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MX-5 Miata NA8 1994-95 (BP-ZE, 1.8, OBD-I) → DTAFast T2i (auto)

MX-5 Miata NA8 1994-95 (BP-ZE, 1.8, OBD-I) — DTAFast — T2i
⚠ 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.

Statusdraft · not yet verified: nobody has reported building and running this harness
Open errors4: read the Findings page before cutting any wire
Size of the job31 wires · 6 connectors · 4 part lines
ToolsCrimp and extraction tools for each terminal family (see Connectors) · wire strippers · multimeter · heat gun + heat-shrink
Terminals3-1447221-4
Order of work1. 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.

WireFromToGaugeColourCutLabelCrimp ACrimp BPin APin BContinuity
W1OEM-1-BSP-14V-10.85☐☐☐☐☐☐☐
W2SP-14V-1T2I-C1-310.85☐☐☐☐☐☐☐
W3OEM-1-AT2I-C1-210.85☐☐☐☐☐☐☐
W4OEM-2-ASP-GND-10.85☐☐☐☐☐☐☐
W5OEM-2-BSP-GND-10.85☐☐☐☐☐☐☐
W6SP-GND-1T2I-C1-130.85☐☐☐☐☐☐☐
W7SP-GND-1T2I-C1-140.85☐☐☐☐☐☐☐
W8OEM-2-CSP-0V-10.5☐☐☐☐☐☐☐
W9OEM-2-DSP-0V-10.5☐☐☐☐☐☐☐
W10OEM-2-FSP-0V-10.5☐☐☐☐☐☐☐
W11SP-0V-1T2I-C1-280.5☐☐☐☐☐☐☐
W12SP-0V-1T2I-C1-290.5☐☐☐☐☐☐☐
W13OEM-2-KT2I-C1-270.5☐☐☐☐☐☐☐
W14OEM-2-ET2I-C1-190.5☐☐☐☐☐☐☐
W15OEM-2-GT2I-C1-120.5☐☐☐☐☐☐☐
W16OEM-1-GT2I-C1-30.5☐☐☐☐☐☐☐
W17OEM-1-HT2I-C1-60.5☐☐☐☐☐☐☐
W18OEM-1-JT2I-C1-10.5☐☐☐☐☐☐☐
W19OEM-1-RT2I-C1-100.5☐☐☐☐☐☐☐
W20OEM-2-ST2I-C1-180.5☐☐☐☐☐☐☐
W21OEM-2-TT2I-C1-260.5☐☐☐☐☐☐☐
W22OEM-2-OT2I-C1-200.5☐☐☐☐☐☐☐
W23OEM-2-MT2I-C1-220.5☐☐☐☐☐☐☐
W24OEM-2-NT2I-C1-230.5☐☐☐☐☐☐☐
W25OEM-2-QT2I-C1-240.5☐☐☐☐☐☐☐
W26OEM-2-PT2I-C1-320.5☐☐☐☐☐☐☐
W27OEM-1-MT2I-C1-110.5☐☐☐☐☐☐☐
W28OEM-1-CT2I-C1-300.5☐☐☐☐☐☐☐
W29OEM-1-PT2I-C1-250.5☐☐☐☐☐☐☐
W30OEM-1-QT2I-C1-330.5☐☐☐☐☐☐☐
W31OEM-1-VT2I-C1-340.5☐☐☐☐☐☐☐

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 AProbe BExpectWhyReading
1T2I-C1-21T2I-C1-13open (OL)+12 V supply must not touch power ground
2T2I-C1-21T2I-C1-28open (OL)+12 V supply must not touch sensor ground
3T2I-C1-31T2I-C1-13open (OL)+12 V supply must not touch power ground
4T2I-C1-31T2I-C1-28open (OL)+12 V supply must not touch sensor ground
5T2I-C1-13T2I-C1-27open (OL)power ground must not touch 5 V sensor reference
6T2I-C1-21T2I-C1-27open (OL)+12 V supply must not touch 5 V sensor reference
7T2I-C1-28T2I-C1-27open (OL)sensor ground must not touch 5 V sensor reference
8T2I-C1-31T2I-C1-27open (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

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Schematic

OEM-1OEM-2SP-0VSP-14VSP-GNDT2I-C1

Connectors

OEM-1

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
AConstant +12V—W3—0.85T2I-C1-21———
BECU power +14V (main relay)—W1—0.85SP-14V-1———
CStart signal—W28—0.5T2I-C1-30———
EMalfunction indicator lamp (MIL)————————
GIgnition 1 (coils 1+4, wasted spark)—W16—0.5T2I-C1-3———
HIgnition 2 (coils 2+3, wasted spark)—W17—0.5T2I-C1-6———
JA/C relay—W18—0.5T2I-C1-1———
MVehicle speed—W27—0.5T2I-C1-11———
PPower steering pressure switch—W29—0.5T2I-C1-25———
QA/C request—W30—0.5T2I-C1-33———
RCooling fan relay—W19—0.5T2I-C1-10———
VNeutral/clutch switch—W31—0.5T2I-C1-34———

OEM-2

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
APower ground—W4—0.85SP-GND-1———
BPower ground—W5—0.85SP-GND-1———
CSensor ground (E2)—W8—0.5SP-0V-1———
DSensor ground (E2)—W9—0.5SP-0V-1———
ECrank position (CAS NE)—W14—0.5T2I-C1-19———
FMAF ground—W10—0.5SP-0V-1———
GCam position (CAS G)—W15—0.5T2I-C1-12———
ITachometer output————————
K+5V sensor supply—W13—0.5T2I-C1-27———
MThrottle position (TPS)—W23—0.5T2I-C1-22———
NO2 sensor—W24—0.5T2I-C1-23———
OMass air flow (MAF)—W22—0.5T2I-C1-20———
PIntake air temperature (IAT)—W26—0.5T2I-C1-32———
QCoolant temperature (ECT)—W25—0.5T2I-C1-24———
RPRC solenoid (fuel pressure regulator)————————
SCondenser fan relay—W20—0.5T2I-C1-18———
TFuel pump relay—W21—0.5T2I-C1-26———
UInjector 1————————
VInjector 2————————
WISC solenoid————————
XEvap purge solenoid————————
YInjector 3————————
ZInjector 4————————

SP-0V

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
1——W8—0.5OEM-2-C———
1——W9—0.5OEM-2-D———
1——W10—0.5OEM-2-F———
1——W11—0.5T2I-C1-28———
1——W12—0.5T2I-C1-29———

SP-14V

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
1——W1—0.85OEM-1-B———
1——W2—0.85T2I-C1-31———

SP-GND

CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
1——W5—0.85OEM-2-B———
1——W6—0.85T2I-C1-13———
1——W7—0.85T2I-C1-14———
1——W4—0.85OEM-2-A———

T2I-C1

Mating face
T2I-C1-1 · PWM 11T2I-C1-2 · Lambda Nernst Voltage2T2I-C1-3 · Coil 13T2I-C1-4 · Lambda VGND4T2I-C1-5 · Lambda Pump Current5T2I-C1-6 · Coil 26T2I-C1-7 · Lambda Trim Resistor7T2I-C1-88T2I-C1-99T2I-C1-10 · PWM 210T2I-C1-11 · Digital 111T2I-C1-12 · Wheel 112T2I-C1-13 · Power Ground 113T2I-C1-14 · Power Ground 214T2I-C1-15 · Lambda Heater Negative15T2I-C1-16 · CAN High16T2I-C1-17 · CAN Low17T2I-C1-18 · PWM 318T2I-C1-19 · Crank19T2I-C1-20 · Analogue 120T2I-C1-21 · Permanent 12v21T2I-C1-22 · Analogue 222T2I-C1-23 · Analogue 323T2I-C1-24 · Thermistor 124T2I-C1-25 · Analogue 425T2I-C1-26 · PWM 426T2I-C1-27 · 5v Output27T2I-C1-28 · Sensor Ground28T2I-C1-29 · Sensor Ground29T2I-C1-30 · Digital 230T2I-C1-31 · Ignition 12v In31T2I-C1-32 · Thermistor 232T2I-C1-33 · Analogue 533T2I-C1-34 · Analogue 634
Wire side
T2I-C1-1 · PWM 11T2I-C1-2 · Lambda Nernst Voltage2T2I-C1-3 · Coil 13T2I-C1-4 · Lambda VGND4T2I-C1-5 · Lambda Pump Current5T2I-C1-6 · Coil 26T2I-C1-7 · Lambda Trim Resistor7T2I-C1-88T2I-C1-99T2I-C1-10 · PWM 210T2I-C1-11 · Digital 111T2I-C1-12 · Wheel 112T2I-C1-13 · Power Ground 113T2I-C1-14 · Power Ground 214T2I-C1-15 · Lambda Heater Negative15T2I-C1-16 · CAN High16T2I-C1-17 · CAN Low17T2I-C1-18 · PWM 318T2I-C1-19 · Crank19T2I-C1-20 · Analogue 120T2I-C1-21 · Permanent 12v21T2I-C1-22 · Analogue 222T2I-C1-23 · Analogue 323T2I-C1-24 · Thermistor 124T2I-C1-25 · Analogue 425T2I-C1-26 · PWM 426T2I-C1-27 · 5v Output27T2I-C1-28 · Sensor Ground28T2I-C1-29 · Sensor Ground29T2I-C1-30 · Digital 230T2I-C1-31 · Ignition 12v In31T2I-C1-32 · Thermistor 232T2I-C1-33 · Analogue 533T2I-C1-34 · Analogue 634
CavityFunctionSignalWireColourGauge (mm²)DestinationTerminalSealPlug
1PWM 1—W18—0.5OEM-1-J———
2Lambda Nernst Voltage————————
3Coil 1—W16—0.5OEM-1-G———
4Lambda VGND————————
5Lambda Pump Current————————
6Coil 2—W17—0.5OEM-1-H———
7Lambda Trim Resistor————————
8—————————
9—————————
10PWM 2—W19—0.5OEM-1-R———
11Digital 1—W27—0.5OEM-1-M———
12Wheel 1—W15—0.5OEM-2-G———
13Power Ground 1—W6—0.85SP-GND-1———
14Power Ground 2—W7—0.85SP-GND-1———
15Lambda Heater Negative————————
16CAN High————————
17CAN Low————————
18PWM 3—W20—0.5OEM-2-S———
19Crank—W14—0.5OEM-2-E———
20Analogue 1—W22—0.5OEM-2-O———
21Permanent 12v—W3—0.85OEM-1-A———
22Analogue 2—W23—0.5OEM-2-M———
23Analogue 3—W24—0.5OEM-2-N———
24Thermistor 1—W25—0.5OEM-2-Q———
25Analogue 4—W29—0.5OEM-1-P———
26PWM 4—W21—0.5OEM-2-T———
275v Output—W13—0.5OEM-2-K———
28Sensor Ground—W11—0.5SP-0V-1———
29Sensor Ground—W12—0.5SP-0V-1———
30Digital 2—W28—0.5OEM-1-C———
31Ignition 12v In—W2—0.85SP-14V-1———
32Thermistor 2—W26—0.5OEM-2-P———
33Analogue 5—W30—0.5OEM-1-Q———
34Analogue 6—W31—0.5OEM-1-V———

Pin map

OEM pointOEM functionOEM familyTarget pointTarget functionTarget familyWire colourEvidence
OEM-1-AConstant +12Vpower_inT2I-C1-21Permanent 12vpower_insingle_source
OEM-1-BECU power +14V (main relay)power_inT2I-C1-31Ignition 12v Inpower_insingle_source
OEM-1-CStart signaldigital_inT2I-C1-30Digital 2digital_insingle_source
OEM-1-EMalfunction indicator lamp (MIL)low_side_out———single_source
OEM-1-GIgnition 1 (coils 1+4, wasted spark)ignition_outT2I-C1-3Coil 1ignition_outsingle_source
OEM-1-HIgnition 2 (coils 2+3, wasted spark)ignition_outT2I-C1-6Coil 2ignition_outsingle_source
OEM-1-JA/C relaylow_side_outT2I-C1-1PWM 1low_side_outsingle_source
OEM-1-MVehicle speeddigital_inT2I-C1-11Digital 1digital_insingle_source
OEM-1-PPower steering pressure switchdigital_inT2I-C1-25Analogue 4analog_insingle_source
OEM-1-QA/C requestdigital_inT2I-C1-33Analogue 5analog_insingle_source
OEM-1-RCooling fan relaylow_side_outT2I-C1-10PWM 2low_side_outsingle_source
OEM-1-VNeutral/clutch switchdigital_inT2I-C1-34Analogue 6analog_insingle_source
OEM-2-APower groundgroundT2I-C1-13 + T2I-C1-14Power Ground 1 + Power Ground 2groundsingle_source
OEM-2-BPower groundgroundT2I-C1-13 + T2I-C1-14Power Ground 1 + Power Ground 2groundsingle_source
OEM-2-CSensor ground (E2)sensor_groundT2I-C1-28 + T2I-C1-29Sensor Ground + Sensor Groundsensor_groundcorroborated
OEM-2-DSensor ground (E2)sensor_groundT2I-C1-28 + T2I-C1-29Sensor Ground + Sensor Groundsensor_groundcorroborated
OEM-2-ECrank position (CAS NE)trigger_inT2I-C1-19Cranktrigger_insingle_source
OEM-2-FMAF groundsensor_groundT2I-C1-28 + T2I-C1-29Sensor Ground + Sensor Groundsensor_groundsingle_source
OEM-2-GCam position (CAS G)trigger_inT2I-C1-12Wheel 1digital_insingle_source
OEM-2-ITachometer outputtacho_out———single_source
OEM-2-K+5V sensor supplyvrefT2I-C1-275v Outputvrefsingle_source
OEM-2-MThrottle position (TPS)analog_inT2I-C1-22Analogue 2analog_insingle_source
OEM-2-NO2 sensorlambda_nb_inT2I-C1-23Analogue 3analog_insingle_source
OEM-2-OMass air flow (MAF)analog_inT2I-C1-20Analogue 1analog_insingle_source
OEM-2-PIntake air temperature (IAT)temp_inT2I-C1-32Thermistor 2temp_insingle_source
OEM-2-QCoolant temperature (ECT)temp_inT2I-C1-24Thermistor 1temp_insingle_source
OEM-2-RPRC solenoid (fuel pressure regulator)low_side_out———single_source
OEM-2-SCondenser fan relaylow_side_outT2I-C1-18PWM 3low_side_outsingle_source
OEM-2-TFuel pump relaylow_side_outT2I-C1-26PWM 4low_side_outsingle_source
OEM-2-UInjector 1injector_out———single_source
OEM-2-VInjector 2injector_out———single_source
OEM-2-WISC solenoidlow_side_out———single_source
OEM-2-XEvap purge solenoidlow_side_out———single_source
OEM-2-YInjector 3injector_out———single_source
OEM-2-ZInjector 4injector_out———single_source

Cut list

WireFromToGauge (mm²)ColourLengthSignalIdent
W1OEM-1-BSP-14V-10.85no routeECU power +14V (main relay)—
W2SP-14V-1T2I-C1-310.85no routeIgnition 12v In—
W3OEM-1-AT2I-C1-210.85no routeConstant +12V—
W4OEM-2-ASP-GND-10.85no routePower ground—
W5OEM-2-BSP-GND-10.85no routePower ground—
W6SP-GND-1T2I-C1-130.85no routePower Ground 1—
W7SP-GND-1T2I-C1-140.85no routePower Ground 2—
W8OEM-2-CSP-0V-10.5no routeSensor ground (E2)—
W9OEM-2-DSP-0V-10.5no routeSensor ground (E2)—
W10OEM-2-FSP-0V-10.5no routeMAF ground—
W11SP-0V-1T2I-C1-280.5no routeSensor Ground—
W12SP-0V-1T2I-C1-290.5no routeSensor Ground—
W13OEM-2-KT2I-C1-270.5no route+5V sensor supply—
W14OEM-2-ET2I-C1-190.5no routeCrank position (CAS NE)—
W15OEM-2-GT2I-C1-120.5no routeCam position (CAS G)—
W16OEM-1-GT2I-C1-30.5no routeIgnition 1 (coils 1+4, wasted spark)—
W17OEM-1-HT2I-C1-60.5no routeIgnition 2 (coils 2+3, wasted spark)—
W18OEM-1-JT2I-C1-10.5no routeA/C relay—
W19OEM-1-RT2I-C1-100.5no routeCooling fan relay—
W20OEM-2-ST2I-C1-180.5no routeCondenser fan relay—
W21OEM-2-TT2I-C1-260.5no routeFuel pump relay—
W22OEM-2-OT2I-C1-200.5no routeMass air flow (MAF)—
W23OEM-2-MT2I-C1-220.5no routeThrottle position (TPS)—
W24OEM-2-NT2I-C1-230.5no routeO2 sensor—
W25OEM-2-QT2I-C1-240.5no routeCoolant temperature (ECT)—
W26OEM-2-PT2I-C1-320.5no routeIntake air temperature (IAT)—
W27OEM-1-MT2I-C1-110.5no routeVehicle speed—
W28OEM-1-CT2I-C1-300.5no routeStart signal—
W29OEM-1-PT2I-C1-250.5no routePower steering pressure switch—
W30OEM-1-QT2I-C1-330.5no routeA/C request—
W31OEM-1-VT2I-C1-340.5no routeNeutral/clutch switch—

Bill of materials

CategoryPart numberManufacturerDescriptionQtyUnit
connector174515-6TEAMP Multilock .040/.070 hybrid 22-pin female harness plug (Miata NA/NB ECU)1.000ea
connector174516-6TEAMP Multilock .040/.070 hybrid 26-pin female harness plug (Miata NA/NB ECU)1.000ea
connector4-1437290-0TESuperseal 1.0 34-way plug, Key 11.000ea
terminal3-1447221-4TESuperseal 1.0 socket terminal, 20 AWG (0.5 sq mm)25.000ea

ECU setup sheet

RoleEngine refEngine signalSensorECU pointECU functionECU classSetup flag
No configured channels.

Findings

Open (10)

SeverityCodeSubjectMessage
errorREQUIRED_UNMAPPEDOEM-2-URequired OEM function "Injector 1" (injector_out) is not connected to the new ECU.
errorREQUIRED_UNMAPPEDOEM-2-VRequired OEM function "Injector 2" (injector_out) is not connected to the new ECU.
errorREQUIRED_UNMAPPEDOEM-2-YRequired OEM function "Injector 3" (injector_out) is not connected to the new ECU.
errorREQUIRED_UNMAPPEDOEM-2-ZRequired OEM function "Injector 4" (injector_out) is not connected to the new ECU.
warnDATASET_GAPT2i C12 of 34 cavities on T2i C1 have no pin data (8,9). Anything there is invisible to these checks.
warnNET_FAMILYOEM-1-P ↔ T2I-C1-25OEM-1-P "Power steering pressure switch" [digital_in] is wired to T2I-C1-25 "Analogue 4" [analog_in]. Analog and digital on one net. A switch on an analog input works with a pull-up and a threshold; an analog sensor on a digital input loses its value.
warnNET_FAMILYOEM-1-Q ↔ T2I-C1-33OEM-1-Q "A/C request" [digital_in] is wired to T2I-C1-33 "Analogue 5" [analog_in]. Analog and digital on one net. A switch on an analog input works with a pull-up and a threshold; an analog sensor on a digital input loses its value.
warnNET_FAMILYOEM-1-V ↔ T2I-C1-34OEM-1-V "Neutral/clutch switch" [digital_in] is wired to T2I-C1-34 "Analogue 6" [analog_in]. Analog and digital on one net. A switch on an analog input works with a pull-up and a threshold; an analog sensor on a digital input loses its value.
warnNET_FAMILYOEM-2-G ↔ T2I-C1-12OEM-2-G "Cam position (CAS G)" [trigger_in] is wired to T2I-C1-12 "Wheel 1" [digital_in]. Hall-type cam/speed signals can use a digital input if it handles the frequency; VR signals cannot.
infoUNMAPPEDOEM5 optional OEM pins are not mapped: OEM-1-E Malfunction indicator lamp (MIL); OEM-2-I Tachometer output; OEM-2-R PRC solenoid (fuel pressure regulator); OEM-2-W ISC solenoid; OEM-2-X Evap purge solenoid

Accepted (0)

CodeSubjectReasonBy

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: - OEM-2 U: Injector 1: no free injector output on DTAFast T2i - OEM-2 V: Injector 2: no free injector output on DTAFast T2i - OEM-2 Y: Injector 3: no free injector output on DTAFast T2i - OEM-2 Z: Injector 4: no free injector output on DTAFast T2i Not wired: - OEM-2 W: ISC solenoid: no free low_side/ls_hs/injector/hbridge rated ≥ 1.0 A on DTAFast T2i - OEM-1 E: Malfunction indicator lamp (MIL): no free low_side/ls_hs/injector/hbridge on DTAFast T2i - OEM-2 R: PRC solenoid (fuel pressure regulator): no free low_side/ls_hs/injector/hbridge on DTAFast T2i - OEM-2 X: Evap purge solenoid: no free low_side/ls_hs/injector/hbridge on DTAFast T2i - OEM-2 I: Tachometer output: no free tacho/frequency_out/low_side/ls_hs on DTAFast T2i

Sources

ReliabilityKindTitleURLArchiveCapturedSHA-256
4vendor_docDTAFast T2i ECU wiring diagramhttps://cdn.shopify.com/s/files/1/0848/7508/4108/files/T2i_Wiring-Diagram.pdf?v=1728571341———
4vendor_docLink G4X MX5X install manual (NA 1.6/1.8)https://linkecu.com/documentation/MX5X.pdfarchive2026-10-05b7f730de9f6e
2expert_reportJustin Barrera — Miata NA/NB wiring corrections————
2community_copyrusefi wiki: 1994 Mazda Miata 1.8 (NA8) ECU pinouthttps://github.com/rusefi/rusefi/wiki/Mazda-Miata-1994—2026-10-08075801b907f4