | — | — | — | — | — | — |
| 34 | Digital Input 8 | — | — | — | — | — | — | — | — |
KV16-D
Mating face
Wire side
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | ECU 14V Supply | — | W2 | — | 0.85 | SP-14V-1 | — | — | — |
| 2 | Auxiliary Output 13-16 14V Supply | — | W3 | — | 0.85 | SP-14V-1 | — | — | — |
| 3 | Sensor Supply 8V | — | — | — | — | — | — | — | — |
| 4 | Crank Index Sensor + | — | W18 | — | 0.5 | OEM-2-E | — | — | — |
| 5 | Crank Index Sensor - | — | W19 | — | 0.5 | SP-0V-1 | — | — | — |
| 6 | Sync Sensor + | — | W20 | — | 0.5 | OEM-2-G | — | — | — |
| 7 | Sync Sensor - | — | W21 | — | 0.5 | SP-0V-1 | — | — | — |
| 8 | CAN 1H | — | — | — | — | — | — | — | — |
| 9 | EFI Relay Output (Low Side 200mA) | — | — | — | — | — | — | — | — |
| 10 | CAN 2H | — | — | — | — | — | — | — | — |
| 11 | Knock 1 + | — | — | — | — | — | — | — | — |
| 12 | Knock 1 - | — | — | — | — | — | — | — | — |
| 13 | Shield (Crank/Cam/ Knock) | — | — | — | — | — | — | — | — |
| 14 | CAN 1L | — | — | — | — | — | — | — | — |
| 15 | Ignition Switch Input | — | — | — | — | — | — | — | — |
| 16 | CAN 2L | — | — | — | — | — | — | — | — |
| 17 | Knock 2 + | — | — | — | — | — | — | — | — |
| 18 | Knock 2 - | — | — | — | — | — | — | — | — |
| 19 | Analog Output (0.0 - 5.0V) | — | — | — | — | — | — | — | — |
| 20 | Auxiliary Output 9-12 14V Supply | — | W4 | — | 0.85 | SP-14V-1 | — | — | — |
| 21 | Sensor Supply Vref1: 5.0V | — | W17 | — | 0.5 | OEM-2-K | — | — | — |
| 22 | Sensor Supply Vref2: 5.0V | — | — | — | — | — | — | — | — |
| 23 | Ethernet Tx + | — | — | — | — | — | — | — | — |
| 24 | Ethernet Tx - | — | — | — | — | — | — | — | — |
| 25 | Ethernet Rx + | — | — | — | — | — | — | — | — |
| 26 | Ethernet Rx - | — | — | — | — | — | — | — | — |
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 | — | W34 | — | 0.5 | KV16-C-27 | — | — | — |
| E | Malfunction indicator lamp (MIL) | — | W28 | — | 0.5 | KV16-B-14 | — | — | — |
| G | Ignition 1 (coils 1+4, wasted spark) | — | W22 | — | 0.5 | KV16-B-26 | — | — | — |
| H | Ignition 2 (coils 2+3, wasted spark) | — | W23 | — | 0.5 | KV16-B-27 | — | — | — |
| N | Wide-open throttle switch | — | W35 | — | 0.5 | KV16-C-28 | — | — | — |
| P | Power steering pressure switch | — | W36 | — | 0.5 | KV16-C-29 | — | — | — |
| Q | A/C request | — | W37 | — | 0.5 | KV16-C-30 | — | — | — |
| V | Neutral/clutch switch | — | W38 | — | 0.5 | KV16-C-31 | — | — | — |
OEM-2
| 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 | Sensor ground (E2) | — | W13 | — | 0.5 | SP-0V-1 | — | — | — |
| D | Sensor ground (E2) | — | W14 | — | 0.5 | SP-0V-1 | — | — | — |
| E | Crank position (CAS NE) | — | W18 | — | 0.5 | KV16-D-4 | — | — | — |
| F | NC | — | — | — | — | — | — | — | — |
| G | Cam position (CAS G) | — | W20 | — | 0.5 | KV16-D-6 | — | — | — |
| I | Tachometer output | — | W29 | — | 0.5 | KV16-B-15 | — | — | — |
| K | +5V sensor supply | — | W17 | — | 0.5 | KV16-D-21 | — | — | — |
| L | Idle switch (TPS) | — | W39 | — | 0.5 | KV16-C-32 | — | — | — |
| N | O2 sensor | — | W31 | — | 0.5 | KV16-C-3 | — | — | — |
| O | Air flow meter (AFM) | — | W30 | — | 0.5 | KV16-C-2 | — | — | — |
| P | Intake air temperature (IAT) | — | W33 | — | 0.5 | KV16-C-5 | — | — | — |
| Q | Coolant temperature (ECT) | — | W32 | — | 0.5 | KV16-C-4 | — | — | — |
| U | Injector 1 & 3 (batch) | — | W24 | — | 0.5 | KV16-B-1 | — | — | — |
| V | Injector 2 & 4 (batch) | — | W25 | — | 0.5 | KV16-B-2 | — | — | — |
| Y | Injector 3 (California sequential) | — | W26 | — | 0.5 | KV16-B-3 | — | — | — |
| Z | Injector 4 (California sequential) | — | W27 | — | 0.5 | KV16-B-4 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W13 | — | 0.5 | OEM-2-C | — | — | — |
| 1 | — | — | W14 | — | 0.5 | OEM-2-D | — | — | — |
| 1 | — | — | W15 | — | 0.5 | KV16-C-17 | — | — | — |
| 1 | — | — | W16 | — | 0.5 | KV16-C-25 | — | — | — |
| 1 | — | — | W19 | — | 0.5 | KV16-D-5 | — | — | — |
| 1 | — | — | W21 | — | 0.5 | KV16-D-7 | — | — | — |
SP-14V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W1 | — | 0.85 | OEM-1-B | — | — | — |
| 1 | — | — | W2 | — | 0.85 | KV16-D-1 | — | — | — |
| 1 | — | — | W3 | — | 0.85 | KV16-D-2 | — | — | — |
| 1 | — | — | W4 | — | 0.85 | KV16-D-20 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W5 | — | 0.85 | OEM-2-A | — | — | — |
| 1 | — | — | W6 | — | 0.85 | OEM-2-B | — | — | — |
| 1 | — | — | W7 | — | 0.85 | KV16-A-13 | — | — | — |
| 1 | — | — | W8 | — | 0.85 | KV16-A-19 | — | — | — |
| 1 | — | — | W9 | — | 0.85 | KV16-B-34 | — | — | — |
| 1 | — | — | W10 | — | 0.85 | KV16-B-9 | — | — | — |
| 1 | — | — | W11 | — | 0.85 | KV16-C-1 | — | — | — |
| 1 | — | — | W12 | — | 0.85 | KV16-C-26 | — | — | — |
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 | KV16-D-1 + KV16-D-2 + KV16-D-20 | ECU 14V Supply + Auxiliary Output 13-16 14V Supply + Auxiliary Output 9-12 14V Supply | power_in | single_source | |
| OEM-1-C | Start signal | digital_in | KV16-C-27 | Digital Input 1 | digital_in | single_source | |
| OEM-1-E | Malfunction indicator lamp (MIL) | low_side_out | KV16-B-14 | Auxiliary Output 5 | low_side_out | single_source | |
| OEM-1-G | Ignition 1 (coils 1+4, wasted spark) | ignition_out | KV16-B-26 | Ignition Channel 1 | ignition_out | single_source | |
| OEM-1-H | Ignition 2 (coils 2+3, wasted spark) | ignition_out | KV16-B-27 | Ignition Channel 2 | ignition_out | single_source | |
| OEM-1-N | Wide-open throttle switch | digital_in | KV16-C-28 | Digital Input 2 | digital_in | single_source | |
| OEM-1-P | Power steering pressure switch | digital_in | KV16-C-29 | Digital Input 3 | digital_in | single_source | |
| OEM-1-Q | A/C request | digital_in | KV16-C-30 | Digital Input 4 | digital_in | single_source | |
| OEM-1-V | Neutral/clutch switch | digital_in | KV16-C-31 | Digital Input 5 | digital_in | single_source | |
| OEM-2-A | Power ground | ground | KV16-A-13 + KV16-A-19 + KV16-B-34 + KV16-B-9 + KV16-C-1 + KV16-C-26 | ECU Ground + ECU Ground + ECU Ground + ECU Ground + ECU Ground + ECU Ground | ground | single_source | |
| OEM-2-B | Power ground | ground | KV16-A-13 + KV16-A-19 + KV16-B-34 + KV16-B-9 + KV16-C-1 + KV16-C-26 | ECU Ground + ECU Ground + ECU Ground + ECU Ground + ECU Ground + ECU Ground | ground | single_source | |
| OEM-2-C | Sensor ground (E2) | sensor_ground | KV16-C-17 + KV16-C-25 + KV16-D-5 + KV16-D-7 | Analog Sensor 0V Reference + Analog Sensor 0V Reference + Crank Index Sensor - + Sync Sensor - | sensor_ground + trigger_in | corroborated | |
| OEM-2-D | Sensor ground (E2) | sensor_ground | KV16-C-17 + KV16-C-25 + KV16-D-5 + KV16-D-7 | Analog Sensor 0V Reference + Analog Sensor 0V Reference + Crank Index Sensor - + Sync Sensor - | sensor_ground + trigger_in | corroborated | |
| OEM-2-E | Crank position (CAS NE) | trigger_in | KV16-D-4 | Crank Index Sensor + | trigger_in | single_source | |
| OEM-2-F | NC | — | — | — | — | corroborated | |
| OEM-2-G | Cam position (CAS G) | trigger_in | KV16-D-6 | Sync Sensor + | trigger_in | single_source | |
| OEM-2-I | Tachometer output | tacho_out | KV16-B-15 | Auxiliary Output 6 | low_side_out | single_source | |
| OEM-2-K | +5V sensor supply | vref | KV16-D-21 | Sensor Supply Vref1: 5.0V | vref | single_source | |
| OEM-2-L | Idle switch (TPS) | digital_in | KV16-C-32 | Digital Input 6 | digital_in | single_source | |
| OEM-2-N | O2 sensor | lambda_nb_in | KV16-C-3 | Analog Input Channel 2 | analog_in | single_source | |
| OEM-2-O | Air flow meter (AFM) | analog_in | KV16-C-2 | Analog Input Channel 1 | analog_in | single_source | |
| OEM-2-P | Intake air temperature (IAT) | temp_in | KV16-C-5 | Analog Input Channel 4 | analog_in | single_source | |
| OEM-2-Q | Coolant temperature (ECT) | temp_in | KV16-C-4 | Analog Input Channel 3 | analog_in | single_source | |
| OEM-2-U | Injector 1 & 3 (batch) | injector_out | KV16-B-1 | Injection Channel 1 | injector_out | corroborated | |
| OEM-2-V | Injector 2 & 4 (batch) | injector_out | KV16-B-2 | Injection Channel 2 | injector_out | corroborated | |
| OEM-2-Y | Injector 3 (California sequential) | injector_out | KV16-B-3 | Injection Channel 3 | injector_out | corroborated | |
| OEM-2-Z | Injector 4 (California sequential) | injector_out | KV16-B-4 | Injection Channel 4 | injector_out | corroborated |
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 | KV16-D-1 | 0.85 | no route | ECU 14V Supply | — | |
| W3 | SP-14V-1 | KV16-D-2 | 0.85 | no route | Auxiliary Output 13-16 14V Supply | — | |
| W4 | SP-14V-1 | KV16-D-20 | 0.85 | no route | Auxiliary Output 9-12 14V Supply | — | |
| W5 | OEM-2-A | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W6 | OEM-2-B | SP-GND-1 | 0.85 | no route | Power ground | — | |
| W7 | SP-GND-1 | KV16-A-13 | 0.85 | no route | ECU Ground | — | |
| W8 | SP-GND-1 | KV16-A-19 | 0.85 | no route | ECU Ground | — | |
| W9 | SP-GND-1 | KV16-B-34 | 0.85 | no route | ECU Ground | — | |
| W10 | SP-GND-1 | KV16-B-9 | 0.85 | no route | ECU Ground | — | |
| W11 | SP-GND-1 | KV16-C-1 | 0.85 | no route | ECU Ground | — | |
| W12 | SP-GND-1 | KV16-C-26 | 0.85 | no route | ECU Ground | — | |
| W13 | OEM-2-C | SP-0V-1 | 0.5 | no route | Sensor ground (E2) | — | |
| W14 | OEM-2-D | SP-0V-1 | 0.5 | no route | Sensor ground (E2) | — | |
| W15 | SP-0V-1 | KV16-C-17 | 0.5 | no route | Analog Sensor 0V Reference | — | |
| W16 | SP-0V-1 | KV16-C-25 | 0.5 | no route | Analog Sensor 0V Reference | — | |
| W17 | OEM-2-K | KV16-D-21 | 0.5 | no route | +5V sensor supply | — | |
| W18 | OEM-2-E | KV16-D-4 | 0.5 | no route | Crank position (CAS NE) | — | |
| W19 | SP-0V-1 | KV16-D-5 | 0.5 | no route | Crank Index Sensor - | — | |
| W20 | OEM-2-G | KV16-D-6 | 0.5 | no route | Cam position (CAS G) | — | |
| W21 | SP-0V-1 | KV16-D-7 | 0.5 | no route | Sync Sensor - | — | |
| W22 | OEM-1-G | KV16-B-26 | 0.5 | no route | Ignition 1 (coils 1+4, wasted spark) | — | |
| W23 | OEM-1-H | KV16-B-27 | 0.5 | no route | Ignition 2 (coils 2+3, wasted spark) | — | |
| W24 | OEM-2-U | KV16-B-1 | 0.5 | no route | Injector 1 & 3 (batch) | — | |
| W25 | OEM-2-V | KV16-B-2 | 0.5 | no route | Injector 2 & 4 (batch) | — | |
| W26 | OEM-2-Y | KV16-B-3 | 0.5 | no route | Injector 3 (California sequential) | — | |
| W27 | OEM-2-Z | KV16-B-4 | 0.5 | no route | Injector 4 (California sequential) | — | |
| W28 | OEM-1-E | KV16-B-14 | 0.5 | no route | Malfunction indicator lamp (MIL) | — | |
| W29 | OEM-2-I | KV16-B-15 | 0.5 | no route | Tachometer output | — | |
| W30 | OEM-2-O | KV16-C-2 | 0.5 | no route | Air flow meter (AFM) | — | |
| W31 | OEM-2-N | KV16-C-3 | 0.5 | no route | O2 sensor | — | |
| W32 | OEM-2-Q | KV16-C-4 | 0.5 | no route | Coolant temperature (ECT) | — | |
| W33 | OEM-2-P | KV16-C-5 | 0.5 | no route | Intake air temperature (IAT) | — | |
| W34 | OEM-1-C | KV16-C-27 | 0.5 | no route | Start signal | — | |
| W35 | OEM-1-N | KV16-C-28 | 0.5 | no route | Wide-open throttle switch | — | |
| W36 | OEM-1-P | KV16-C-29 | 0.5 | no route | Power steering pressure switch | — | |
| W37 | OEM-1-Q | KV16-C-30 | 0.5 | no route | A/C request | — | |
| W38 | OEM-1-V | KV16-C-31 | 0.5 | no route | Neutral/clutch switch | — | |
| W39 | OEM-2-L | KV16-C-32 | 0.5 | no route | Idle switch (TPS) | — |
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 |
| connector | 3-1437290-7 | TE | Superseal 1.0 26-way plug | 1.000 | ea |
| connector | 3-1437290-8 | TE | Superseal 1.0 26-way plug, Key 2 | 1.000 | ea |
| connector | 4-1437290-0 | TE | Superseal 1.0 34-way plug, Key 1 | 1.000 | ea |
| connector | 4-1437290-1 | TE | Superseal 1.0 34-way plug, Key 2 | 1.000 | ea |
| terminal | 3-1447221-4 | TE | Superseal 1.0 socket terminal, 20 AWG (0.5 sq mm) | 34.000 | ea |
ECU setup sheet
| Role | Engine ref | Engine signal | Sensor | ECU point | ECU function | ECU class | Setup flag |
|---|---|---|---|---|---|---|---|
| No configured channels. | |||||||
Findings
Open (5)
| Severity | Code | Subject | Message |
|---|---|---|---|
| warn | NO_FUEL_PUMP | fuel pump | This engine harness has no fuel-pump control path: no fuel-pump relay output is wired to the new ECU. If the stock car switches the pump outside the ECU (an airflow-meter contact or a separate module), the standalone must drive the pump relay itself — see the install notes for this car. |
| info | NET_FAMILY | OEM-2-C ↔ KV16-D-5 | OEM-2-C "Sensor ground (E2)" [sensor_ground] is wired to KV16-D-5 "Crank Index Sensor -" [trigger_in]. Trigger return tied to sensor/trigger ground: correct for single-ended trigger inputs. |
| info | NET_FAMILY | OEM-2-I ↔ KV16-B-15 | OEM-2-I "Tachometer output" [tacho_out] is wired to KV16-B-15 "Auxiliary Output 6" [low_side_out]. Tacho as a low-side output: check the tach needs a pull-up. |
| info | NET_FAMILY | OEM-2-P ↔ KV16-C-5 | OEM-2-P "Intake air temperature (IAT)" [temp_in] is wired to KV16-C-5 "Analog Input Channel 4" [analog_in]. Thermistor on a plain analog input needs a pull-up; check the channel can enable one. |
| info | NET_FAMILY | OEM-2-Q ↔ KV16-C-4 | OEM-2-Q "Coolant temperature (ECT)" [temp_in] is wired to KV16-C-4 "Analog Input Channel 3" [analog_in]. Thermistor on a plain analog input needs a pull-up; check the channel can enable one. |
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 2026-10-09. Review every wire against both manuals before building. Open items: - Fuel-pump control: Emtron KV16 needs to drive the fuel pump, but the stock ECU has no fuel-pump output (an airflow-meter contact or a separate module runs it). Add a fuel-pump relay on a spare low-side output — see the install notes for this car. Not wired: - OEM-1 A: Constant +12V: Emtron KV16 has no battery-constant input; not needed - KV16-D 15: Ignition Switch Input: not fed (the stock ECU has no ignition-sense pin); feed it from a switched-ignition source
Sources
| Reliability | Kind | Title | URL | Archive | Captured | SHA-256 |
|---|---|---|---|---|---|---|
| 4 | vendor_doc | Emtron KV12/KV16 Pinout Rev2 | https://github.com/emtron-australia/help | — | 2026-10-05 | 2f3a1b2d2ed4 |
| 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 | community_copy | 1991 Mazda Miata wiring diagrams (Mitchell reproduction, mellens.net community mirror) | https://trull.org/alex/pubmirror/www.mellens.net/mazda/Mazda-Miata-1991-1993/1991_wiring.pdf | — | 2026-10-08 | 6f957a38ed49 |
| 2 | expert_report | Justin Barrera — Miata NA/NB wiring corrections | — | — | — | — |