VW Corrado VR6 12v (AAA) Motronic M2.9 OBD1 → Speeduino Speeduino v0.4 (auto)
VW Corrado VR6 12v (AAA) Motronic M2.9 OBD1 — Speeduino — Speeduino
⚠ NOT CHECKED. Don't build from this.
Drawn by Michael Gnankou · Rev 0 · draft · 2026-10-20
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 | 42 wires · 8 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-A-23 | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | OEM-A-38 | MAIN-R-COIL+ | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | NEW-BATT-1 | MAIN-R-IN | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | MAIN-R-COIL- | SP-GND-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | MAIN-R-OUT | SPEEDUINO-PWR-12V | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | OEM-A-1 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | OEM-A-10 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | OEM-A-55 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | OEM-A-56 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | OEM-A-7 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | SP-GND-1 | SPEEDUINO-A-10 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | SP-GND-1 | SPEEDUINO-A-9 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-A-16 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-A-33 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | OEM-A-67 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | SP-0V-1 | SPEEDUINO-A-12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | SP-0V-1 | SPEEDUINO-A-23 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-A-41 | SPEEDUINO-A-13 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-A-68 | SPEEDUINO-A-25 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-A-44 | SPEEDUINO-A-24 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-A-8 | SPEEDUINO-A-7 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-A-60 | SPEEDUINO-A-34 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-A-52 | SPEEDUINO-A-33 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-A-24 | SPEEDUINO-A-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-A-3 | SPEEDUINO-A-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-A-26 | SPEEDUINO-A-3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-A-4 | SPEEDUINO-A-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-A-25 | SPEEDUINO-A-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-A-2 | SPEEDUINO-A-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-A-40 | SPEEDUINO-A-22 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W31 | OEM-A-14 | SPEEDUINO-A-19 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W32 | OEM-A-49 | SPEEDUINO-A-16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W33 | OEM-A-6 | SPEEDUINO-A-15 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W34 | OEM-A-9 | SPEEDUINO-A-36 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W35 | OEM-A-27 | SPEEDUINO-A-37 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W36 | OEM-A-31 | SPEEDUINO-A-35 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W37 | OEM-A-5 | SPEEDUINO-A-38 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W38 | OEM-A-22 | SPEEDUINO-A-17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W39 | OEM-A-20 | SPEEDUINO-A-21 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W40 | OEM-A-15 | SPEEDUINO-A-20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W41 | OEM-A-65 | SPEEDUINO-A-14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W42 | OEM-A-37 | SPEEDUINO-A-18 | 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 | MAIN-R-COIL+ | SPEEDUINO-A-13 | open (OL) | +12 V supply must not touch 5 V sensor reference | |
| 2 | MAIN-R-COIL- | MAIN-R-COIL+ | open (OL) | power ground must not touch +12 V supply | |
| 3 | MAIN-R-COIL- | MAIN-R-OUT | open (OL) | power ground must not touch +12 V supply | |
| 4 | MAIN-R-COIL- | NEW-BATT-1 | open (OL) | power ground must not touch +12 V supply | |
| 5 | MAIN-R-COIL- | OEM-A-23 | open (OL) | power ground must not touch +12 V supply | |
| 6 | MAIN-R-COIL- | SPEEDUINO-A-13 | open (OL) | power ground must not touch 5 V sensor reference | |
| 7 | OEM-A-23 | SPEEDUINO-A-13 | open (OL) | +12 V supply must not touch 5 V sensor reference | |
| 8 | SPEEDUINO-A-12 | MAIN-R-COIL+ | open (OL) | sensor ground must not touch +12 V supply | |
| 9 | SPEEDUINO-A-12 | MAIN-R-OUT | open (OL) | sensor ground must not touch +12 V supply | |
| 10 | SPEEDUINO-A-12 | NEW-BATT-1 | open (OL) | sensor ground must not touch +12 V supply | |
| 11 | SPEEDUINO-A-12 | OEM-A-23 | open (OL) | sensor ground must not touch +12 V supply | |
| 12 | SPEEDUINO-A-12 | SPEEDUINO-A-13 | open (OL) | sensor ground must not touch 5 V sensor reference | |
| 13 | SPEEDUINO-A-13 | MAIN-R-OUT | open (OL) | 5 V sensor reference must not touch +12 V supply | |
| 14 | SPEEDUINO-A-13 | NEW-BATT-1 | open (OL) | 5 V sensor reference must not touch +12 V supply |
If any reading doesn't match, stop and get help before powering up.
Revisions
| Rev | Label | By | Date |
|---|---|---|---|
| No revisions yet. | |||
Schematic
Connectors
MAIN-R
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| COIL+ | Relay coil positive (ignition-switched +12V) | — | W2 | — | 0.5 | OEM-A-38 | — | — | — |
| COIL- | Relay coil negative (ECU low-side driver) | — | W4 | — | 0.5 | SP-GND-1 | — | — | — |
| IN | Relay contact input (battery + via main fuse) | — | W3 | — | 0.85 | NEW-BATT-1 | — | — | — |
| OUT | Relay contact output (switched +12V bus) | — | W5 | — | 0.85 | SPEEDUINO-PWR-12V | — | — | — |
NEW-BATT
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W3 | — | 0.85 | MAIN-R-IN | — | — | — |
OEM-A
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Ground (E-1) | — | W6 | — | 0.85 | SP-GND-1 | — | — | — |
| 10 | Ground (OBD1 EGR enable) | — | W7 | — | 0.85 | SP-GND-1 | — | — | — |
| 14 | Coolant temperature (CLT) | — | W31 | — | 0.5 | SPEEDUINO-A-19 | — | — | — |
| 15 | EGR temperature sensor | — | W40 | — | 0.5 | SPEEDUINO-A-20 | — | — | — |
| 16 | MAF ground | — | W13 | — | 0.5 | SP-0V-1 | — | — | — |
| 17 | MAF signal | — | — | — | — | — | — | — | — |
| 2 | Injector 6 (cyl 6) | — | W29 | — | 0.5 | SPEEDUINO-A-2 | — | — | — |
| 20 | O2 sensor 1 (primary) | — | W39 | — | 0.5 | SPEEDUINO-A-21 | — | — | — |
| 21 | Diagnostic L-line | — | — | — | — | — | — | — | — |
| 22 | Tachometer output | — | W38 | — | 0.5 | SPEEDUINO-A-17 | — | — | — |
| 23 | ECU main power (from engine-electronics relay) | — | W1 | — | 0.85 | SP-14V-1 | — | — | — |
| 24 | Injector 1 (cyl 1) | — | W24 | — | 0.5 | SPEEDUINO-A-1 | — | — | — |
| 25 | Injector 5 (cyl 5) | — | W28 | — | 0.5 | SPEEDUINO-A-1 | — | — | — |
| 26 | Injector 3 (cyl 3) | — | W26 | — | 0.5 | SPEEDUINO-A-3 | — | — | — |
| 27 | Idle air control valve | — | W35 | — | 0.5 | SPEEDUINO-A-37 | — | — | — |
| 3 | Injector 2 (cyl 2) | — | W25 | — | 0.5 | SPEEDUINO-A-2 | — | — | — |
| 31 | EVAP canister purge valve | — | W36 | — | 0.5 | SPEEDUINO-A-35 | — | — | — |
| 33 | Sensor ground bus | — | W14 | — | 0.5 | SP-0V-1 | — | — | — |
| 34 | Knock sensor 1 | — | — | — | — | — | — | — | — |
| 36 | Intake air temperature (IAT) | — | — | — | — | — | — | — | — |
| 37 | A/C compressor switch | — | W42 | — | 0.5 | SPEEDUINO-A-18 | — | — | — |
| 38 | Ignition switch (run/start) | — | W2 | — | 0.5 | MAIN-R-COIL+ | — | — | — |
| 39 | A/C switch (cabin) | — | — | — | — | — | — | — | — |
| 4 | Injector 4 (cyl 4) | — | W27 | — | 0.5 | SPEEDUINO-A-5 | — | — | — |
| 40 | Throttle position sensor 1 | — | W30 | — | 0.5 | SPEEDUINO-A-22 | — | — | — |
| 41 | TPS power (+5V) | — | W18 | — | 0.5 | SPEEDUINO-A-13 | — | — | — |
| 43 | Diagnostic K-line | — | — | — | — | — | — | — | — |
| 44 | Camshaft position sensor (G40) | — | W20 | — | 0.5 | SPEEDUINO-A-24 | — | — | — |
| 49 | Secondary air injection relay control | — | W32 | — | 0.5 | SPEEDUINO-A-16 | — | — | — |
| 5 | Check engine light (MIL) | — | W37 | — | 0.5 | SPEEDUINO-A-38 | — | — | — |
| 51 | MFA fuel-consumption signal | — | — | — | — | — | — | — | — |
| 52 | Ignition coil 4 (coil pack pin 4) | — | W23 | — | 0.5 | SPEEDUINO-A-33 | — | — | — |
| 53 | Idle air control valve (2nd) | — | — | — | — | — | — | — | — |
| 54 | Battery constant (+12V) | — | — | — | — | — | — | — | — |
| 55 | Ground (E-3) | — | W8 | — | 0.85 | SP-GND-1 | — | — | — |
| 56 | Ground (E-4) | — | W9 | — | 0.85 | SP-GND-1 | — | — | — |
| 59 | Mass airflow sensor (5th terminal) | — | — | — | — | — | — | — | — |
| 6 | Fuel pump relay control | — | W33 | — | 0.5 | SPEEDUINO-A-15 | — | — | — |
| 60 | Ignition coil 3 (coil pack pin 3) | — | W22 | — | 0.5 | SPEEDUINO-A-34 | — | — | — |
| 65 | Vehicle speed sensor (VSS) | — | W41 | — | 0.5 | SPEEDUINO-A-14 | — | — | — |
| 67 | Crank sensor return (VR-) | — | W15 | — | 0.5 | SP-0V-1 | — | — | — |
| 68 | Crank position sensor (G28, VR+) | — | W19 | — | 0.5 | SPEEDUINO-A-25 | — | — | — |
| 7 | Ground (E-2) | — | W10 | — | 0.85 | SP-GND-1 | — | — | — |
| 8 | Ignition coil 2 (coil pack pin 2) | — | W21 | — | 0.5 | SPEEDUINO-A-7 | — | — | — |
| 9 | Engine electronics relay control | — | W34 | — | 0.5 | SPEEDUINO-A-36 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W13 | — | 0.5 | OEM-A-16 | — | — | — |
| 1 | — | — | W14 | — | 0.5 | OEM-A-33 | — | — | — |
| 1 | — | — | W15 | — | 0.5 | OEM-A-67 | — | — | — |
| 1 | — | — | W16 | — | 0.5 | SPEEDUINO-A-12 | — | — | — |
| 1 | — | — | W17 | — | 0.5 | SPEEDUINO-A-23 | — | — | — |
SP-14V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W1 | — | 0.85 | OEM-A-23 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W4 | — | 0.5 | MAIN-R-COIL- | — | — | — |
| 1 | — | — | W6 | — | 0.85 | OEM-A-1 | — | — | — |
| 1 | — | — | W7 | — | 0.85 | OEM-A-10 | — | — | — |
| 1 | — | — | W8 | — | 0.85 | OEM-A-55 | — | — | — |
| 1 | — | — | W9 | — | 0.85 | OEM-A-56 | — | — | — |
| 1 | — | — | W10 | — | 0.85 | OEM-A-7 | — | — | — |
| 1 | — | — | W11 | — | 0.85 | SPEEDUINO-A-10 | — | — | — |
| 1 | — | — | W12 | — | 0.85 | SPEEDUINO-A-9 | — | — | — |
SPEEDUINO-A
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Injector 1 | — | W24 | — | 0.5 | OEM-A-24 | — | — | — |
| 1 | Injector 1 | — | W28 | — | 0.5 | OEM-A-25 | — | — | — |
| 10 | Ground | — | W11 | — | 0.85 | SP-GND-1 | — | — | — |
| 11 | MAP sensor (0-5V) | — | — | — | — | — | — | — | — |
| 12 | Ground | — | W16 | — | 0.5 | SP-0V-1 | — | — | — |
| 13 | 5V | — | W18 | — | 0.5 | OEM-A-41 | — | — | — |
| 14 | Proto area 1 (flex fuel) | — | W41 | — | 0.5 | OEM-A-65 | — | — | — |
| 15 | Proto area 2 (fan) | — | W33 | — | 0.5 | OEM-A-6 | — | — | — |
| 16 | Proto area 3 (fuel pump) | — | W32 | — | 0.5 | OEM-A-49 | — | — | — |
| 17 | Proto area 4 (tachometer) | — | W38 | — | 0.5 | OEM-A-22 | — | — | — |
| 18 | Proto area 5 (clutch) | — | W42 | — | 0.5 | OEM-A-37 | — | — | — |
| 19 | Coolant temp (CLT) | — | W31 | — | 0.5 | OEM-A-14 | — | — | — |
| 2 | Injector 2 | — | W25 | — | 0.5 | OEM-A-3 | — | — | — |
| 2 | Injector 2 | — | W29 | — | 0.5 | OEM-A-2 | — | — | — |
| 20 | Inlet air temp (IAT) | — | W40 | — | 0.5 | OEM-A-15 | — | — | — |
| 21 | O2 sensor | — | W39 | — | 0.5 | OEM-A-20 | — | — | — |
| 22 | TPS input | — | W30 | — | 0.5 | OEM-A-40 | — | — | — |
| 23 | Ground | — | W17 | — | 0.5 | SP-0V-1 | — | — | — |
| 24 | Cam input / VR2+ | — | W20 | — | 0.5 | OEM-A-44 | — | — | — |
| 25 | Crank input / VR1+ | — | W19 | — | 0.5 | OEM-A-68 | — | — | — |
| 26 | VR2- | — | — | — | — | — | — | — | — |
| 27 | VR1- | — | — | — | — | — | — | — | — |
| 28 | 5V | — | — | — | — | — | — | — | — |
| 29 | Idle stepper 2B | — | — | — | — | — | — | — | — |
| 3 | Injector 3 | — | W26 | — | 0.5 | OEM-A-26 | — | — | — |
| 30 | Idle stepper 2A | — | — | — | — | — | — | — | — |
| 31 | Idle stepper 1A | — | — | — | — | — | — | — | — |
| 32 | Idle stepper 1B | — | — | — | — | — | — | — | — |
| 33 | Ignition 3 | — | W23 | — | 0.5 | OEM-A-52 | — | — | — |
| 34 | Ignition 2 | — | W22 | — | 0.5 | OEM-A-60 | — | — | — |
| 35 | Boost | — | W36 | — | 0.5 | OEM-A-31 | — | — | — |
| 36 | Idle 2 (3-wire idle) | — | W34 | — | 0.5 | OEM-A-9 | — | — | — |
| 37 | PWM idle | — | W35 | — | 0.5 | OEM-A-27 | — | — | — |
| 38 | VVT | — | W37 | — | 0.5 | OEM-A-5 | — | — | — |
| 5 | Injector 4 | — | W27 | — | 0.5 | OEM-A-4 | — | — | — |
| 7 | Ignition 1 | — | W21 | — | 0.5 | OEM-A-8 | — | — | — |
| 8 | Ignition 4 | — | — | — | — | — | — | — | — |
| 9 | Ground | — | W12 | — | 0.85 | SP-GND-1 | — | — | — |
SPEEDUINO-PWR
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 12V | Main power (+12 V switched) | — | W5 | — | 0.85 | MAIN-R-OUT | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| OEM-A-1 | Ground (E-1) | ground | MAIN-R-COIL- + SPEEDUINO-A-10 + SPEEDUINO-A-9 | Relay coil negative (ECU low-side driver) + Ground + Ground | ground + load | single_source | |
| OEM-A-10 | Ground (OBD1 EGR enable) | ground | MAIN-R-COIL- + SPEEDUINO-A-10 + SPEEDUINO-A-9 | Relay coil negative (ECU low-side driver) + Ground + Ground | ground + load | single_source | |
| OEM-A-14 | Coolant temperature (CLT) | temp_in | SPEEDUINO-A-19 | Coolant temp (CLT) | temp_in | single_source | |
| OEM-A-15 | EGR temperature sensor | temp_in | SPEEDUINO-A-20 | Inlet air temp (IAT) | temp_in | single_source | |
| OEM-A-16 | MAF ground | sensor_ground | SPEEDUINO-A-12 + SPEEDUINO-A-23 | Ground + Ground | sensor_ground | single_source | |
| OEM-A-17 | MAF signal | analog_in | — | — | — | single_source | |
| OEM-A-2 | Injector 6 (cyl 6) | injector_out | SPEEDUINO-A-2 | Injector 2 | injector_out | single_source | |
| OEM-A-20 | O2 sensor 1 (primary) | lambda_nb_in | SPEEDUINO-A-21 | O2 sensor | lambda_nb_in | single_source | |
| OEM-A-21 | Diagnostic L-line | serial | — | — | — | single_source | |
| OEM-A-22 | Tachometer output | tacho_out | SPEEDUINO-A-17 | Proto area 4 (tachometer) | tacho_out | single_source | |
| OEM-A-23 | ECU main power (from engine-electronics relay) | power_in | — | — | — | single_source | |
| OEM-A-24 | Injector 1 (cyl 1) | injector_out | SPEEDUINO-A-1 | Injector 1 | injector_out | single_source | |
| OEM-A-25 | Injector 5 (cyl 5) | injector_out | SPEEDUINO-A-1 | Injector 1 | injector_out | single_source | |
| OEM-A-26 | Injector 3 (cyl 3) | injector_out | SPEEDUINO-A-3 | Injector 3 | injector_out | single_source | |
| OEM-A-27 | Idle air control valve | low_side_out | SPEEDUINO-A-37 | PWM idle | low_side_out | single_source | |
| OEM-A-3 | Injector 2 (cyl 2) | injector_out | SPEEDUINO-A-2 | Injector 2 | injector_out | single_source | |
| OEM-A-31 | EVAP canister purge valve | low_side_out | SPEEDUINO-A-35 | Boost | low_side_out | single_source | |
| OEM-A-33 | Sensor ground bus | sensor_ground | SPEEDUINO-A-12 + SPEEDUINO-A-23 | Ground + Ground | sensor_ground | single_source | |
| OEM-A-34 | Knock sensor 1 | knock_in | — | — | — | single_source | |
| OEM-A-36 | Intake air temperature (IAT) | temp_in | — | — | — | single_source | |
| OEM-A-37 | A/C compressor switch | digital_in | SPEEDUINO-A-18 | Proto area 5 (clutch) | digital_in | single_source | |
| OEM-A-38 | Ignition switch (run/start) | digital_in | MAIN-R-COIL+ | Relay coil positive (ignition-switched +12V) | power_in | single_source | |
| OEM-A-39 | A/C switch (cabin) | digital_in | — | — | — | single_source | |
| OEM-A-4 | Injector 4 (cyl 4) | injector_out | SPEEDUINO-A-5 | Injector 4 | injector_out | single_source | |
| OEM-A-40 | Throttle position sensor 1 | analog_in | SPEEDUINO-A-22 | TPS input | analog_in | single_source | |
| OEM-A-41 | TPS power (+5V) | vref | SPEEDUINO-A-13 | 5V | vref | single_source | |
| OEM-A-43 | Diagnostic K-line | serial | — | — | — | single_source | |
| OEM-A-44 | Camshaft position sensor (G40) | trigger_in | SPEEDUINO-A-24 | Cam input / VR2+ | trigger_in | single_source | |
| OEM-A-49 | Secondary air injection relay control | low_side_out | SPEEDUINO-A-16 | Proto area 3 (fuel pump) | low_side_out | single_source | |
| OEM-A-5 | Check engine light (MIL) | low_side_out | SPEEDUINO-A-38 | VVT | low_side_out | single_source | |
| OEM-A-51 | MFA fuel-consumption signal | tacho_out | — | — | — | single_source | |
| OEM-A-52 | Ignition coil 4 (coil pack pin 4) | ignition_out | SPEEDUINO-A-33 | Ignition 3 | ignition_out | single_source | |
| OEM-A-53 | Idle air control valve (2nd) | low_side_out | — | — | — | single_source | |
| OEM-A-54 | Battery constant (+12V) | power_in | — | — | — | single_source | |
| OEM-A-55 | Ground (E-3) | ground | MAIN-R-COIL- + SPEEDUINO-A-10 + SPEEDUINO-A-9 | Relay coil negative (ECU low-side driver) + Ground + Ground | ground + load | single_source | |
| OEM-A-56 | Ground (E-4) | ground | MAIN-R-COIL- + SPEEDUINO-A-10 + SPEEDUINO-A-9 | Relay coil negative (ECU low-side driver) + Ground + Ground | ground + load | single_source | |
| OEM-A-59 | Mass airflow sensor (5th terminal) | sensor_out | — | — | — | single_source | |
| OEM-A-6 | Fuel pump relay control | low_side_out | SPEEDUINO-A-15 | Proto area 2 (fan) | low_side_out | single_source | |
| OEM-A-60 | Ignition coil 3 (coil pack pin 3) | ignition_out | SPEEDUINO-A-34 | Ignition 2 | ignition_out | single_source | |
| OEM-A-65 | Vehicle speed sensor (VSS) | digital_in | SPEEDUINO-A-14 | Proto area 1 (flex fuel) | digital_in | single_source | |
| OEM-A-67 | Crank sensor return (VR-) | sensor_ground | SPEEDUINO-A-12 + SPEEDUINO-A-23 | Ground + Ground | sensor_ground | single_source | |
| OEM-A-68 | Crank position sensor (G28, VR+) | trigger_in | SPEEDUINO-A-25 | Crank input / VR1+ | trigger_in | single_source | |
| OEM-A-7 | Ground (E-2) | ground | MAIN-R-COIL- + SPEEDUINO-A-10 + SPEEDUINO-A-9 | Relay coil negative (ECU low-side driver) + Ground + Ground | ground + load | single_source | |
| OEM-A-8 | Ignition coil 2 (coil pack pin 2) | ignition_out | SPEEDUINO-A-7 | Ignition 1 | ignition_out | single_source | |
| OEM-A-9 | Engine electronics relay control | low_side_out | SPEEDUINO-A-36 | Idle 2 (3-wire idle) | low_side_out | single_source |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-A-23 | SP-14V-1 | 0.85 | no route | ECU main power (from engine-electronics relay) | — | |
| W2 | OEM-A-38 | MAIN-R-COIL+ | 0.5 | no route | Ignition switch (run/start) | — | |
| W3 | NEW-BATT-1 | MAIN-R-IN | 0.85 | no route | Relay contact input (battery + via main fuse) | — | |
| W4 | MAIN-R-COIL- | SP-GND-1 | 0.5 | no route | Relay coil negative (ECU low-side driver) | — | |
| W5 | MAIN-R-OUT | SPEEDUINO-PWR-12V | 0.85 | no route | Relay contact output (switched +12V bus) | — | |
| W6 | OEM-A-1 | SP-GND-1 | 0.85 | no route | Ground (E-1) | — | |
| W7 | OEM-A-10 | SP-GND-1 | 0.85 | no route | Ground (OBD1 EGR enable) | — | |
| W8 | OEM-A-55 | SP-GND-1 | 0.85 | no route | Ground (E-3) | — | |
| W9 | OEM-A-56 | SP-GND-1 | 0.85 | no route | Ground (E-4) | — | |
| W10 | OEM-A-7 | SP-GND-1 | 0.85 | no route | Ground (E-2) | — | |
| W11 | SP-GND-1 | SPEEDUINO-A-10 | 0.85 | no route | Ground | — | |
| W12 | SP-GND-1 | SPEEDUINO-A-9 | 0.85 | no route | Ground | — | |
| W13 | OEM-A-16 | SP-0V-1 | 0.5 | no route | MAF ground | — | |
| W14 | OEM-A-33 | SP-0V-1 | 0.5 | no route | Sensor ground bus | — | |
| W15 | OEM-A-67 | SP-0V-1 | 0.5 | no route | Crank sensor return (VR-) | — | |
| W16 | SP-0V-1 | SPEEDUINO-A-12 | 0.5 | no route | Ground | — | |
| W17 | SP-0V-1 | SPEEDUINO-A-23 | 0.5 | no route | Ground | — | |
| W18 | OEM-A-41 | SPEEDUINO-A-13 | 0.5 | no route | TPS power (+5V) | — | |
| W19 | OEM-A-68 | SPEEDUINO-A-25 | 0.5 | no route | Crank position sensor (G28, VR+) | — | |
| W20 | OEM-A-44 | SPEEDUINO-A-24 | 0.5 | no route | Camshaft position sensor (G40) | — | |
| W21 | OEM-A-8 | SPEEDUINO-A-7 | 0.5 | no route | Ignition coil 2 (coil pack pin 2) | — | |
| W22 | OEM-A-60 | SPEEDUINO-A-34 | 0.5 | no route | Ignition coil 3 (coil pack pin 3) | — | |
| W23 | OEM-A-52 | SPEEDUINO-A-33 | 0.5 | no route | Ignition coil 4 (coil pack pin 4) | — | |
| W24 | OEM-A-24 | SPEEDUINO-A-1 | 0.5 | no route | Injector 1 (cyl 1) | — | |
| W25 | OEM-A-3 | SPEEDUINO-A-2 | 0.5 | no route | Injector 2 (cyl 2) | — | |
| W26 | OEM-A-26 | SPEEDUINO-A-3 | 0.5 | no route | Injector 3 (cyl 3) | — | |
| W27 | OEM-A-4 | SPEEDUINO-A-5 | 0.5 | no route | Injector 4 (cyl 4) | — | |
| W28 | OEM-A-25 | SPEEDUINO-A-1 | 0.5 | no route | Injector 5 (cyl 5) | — | |
| W29 | OEM-A-2 | SPEEDUINO-A-2 | 0.5 | no route | Injector 6 (cyl 6) | — | |
| W30 | OEM-A-40 | SPEEDUINO-A-22 | 0.5 | no route | Throttle position sensor 1 | — | |
| W31 | OEM-A-14 | SPEEDUINO-A-19 | 0.5 | no route | Coolant temperature (CLT) | — | |
| W32 | OEM-A-49 | SPEEDUINO-A-16 | 0.5 | no route | Secondary air injection relay control | — | |
| W33 | OEM-A-6 | SPEEDUINO-A-15 | 0.5 | no route | Fuel pump relay control | — | |
| W34 | OEM-A-9 | SPEEDUINO-A-36 | 0.5 | no route | Engine electronics relay control | — | |
| W35 | OEM-A-27 | SPEEDUINO-A-37 | 0.5 | no route | Idle air control valve | — | |
| W36 | OEM-A-31 | SPEEDUINO-A-35 | 0.5 | no route | EVAP canister purge valve | — | |
| W37 | OEM-A-5 | SPEEDUINO-A-38 | 0.5 | no route | Check engine light (MIL) | — | |
| W38 | OEM-A-22 | SPEEDUINO-A-17 | 0.5 | no route | Tachometer output | — | |
| W39 | OEM-A-20 | SPEEDUINO-A-21 | 0.5 | no route | O2 sensor 1 (primary) | — | |
| W40 | OEM-A-15 | SPEEDUINO-A-20 | 0.5 | no route | EGR temperature sensor | — | |
| W41 | OEM-A-65 | SPEEDUINO-A-14 | 0.5 | no route | Vehicle speed sensor (VSS) | — | |
| W42 | OEM-A-37 | SPEEDUINO-A-18 | 0.5 | no route | A/C compressor switch | — |
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 (7)
| Severity | Code | Subject | Message |
|---|---|---|---|
| error | REQUIRED_UNMAPPED | OEM-A-17 | Required OEM function "MAF signal" (analog_in) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-A-34 | Required OEM function "Knock sensor 1" (knock_in) is not connected to the new ECU. |
| warn | LOAD_UNKNOWN | SPEEDUINO-A-15 | SPEEDUINO-A-15 "Proto area 2 (fan)" drives OEM-A-6 Fuel pump relay control (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | LOAD_UNKNOWN | SPEEDUINO-A-16 | SPEEDUINO-A-16 "Proto area 3 (fuel pump)" drives OEM-A-49 Secondary air injection relay control (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | LOAD_UNKNOWN | SPEEDUINO-A-36 | SPEEDUINO-A-36 "Idle 2 (3-wire idle)" drives OEM-A-9 Engine electronics relay control (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| info | NET_FAMILY | OEM-A-38 ↔ MAIN-R-COIL+ | OEM-A-38 "Ignition switch (run/start)" [digital_in] is wired to MAIN-R-COIL+ "Relay coil positive (ignition-switched +12V)" [power_in]. Switched supply used as the ignition-on sense. |
| info | UNMAPPED | OEM | 7 optional OEM pins are not mapped: OEM-A-21 Diagnostic L-line; OEM-A-36 Intake air temperature (IAT); OEM-A-39 A/C switch (cabin); OEM-A-43 Diagnostic K-line; OEM-A-51 MFA fuel-consumption signal; OEM-A-53 Idle air control valve (2nd); OEM-A-59 Mass airflow sensor (5th terminal) |
Accepted (1)
| Code | Subject | Reason | By |
|---|---|---|---|
| REQUIRED_UNMAPPED | OEM-A-54 | Battery-constant (memory) feed of the stock ECU: the new ECU has no such input, so it is not needed. | mapping-proposal |
Notes
Fit check: unconfirmed. Confirm these before building: - Trigger pattern for VW VR6 not found in the ECU's docs (No VR6 cam decoder.) - No knock input; the stock knock sensor would be unused - Only 4 ignition outputs for 6 cylinders: wasted spark (pair coils per firing order) - Only 4 injector outputs for 6 injectors: batch / semi-sequential injection Auto-mapped by auto_map() from the library pin data on 2026-10-20. Review every wire against both manuals before building. Open items: - OEM-A 34: Knock sensor 1: no free knock input on Speeduino Speeduino - OEM-A 17: MAF signal: no free maf/analog_0_5 on Speeduino Speeduino Not wired: - OEM-A 54: Battery constant (+12V): Speeduino Speeduino has no battery-constant memory input; not needed - OEM-A 53: Idle air control valve (2nd): no free low_side/relay_control/heater_low_side/ls_hs/injector on Speeduino Speeduino - OEM-A 51: MFA fuel-consumption signal: no free tacho/frequency_out/low_side/ls_hs on Speeduino Speeduino - OEM-A 36: Intake air temperature (IAT): no free thermistor/analog_0_5 on Speeduino Speeduino - OEM-A 39: A/C switch (cabin): no free switch_in/frequency_in/analog_0_5 on Speeduino Speeduino - OEM-A 21: Diagnostic L-line: no free k_line on Speeduino Speeduino - OEM-A 43: Diagnostic K-line: no free k_line on Speeduino Speeduino - OEM-A 59: Mass airflow sensor (5th terminal): no rule for class sensor_signal; wire by hand
Sources
| Reliability | Kind | Title | URL | Archive | Captured | SHA-256 |
|---|---|---|---|---|---|---|
| 4 | vendor_doc | Emtron SL4/SL6/SL8 pinout pages | https://docs.emtronaustralia.com.au/engine-management/wiring/index.html | archive | 2026-10-05 | e52b3da9996a |
| 4 | vendor_doc | Speeduino Manual (08/04/25) — V0.4 board IDC40 pinout & features | https://speeduino.com/Speeduino_manual.pdf | archive | 2026-10-05 | 21806bd29ef0 |
| 4 | vendor_doc | Speeduino wiki — V0.4 board & wiring (12v input, switched power) | https://wiki.speeduino.com/en/boards/V04 | — | — | — |
| 3 | forum | rusEFI Mazda Miata 2002 engine wiring | https://github.com/rusefi/rusefi/wiki/Mazda-Miata-2002 | archive | 2026-10-05 | cc3cae670408 |
| 2 | community_copy | a2resource: VR6/ABA Motronic M2.9 (OBD1) engine control unit pinout | http://www.a2resource.com/electrical/management/motronicvr6aba.html | — | — | — |