MX-5 Miata Mazdaspeed 2004-05 (BP-ZET turbo, no VVT) → Motorsport Electronics ME221 (auto)
Before you start
Not confident with automotive wiring? Have a professional harness builder or tuner do it, or check your work before first power-up. A wiring mistake can damage the ECU, the engine or the car, or start a fire.
| 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 · 2 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-4-D | ME221-C1-67 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | OEM-4-E | ME221-C1-68 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | OEM-4-AE | ME221-C1-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | OEM-4-R | ME221-C1-86 | 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
ME221-C1
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | COIL 4 | — | — | — | — | — | — | — | — |
| 10 | GROUND CHASSIS | — | — | — | — | — | — | — | — |
| 12 | LOW SIDE 2 | — | — | — | — | — | — | — | — |
| 14 | LSU +12V | — | — | — | — | — | — | — | — |
| 15 | IGN +12V | — | — | — | — | — | — | — | — |
| 16 | LSU HEATER -VE | — | — | — | — | — | — | — | — |
| 17 | ANA VOLT 3 | — | — | — | — | — | — | — | — |
| 18 | ANA VOLT 4 | — | — | — | — | — | — | — | — |
| 19 | LSU UN | — | — | — | — | — | — | — | — |
| 2 | COIL 3 | — | — | — | — | — | — | — | — |
| 20 | LSU VM | — | — | — | — | — | — | — | — |
| 21 | CAN 1 HIGH | — | — | — | — | — | — | — | — |
| 22 | CAM A VR+ | — | — | — | — | — | — | — | — |
| 23 | CAM A VR- | — | — | — | — | — | — | — | — |
| 24 | SERIAL 1 GROUND | — | — | — | — | — | — | — | — |
| 25 | SERIAL 1 TX | — | — | — | — | — | — | — | — |
| 26 | ANA VOLT 1 | — | W3 | — | 0.5 | OEM-4-AE | — | — | — |
| 3 | INJECTOR 4 | — | — | — | — | — | — | — | — |
| 31 | COIL 2 | — | — | — | — | — | — | — | — |
| 32 | COIL 1 | — | — | — | — | — | — | — | — |
| 33 | INJECTOR 3 | — | — | — | — | — | — | — | — |
| 35 | USB D+ | — | — | — | — | — | — | — | — |
| 36 | USB D- | — | — | — | — | — | — | — | — |
| 37 | LOW SIDE RELAY 11 | — | — | — | — | — | — | — | — |
| 38 | USB VBUS | — | — | — | — | — | — | — | — |
| 39 | LOW SIDE 6 | — | — | — | — | — | — | — | — |
| 4 | INJECTOR 2 | — | — | — | — | — | — | — | — |
| 41 | USB GROUND | — | — | — | — | — | — | — | — |
| 42 | LOW SIDE RELAY 12 | — | — | — | — | — | — | — | — |
| 43 | LOW SIDE RELAY 14 | — | — | — | — | — | — | — | — |
| 44 | LOW SIDE 4 | — | — | — | — | — | — | — | — |
| 45 | 5V REF | — | — | — | — | — | — | — | — |
| 46 | 5V REF | — | — | — | — | — | — | — | — |
| 49 | LSU IA | — | — | — | — | — | — | — | — |
| 50 | LSU IP | — | — | — | — | — | — | — | — |
| 51 | CAN 1 LOW | — | — | — | — | — | — | — | — |
| 52 | SENSORS GROUND | — | — | — | — | — | — | — | — |
| 53 | KNOCK 1 SIGNAL | — | — | — | — | — | — | — | — |
| 55 | SERIAL 1 RX | — | — | — | — | — | — | — | — |
| 56 | ANA VOLT 2 | — | — | — | — | — | — | — | — |
| 57 | ANA TEMP 2 | — | — | — | — | — | — | — | — |
| 6 | DIG_IN 1 | — | — | — | — | — | — | — | — |
| 61 | GROUND | — | — | — | — | — | — | — | — |
| 63 | INJECTOR 1 | — | — | — | — | — | — | — | — |
| 64 | VBAT | — | — | — | — | — | — | — | — |
| 67 | Stepper 1 / A1 | — | W1 | — | 0.5 | OEM-4-D | — | — | — |
| 68 | Stepper 2 / A2 | — | W2 | — | 0.5 | OEM-4-E | — | — | — |
| 69 | LOW SIDE 5 | — | — | — | — | — | — | — | — |
| 7 | DIG_IN 2 | — | — | — | — | — | — | — | — |
| 70 | Stepper 3 / B1 | — | — | — | — | — | — | — | — |
| 71 | Stepper 4 / B2 | — | — | — | — | — | — | — | — |
| 72 | LOW SIDE RELAY 13 | — | — | — | — | — | — | — | — |
| 73 | LOW SIDE 1 | — | — | — | — | — | — | — | — |
| 74 | LOW SIDE 3 | — | — | — | — | — | — | — | — |
| 76 | 5V REF | — | — | — | — | — | — | — | — |
| 79 | TACHOMETER | — | — | — | — | — | — | — | — |
| 80 | CRANK VR- | — | — | — | — | — | — | — | — |
| 81 | CRANK VR+ | — | — | — | — | — | — | — | — |
| 84 | Sensor Ground | — | — | — | — | — | — | — | — |
| 86 | ANA TEMP 1 | — | W4 | — | 0.5 | OEM-4-R | — | — | — |
| 89 | GROUND | — | — | — | — | — | — | — | — |
| 90 | GROUND | — | — | — | — | — | — | — | — |
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 | ME221-C1-26 | — | — | — |
| D | Boost control solenoid (turbo) | — | W1 | — | 0.5 | ME221-C1-67 | — | — | — |
| E | Boost control solenoid (turbo) | — | W2 | — | 0.5 | ME221-C1-68 | — | — | — |
| R | Intake air temperature 2 (IAT2, turbo) | — | W4 | — | 0.5 | ME221-C1-86 | — | — | — |
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 | ME221-C1-26 | ANA VOLT 1 | analog_in | LY | single_source |
| OEM-4-D | Boost control solenoid (turbo) | high_side_out | ME221-C1-67 | Stepper 1 / A1 | hbridge_out | Y | single_source |
| OEM-4-E | Boost control solenoid (turbo) | high_side_out | ME221-C1-68 | Stepper 2 / A2 | hbridge_out | Y | single_source |
| OEM-4-R | Intake air temperature 2 (IAT2, turbo) | temp_in | ME221-C1-86 | ANA TEMP 1 | temp_in | VY | single_source |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-4-D | ME221-C1-67 | 0.5 | no route | Boost control solenoid (turbo) | — | |
| W2 | OEM-4-E | ME221-C1-68 | 0.5 | no route | Boost control solenoid (turbo) | — | |
| W3 | OEM-4-AE | ME221-C1-26 | 0.5 | no route | BARO/MAP sensor (turbo boost pressure) | — | |
| W4 | OEM-4-R | ME221-C1-86 | 0.5 | no route | Intake air temperature 2 (IAT2, turbo) | — |
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 (9)
| Severity | Code | Subject | Message |
|---|---|---|---|
| error | PHYS_REQUIRED_OPEN | ME221-C1-10 | ME221-C1-10 "GROUND CHASSIS" is required but not wired. |
| error | PHYS_REQUIRED_OPEN | ME221-C1-15 | ME221-C1-15 "IGN +12V" is required but not wired. |
| error | PHYS_REQUIRED_OPEN | ME221-C1-61 | ME221-C1-61 "GROUND" is required but not wired. |
| error | PHYS_REQUIRED_OPEN | ME221-C1-64 | ME221-C1-64 "VBAT" is required but not wired. |
| error | PHYS_REQUIRED_OPEN | ME221-C1-89 | ME221-C1-89 "GROUND" is required but not wired. |
| error | PHYS_REQUIRED_OPEN | ME221-C1-90 | ME221-C1-90 "GROUND" is required but not wired. |
| warn | NET_FAMILY | OEM-4-D ↔ ME221-C1-67 | OEM-4-D "Boost control solenoid (turbo)" [high_side_out] is wired to ME221-C1-67 "Stepper 1 / A1" [hbridge_out]. A half-bridge can act as a high-side switch only if configured that way. |
| warn | NET_FAMILY | OEM-4-E ↔ ME221-C1-68 | OEM-4-E "Boost control solenoid (turbo)" [high_side_out] is wired to ME221-C1-68 "Stepper 2 / A2" [hbridge_out]. A half-bridge can act as a high-side switch only if configured that way. |
| 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 - ME221-C1 10: GROUND CHASSIS: required by Motorsport Electronics ME221 but no stock pin feeds it; wire by hand - ME221-C1 15: IGN +12V: required by Motorsport Electronics ME221 but no stock pin feeds it; wire by hand - ME221-C1 61: GROUND: required by Motorsport Electronics ME221 but no stock pin feeds it; wire by hand - ME221-C1 64: VBAT: required by Motorsport Electronics ME221 but no stock pin feeds it; wire by hand - ME221-C1 89: GROUND: required by Motorsport Electronics ME221 but no stock pin feeds it; wire by hand - ME221-C1 90: GROUND: required by Motorsport Electronics ME221 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 Motorsport Electronics ME221
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 | Motorsport Electronics GEN2 ME221/ME360/ME442 wire-in pinout | https://motorsport-electronics.co.uk/onlinehelp/html/ME442ME360ME221GEN2Wire-InPinout.html | — | — | — |