MX-5 Miata Mazdaspeed 2004-05 (BP-ZET turbo, no VVT) → Emtron KV12 (auto)
MX-5 Miata Mazdaspeed 2004-05 (BP-ZET turbo, no VVT) — Emtron — KV12
⚠ NOT CHECKED. Don't build from this.
Drawn by Michael Gnankou · Rev 0 · draft · 2026-10-11
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 | 6: read the Findings page before cutting any wire |
| Size of the job | 4 wires · 5 connectors · 5 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-4-D | KV12-B-18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | OEM-4-E | KV12-B-19 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | OEM-4-AE | KV12-C-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | OEM-4-R | KV12-C-3 | 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 |
|---|---|---|---|---|---|
| No supply/ground nets found to cross-check. | |||||
If any reading doesn't match, stop and get help before powering up.
Revisions
| Rev | Label | By | Date |
|---|---|---|---|
| No revisions yet. | |||
Schematic
Connectors
KV12-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 | — | — | — | — | — | — | — | — | — |
| 6 | — | — | — | — | — | — | — | — | — |
| 7 | — | — | — | — | — | — | — | — | — |
| 8 | Ignition Channel 9 | — | — | — | — | — | — | — | — |
| 9 | Ignition Channel 10 | — | — | — | — | — | — | — | — |
| 10 | Lambda 1 Heater - | — | — | — | — | — | — | — | — |
| 11 | Lambda 2 Heater - | — | — | — | — | — | — | — | — |
| 12 | — | — | — | — | — | — | — | — | — |
| 13 | — | — | — | — | — | — | — | — | — |
| 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 | — | — | — | — | — | — | — | — |
| 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) | — | — | — | — | — | — | — | — |
KV12-B
Mating face
Wire side
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Injection Channel 1 | — | — | — | — | — | — | — | — |
| 2 | Injection Channel 2 | — | — | — | — | — | — | — | — |
| 3 | Injection Channel 3 | — | — | — | — | — | — | — | — |
| 4 | Injection Channel 4 | — | — | — | — | — | — | — | — |
| 5 | Injection Channel 5 | — | — | — | — | — | — | — | — |
| 6 | Injection Channel 6 | — | — | — | — | — | — | — | — |
| 7 | Injection Channel 7 | — | — | — | — | — | — | — | — |
| 8 | Injection Channel 8 | — | — | — | — | — | — | — | — |
| 9 | ECU Ground | — | — | — | — | — | — | — | — |
| 10 | Auxiliary Output 1 | — | — | — | — | — | — | — | — |
| 11 | Auxiliary Output 2 | — | — | — | — | — | — | — | — |
| 12 | Auxiliary Output 3 | — | — | — | — | — | — | — | — |
| 13 | Auxiliary Output 4 | — | — | — | — | — | — | — | — |
| 14 | Auxiliary Output 5 | — | — | — | — | — | — | — | — |
| 15 | Auxiliary Output 6 | — | — | — | — | — | — | — | — |
| 16 | Auxiliary Output 7 | — | — | — | — | — | — | — | — |
| 17 | Auxiliary Output 8 | — | — | — | — | — | — | — | — |
| 18 | Auxiliary Output 9 | — | W1 | — | 0.5 | OEM-4-D | — | — | — |
| 19 | Auxiliary Output 10 | — | W2 | — | 0.5 | OEM-4-E | — | — | — |
| 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 | — | — | — | — | — | — | — | — |
| 27 | Ignition Channel 2 | — | — | — | — | — | — | — | — |
| 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 | — | — | — | — | — | — | — | — |
KV12-C
Mating face
Wire side
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | ECU Ground | — | — | — | — | — | — | — | — |
| 2 | Analog Input Channel 1 | — | W3 | — | 0.5 | OEM-4-AE | — | — | — |
| 3 | Analog Input Channel 2 | — | W4 | — | 0.5 | OEM-4-R | — | — | — |
| 4 | Analog Input Channel 3 | — | — | — | — | — | — | — | — |
| 5 | Analog Input Channel 4 | — | — | — | — | — | — | — | — |
| 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 | — | — | — | — | — | — | — | — |
| 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 | — | — | — | — | — | — | — | — |
| 26 | ECU Ground | — | — | — | — | — | — | — | — |
| 27 | Digital Input 1 | — | — | — | — | — | — | — | — |
| 28 | Digital Input 2 | — | — | — | — | — | — | — | — |
| 29 | Digital Input 3 | — | — | — | — | — | — | — | — |
| 30 | Digital Input 4 | — | — | — | — | — | — | — | — |
| 31 | Digital Input 5 | — | — | — | — | — | — | — | — |
| 32 | Digital Input 6 | — | — | — | — | — | — | — | — |
| 33 | Digital Input 7 | — | — | — | — | — | — | — | — |
| 34 | Digital Input 8 | — | — | — | — | — | — | — | — |
KV12-D
Mating face
Wire side
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | ECU 14V Supply | — | — | — | — | — | — | — | — |
| 2 | Auxiliary Output 13-16 14V Supply | — | — | — | — | — | — | — | — |
| 3 | Sensor Supply 8V | — | — | — | — | — | — | — | — |
| 4 | Crank Index Sensor + | — | — | — | — | — | — | — | — |
| 5 | Crank Index Sensor - | — | — | — | — | — | — | — | — |
| 6 | Sync Sensor + | — | — | — | — | — | — | — | — |
| 7 | Sync Sensor - | — | — | — | — | — | — | — | — |
| 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 | — | — | — | — | — | — | — | — |
| 21 | Sensor Supply Vref1: 5.0V | — | — | — | — | — | — | — | — |
| 22 | Sensor Supply Vref2: 5.0V | — | — | — | — | — | — | — | — |
| 23 | Ethernet Tx + | — | — | — | — | — | — | — | — |
| 24 | Ethernet Tx - | — | — | — | — | — | — | — | — |
| 25 | Ethernet Rx + | — | — | — | — | — | — | — | — |
| 26 | Ethernet Rx - | — | — | — | — | — | — | — | — |
OEM-4
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| AC | Data link connector (DLC TEN, turbo) | — | — | — | — | — | — | — | — |
| AE | BARO/MAP sensor (turbo boost pressure) | — | W3 | — | 0.5 | KV12-C-2 | — | — | — |
| D | Boost control solenoid (turbo) | — | W1 | — | 0.5 | KV12-B-18 | — | — | — |
| E | Boost control solenoid (turbo) | — | W2 | — | 0.5 | KV12-B-19 | — | — | — |
| R | Intake air temperature 2 (IAT2, turbo) | — | W4 | — | 0.5 | KV12-C-3 | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| OEM-4-AC | Data link connector (DLC TEN, turbo) | serial | — | — | — | BrY | single_source |
| OEM-4-AE | BARO/MAP sensor (turbo boost pressure) | analog_in | KV12-C-2 | Analog Input Channel 1 | analog_in | LY | single_source |
| OEM-4-D | Boost control solenoid (turbo) | high_side_out | KV12-B-18 | Auxiliary Output 9 | hbridge_out | Y | single_source |
| OEM-4-E | Boost control solenoid (turbo) | high_side_out | KV12-B-19 | Auxiliary Output 10 | hbridge_out | Y | single_source |
| OEM-4-R | Intake air temperature 2 (IAT2, turbo) | temp_in | KV12-C-3 | Analog Input Channel 2 | analog_in | VY | single_source |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-4-D | KV12-B-18 | 0.5 | no route | Boost control solenoid (turbo) | — | |
| W2 | OEM-4-E | KV12-B-19 | 0.5 | no route | Boost control solenoid (turbo) | — | |
| W3 | OEM-4-AE | KV12-C-2 | 0.5 | no route | BARO/MAP sensor (turbo boost pressure) | — | |
| W4 | OEM-4-R | KV12-C-3 | 0.5 | no route | Intake air temperature 2 (IAT2, turbo) | — |
Bill of materials
| Category | Part number | Manufacturer | Description | Qty | Unit |
|---|---|---|---|---|---|
| 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) | 4.000 | ea |
ECU setup sheet
| Role | Engine ref | Engine signal | Sensor | ECU point | ECU function | ECU class | Setup flag |
|---|---|---|---|---|---|---|---|
| No configured channels. | |||||||
Findings
Open (11)
| Severity | Code | Subject | Message |
|---|---|---|---|
| error | PHYS_REQUIRED_OPEN | KV12-A-19 | KV12-A-19 "ECU Ground" is required but not wired. |
| error | PHYS_REQUIRED_OPEN | KV12-B-34 | KV12-B-34 "ECU Ground" is required but not wired. |
| error | PHYS_REQUIRED_OPEN | KV12-B-9 | KV12-B-9 "ECU Ground" is required but not wired. |
| error | PHYS_REQUIRED_OPEN | KV12-C-1 | KV12-C-1 "ECU Ground" is required but not wired. |
| error | PHYS_REQUIRED_OPEN | KV12-C-26 | KV12-C-26 "ECU Ground" is required but not wired. |
| error | PHYS_REQUIRED_OPEN | KV12-D-1 | KV12-D-1 "ECU 14V Supply" is required but not wired. |
| warn | DATASET_GAP | KV12 A | 5 of 26 cavities on KV12 A have no pin data (5,6,7,12,13). Anything there is invisible to these checks. |
| warn | NET_FAMILY | OEM-4-D ↔ KV12-B-18 | OEM-4-D "Boost control solenoid (turbo)" [high_side_out] is wired to KV12-B-18 "Auxiliary Output 9" [hbridge_out]. A half-bridge can act as a high-side switch only if configured that way. |
| warn | NET_FAMILY | OEM-4-E ↔ KV12-B-19 | OEM-4-E "Boost control solenoid (turbo)" [high_side_out] is wired to KV12-B-19 "Auxiliary Output 10" [hbridge_out]. A half-bridge can act as a high-side switch only if configured that way. |
| info | NET_FAMILY | OEM-4-R ↔ KV12-C-3 | OEM-4-R "Intake air temperature 2 (IAT2, turbo)" [temp_in] is wired to KV12-C-3 "Analog Input Channel 2" [analog_in]. Thermistor on a plain analog input needs a pull-up; check the channel can enable one. |
| info | UNMAPPED | OEM | 1 optional OEM pins are not mapped: OEM-4-AC Data link connector (DLC TEN, turbo) |
Accepted (0)
| Code | Subject | Reason | By |
|---|
Notes
Auto-mapped by auto_map() from the library pin data on 2026-10-11. Review every wire against both manuals before building. Open items: - Main-relay feed: no ecu_main_power pin on the stock or the new ECU - KV12-A 19: ECU Ground: required by Emtron KV12 but no stock pin feeds it; wire by hand - KV12-B 34: ECU Ground: required by Emtron KV12 but no stock pin feeds it; wire by hand - KV12-B 9: ECU Ground: required by Emtron KV12 but no stock pin feeds it; wire by hand - KV12-C 1: ECU Ground: required by Emtron KV12 but no stock pin feeds it; wire by hand - KV12-C 26: ECU Ground: required by Emtron KV12 but no stock pin feeds it; wire by hand - KV12-D 1: ECU 14V Supply: required by Emtron KV12 but no stock pin feeds it; wire by hand Not wired: - OEM-4 AC: Data link connector (DLC TEN, turbo): no free k_line on Emtron KV12 - KV12-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 | 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 | Emtron KV12/KV16 Pinout Rev2 | https://github.com/emtron-australia/help | — | 2026-10-05 | 2f3a1b2d2ed4 |