Miata NB2 → K-CI v1 (chassis adapter)
Drawn by Michael Gnankou · Rev 0 · proposal · 2026-10-04
Revisions
| Rev | Label | By | Date |
|---|---|---|---|
| No revisions yet. | |||
Schematic
Connectors
KCI
Mating face
Wire side
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | C1 | — | 0.5 | PCM-4-AG | — | — | — |
| 2 | — | — | C2 | — | 0.5 | PCM-4-AF | — | — | — |
| 3 | — | — | — | — | — | — | — | — | — |
| 4 | — | — | C3 | — | 0.5 | PCM-3-A | — | — | — |
| 5 | — | — | C4 | — | 0.5 | PCM-3-B | — | — | — |
| 6 | — | — | C5 | — | 0.5 | PCM-3-O | — | — | — |
| 7 | — | — | C6 | — | 0.5 | PCM-2-R | — | — | — |
| 8 | — | — | — | — | — | — | — | — | — |
| 9 | — | — | — | — | — | — | — | — | — |
| 10 | — | — | — | — | — | — | — | — | — |
| 11 | — | — | C7 | — | 0.5 | PCM-2-B | — | — | — |
| 12 | — | — | C8 | — | 0.5 | PCM-2-M | — | — | — |
| 13 | — | — | C9 | — | 0.5 | PCM-2-K | — | — | — |
| 14 | — | — | C10 | — | 0.5 | PCM-4-F | — | — | — |
| 15 | — | — | C11 | — | 0.5 | PCM-4-I | — | — | — |
| 16 | — | — | C12 | — | 0.5 | PCM-4-H | — | — | — |
| 17 | — | — | C13 | — | 0.5 | PCM-4-B | — | — | — |
| 18 | — | — | C14 | — | 0.5 | PCM-3-T | — | — | — |
| 19 | — | — | — | — | — | — | — | — | — |
| 20 | — | — | — | — | — | — | — | — | — |
| 21 | — | — | — | — | — | — | — | — | — |
| 22 | — | — | — | — | — | — | — | — | — |
| 23 | — | — | — | — | — | — | — | — | — |
| 24 | — | — | — | — | — | — | — | — | — |
| 25 | — | — | — | — | — | — | — | — | — |
| 26 | — | — | — | — | — | — | — | — | — |
| 27 | — | — | — | — | — | — | — | — | — |
| 28 | — | — | — | — | — | — | — | — | — |
PCM-2
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Injector 1 | — | — | — | — | — | — | — | — |
| B | Cooling fan relay | — | C7 | — | 0.5 | KCI-11 | — | — | — |
| C | Condenser fan relay | — | — | — | — | — | — | — | — |
| D | Injector 2 | — | — | — | — | — | — | — | — |
| E | EGR valve | — | — | — | — | — | — | — | — |
| F | EGR valve | — | — | — | — | — | — | — | — |
| G | Injector 3 | — | — | — | — | — | — | — | — |
| H | EGR valve | — | — | — | — | — | — | — | — |
| I | EGR valve | — | — | — | — | — | — | — | — |
| J | Injector 4 | — | — | — | — | — | — | — | — |
| K | A/C clutch relay | — | C9 | — | 0.5 | KCI-13 | — | — | — |
| M | Fuel pump relay | — | C8 | — | 0.5 | KCI-12 | — | — | — |
| N | VTCS solenoid (intake butterflies) | — | — | — | — | — | — | — | — |
| P | ISC valve +14V feed | — | — | — | — | — | — | — | — |
| Q | ISC valve low side | — | — | — | — | — | — | — | — |
| R | Malfunction indicator lamp (MIL) | — | C6 | — | 0.5 | KCI-7 | — | — | — |
PCM-3
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Power ground | — | C3 | — | 0.5 | KCI-4 | — | — | — |
| B | Power ground | — | C4 | — | 0.5 | KCI-5 | — | — | — |
| D | EGR boost solenoid | — | — | — | — | — | — | — | — |
| E | Charcoal canister purge | — | — | — | — | — | — | — | — |
| F | Ignition 1 (coils 1+4, wasted spark) | — | — | — | — | — | — | — | — |
| H | Main relay | — | — | — | — | — | — | — | — |
| I | Ignition 2 (coils 2+3, wasted spark) | — | — | — | — | — | — | — | — |
| J | Front O2 heater | — | — | — | — | — | — | — | — |
| M | Alternator control | — | — | — | — | — | — | — | — |
| O | Tachometer output | — | C5 | — | 0.5 | KCI-6 | — | — | — |
| P | Rear O2 heater | — | — | — | — | — | — | — | — |
| S | Immobiliser | — | — | — | — | — | — | — | — |
| T | Vehicle speed | — | C14 | — | 0.5 | KCI-18 | — | — | — |
| U | Charge lamp | — | — | — | — | — | — | — | — |
| V | Cam position (CMP) | — | — | — | — | — | — | — | — |
| Y | Crank position (CKP) | — | — | — | — | — | — | — | — |
PCM-4
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A | Power ground | — | — | — | — | — | — | — | — |
| AA | Rear O2 signal | — | — | — | — | — | — | — | — |
| AD | Fuel level | — | — | — | — | — | — | — | — |
| AF | ECU power +14V (main relay) | — | C2 | — | 0.5 | KCI-2 | — | — | — |
| AG | Constant +12V | — | C1 | — | 0.5 | KCI-1 | — | — | — |
| B | Brake switch | — | C13 | — | 0.5 | KCI-17 | — | — | — |
| C | Power steering pressure switch | — | — | — | — | — | — | — | — |
| D | VVT oil-control solenoid | — | — | — | — | — | — | — | — |
| F | A/C request | — | C10 | — | 0.5 | KCI-14 | — | — | — |
| H | Neutral switch | — | C12 | — | 0.5 | KCI-16 | — | — | — |
| I | Clutch switch | — | C11 | — | 0.5 | KCI-15 | — | — | — |
| J | VTCS vacuum switch | — | — | — | — | — | — | — | — |
| L | +5V sensor supply | — | — | — | — | — | — | — | — |
| M | Knock sensor | — | — | — | — | — | — | — | — |
| N | Intake air temperature (IAT) | — | — | — | — | — | — | — | — |
| O | Signal ground | — | — | — | — | — | — | — | — |
| P | Coolant temperature (ECT) | — | — | — | — | — | — | — | — |
| V | Throttle position (TPS) | — | — | — | — | — | — | — | — |
| W | Front O2 signal | — | — | — | — | — | — | — | — |
| X | Mass air flow (MAF) | — | — | — | — | — | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| PCM-2-A | Injector 1 | injector_out | — | — | — | single_source | |
| PCM-2-B | Cooling fan relay | low_side_out | — | — | — | single_source | |
| PCM-2-C | Condenser fan relay | low_side_out | — | — | — | single_source | |
| PCM-2-D | Injector 2 | injector_out | — | — | — | single_source | |
| PCM-2-E | EGR valve | low_side_out | — | — | — | single_source | |
| PCM-2-F | EGR valve | low_side_out | — | — | — | single_source | |
| PCM-2-G | Injector 3 | injector_out | — | — | — | single_source | |
| PCM-2-H | EGR valve | low_side_out | — | — | — | single_source | |
| PCM-2-I | EGR valve | low_side_out | — | — | — | single_source | |
| PCM-2-J | Injector 4 | injector_out | — | — | — | single_source | |
| PCM-2-K | A/C clutch relay | low_side_out | — | — | — | single_source | |
| PCM-2-M | Fuel pump relay | low_side_out | — | — | — | single_source | |
| PCM-2-N | VTCS solenoid (intake butterflies) | low_side_out | — | — | — | single_source | |
| PCM-2-P | ISC valve +14V feed | power_in | — | — | — | single_source | |
| PCM-2-Q | ISC valve low side | low_side_out | — | — | — | single_source | |
| PCM-2-R | Malfunction indicator lamp (MIL) | low_side_out | — | — | — | single_source | |
| PCM-3-A | Power ground | ground | — | — | — | single_source | |
| PCM-3-B | Power ground | ground | — | — | — | single_source | |
| PCM-3-D | EGR boost solenoid | low_side_out | — | — | — | single_source | |
| PCM-3-E | Charcoal canister purge | low_side_out | — | — | — | single_source | |
| PCM-3-F | Ignition 1 (coils 1+4, wasted spark) | ignition_out | — | — | — | single_source | |
| PCM-3-H | Main relay | low_side_out | — | — | — | single_source | |
| PCM-3-I | Ignition 2 (coils 2+3, wasted spark) | ignition_out | — | — | — | single_source | |
| PCM-3-J | Front O2 heater | low_side_out | — | — | — | single_source | |
| PCM-3-M | Alternator control | low_side_out | — | — | — | single_source | |
| PCM-3-O | Tachometer output | tacho_out | — | — | — | single_source | |
| PCM-3-P | Rear O2 heater | low_side_out | — | — | — | single_source | |
| PCM-3-S | Immobiliser | digital_in | — | — | — | single_source | |
| PCM-3-T | Vehicle speed | digital_in | — | — | — | single_source | |
| PCM-3-U | Charge lamp | low_side_out | — | — | — | single_source | |
| PCM-3-V | Cam position (CMP) | trigger_in | — | — | — | single_source | |
| PCM-3-Y | Crank position (CKP) | trigger_in | — | — | — | single_source | |
| PCM-4-A | Power ground | ground | — | — | — | single_source | |
| PCM-4-AA | Rear O2 signal | lambda_nb_in | — | — | — | single_source | |
| PCM-4-AD | Fuel level | analog_in | — | — | — | single_source | |
| PCM-4-AF | ECU power +14V (main relay) | power_in | — | — | — | single_source | |
| PCM-4-AG | Constant +12V | power_in | — | — | — | single_source | |
| PCM-4-B | Brake switch | digital_in | — | — | — | single_source | |
| PCM-4-C | Power steering pressure switch | digital_in | — | — | — | single_source | |
| PCM-4-D | VVT oil-control solenoid | low_side_out | — | — | — | single_source | |
| PCM-4-F | A/C request | digital_in | — | — | — | single_source | |
| PCM-4-H | Neutral switch | digital_in | — | — | — | single_source | |
| PCM-4-I | Clutch switch | digital_in | — | — | — | single_source | |
| PCM-4-J | VTCS vacuum switch | digital_in | — | — | — | single_source | |
| PCM-4-L | +5V sensor supply | vref | — | — | — | single_source | |
| PCM-4-M | Knock sensor | knock_in | — | — | — | single_source | |
| PCM-4-N | Intake air temperature (IAT) | temp_in | — | — | — | single_source | |
| PCM-4-O | Signal ground | sensor_ground | — | — | — | single_source | |
| PCM-4-P | Coolant temperature (ECT) | temp_in | — | — | — | single_source | |
| PCM-4-V | Throttle position (TPS) | analog_in | — | — | — | single_source | |
| PCM-4-W | Front O2 signal | lambda_nb_in | — | — | — | single_source | |
| PCM-4-X | Mass air flow (MAF) | analog_in | — | — | — | single_source |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| C1 | KCI-1 | PCM-4-AG | 0.5 | no route | Constant +12V | — | |
| C2 | KCI-2 | PCM-4-AF | 0.5 | no route | ECU power +14V (main relay) | — | |
| C3 | KCI-4 | PCM-3-A | 0.5 | no route | Power ground | — | |
| C4 | KCI-5 | PCM-3-B | 0.5 | no route | Power ground | — | |
| C5 | KCI-6 | PCM-3-O | 0.5 | no route | Tachometer output | — | |
| C6 | KCI-7 | PCM-2-R | 0.5 | no route | Malfunction indicator lamp (MIL) | — | |
| C7 | KCI-11 | PCM-2-B | 0.5 | no route | Cooling fan relay | — | |
| C8 | KCI-12 | PCM-2-M | 0.5 | no route | Fuel pump relay | — | |
| C9 | KCI-13 | PCM-2-K | 0.5 | no route | A/C clutch relay | — | |
| C10 | KCI-14 | PCM-4-F | 0.5 | no route | A/C request | — | |
| C11 | KCI-15 | PCM-4-I | 0.5 | no route | Clutch switch | — | |
| C12 | KCI-16 | PCM-4-H | 0.5 | no route | Neutral switch | — | |
| C13 | KCI-17 | PCM-4-B | 0.5 | no route | Brake switch | — | |
| C14 | KCI-18 | PCM-3-T | 0.5 | no route | Vehicle speed | — |
Bill of materials
| Category | Part number | Manufacturer | Description | Qty | Unit |
|---|---|---|---|---|---|
| connector | K-CI-01 | hx | K-swap chassis interface, 28-way (app-defined; physical part TBD per D2) | 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 (0)
| Severity | Code | Subject | Message |
|---|
Accepted (19)
| Code | Subject | Reason | By |
|---|---|---|---|
| REQUIRED_UNMAPPED | PCM-2-A | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-2-D | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-2-G | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-2-J | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-3-A | Wired through K-CI to the engine harness (seed 0039), which holds the aftermarket ECU; hx.validate() scopes nets to one harness, so the cross-harness reach is verified in the engine harness, not here. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-3-B | Wired through K-CI to the engine harness (seed 0039), which holds the aftermarket ECU; hx.validate() scopes nets to one harness, so the cross-harness reach is verified in the engine harness, not here. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-3-F | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-3-I | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-3-V | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-3-Y | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-4-A | NB2 third power ground; the K-CI v1 interface carries two main grounds (gnd1/gnd2), so this one returns at the chassis rather than through the adapter. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-4-AF | Wired through K-CI to the engine harness (seed 0039), which holds the aftermarket ECU; hx.validate() scopes nets to one harness, so the cross-harness reach is verified in the engine harness, not here. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-4-AG | Wired through K-CI to the engine harness (seed 0039), which holds the aftermarket ECU; hx.validate() scopes nets to one harness, so the cross-harness reach is verified in the engine harness, not here. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-4-L | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-4-O | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-4-P | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-4-V | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| REQUIRED_UNMAPPED | PCM-4-X | BP-Z3 engine removed in the K24/K20 swap; this function is wired directly from the K-series engine layer (seed 0039), so the Miata PCM engine pin is intentionally dead. | mapping-proposal |
| UNMAPPED | PCM | Optional NB2 functions not wired: EGR/VTCS/ISC (removed with the BP-Z3 engine), condenser fan (2C — assign to a spare K-CI pin), immobiliser, A/C charge lamp, fuel level, rear O2, and VVT. | mapping-proposal |
Notes
Maps the K-CI v1 chassis interface (28-way K-CI-01) to the Miata NB2 factory PCM chassis pins. 14 chassis circuits wired; engine pins waived (BP-Z3 removed, K-series engine layer wires them directly). DBW/CAN/gauge-sender pins are not applicable to a cable-throttle NB2 and are left open.
Sources
| Reliability | Kind | Title | URL |
|---|---|---|---|
| 4 | vendor_doc | Link G4X MX5NB2X install manual (NB2 2001-05) | https://linkecu.com/documentation/MX5XNB2.pdf |