VW Golf Mk4 1.8T 20v (AUM, Bosch ME7.5) DBW → DTAFast T2i (auto)
VW Golf Mk4 1.8T 20v (AUM, Bosch ME7.5) DBW — DTAFast — T2i
⚠ 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 | 11: read the Findings page before cutting any wire |
| Size of the job | 44 wires · 6 connectors · 2 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-T121-121 | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | OEM-T121-21 | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | SP-14V-1 | T2I-C1-31 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | OEM-T121-62 | T2I-C1-21 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | OEM-T121-1 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | OEM-T121-2 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | SP-GND-1 | T2I-C1-13 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | SP-GND-1 | T2I-C1-14 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | OEM-T121-108 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | OEM-T121-29 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | OEM-T121-34 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | OEM-T121-36 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-T121-90 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-T121-91 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | SP-0V-1 | T2I-C1-28 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | SP-0V-1 | T2I-C1-29 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-T121-72 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-T121-73 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-T121-83 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-T121-98 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-T121-99 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | SP-5V1-1 | T2I-C1-27 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-T121-82 | T2I-C1-19 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-T121-86 | T2I-C1-12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-T121-102 | T2I-C1-3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-T121-95 | T2I-C1-6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-T121-53 | T2I-C1-20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-T121-101 | T2I-C1-22 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-T121-33 | T2I-C1-23 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-T121-84 | T2I-C1-25 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W31 | OEM-T121-35 | T2I-C1-33 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W32 | OEM-T121-92 | T2I-C1-34 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W33 | OEM-T121-93 | T2I-C1-24 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W34 | OEM-T121-65 | T2I-C1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W35 | OEM-T121-66 | T2I-C1-10 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W36 | OEM-T121-5 | T2I-C1-15 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W37 | OEM-T121-63 | T2I-C1-18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W38 | OEM-T121-104 | T2I-C1-26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W39 | OEM-T121-51 | T2I-C1-5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W40 | OEM-T121-70 | T2I-C1-2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W41 | OEM-T121-85 | T2I-C1-32 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W42 | OEM-T121-54 | T2I-C1-11 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W43 | OEM-T121-60 | T2I-C1-16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W44 | OEM-T121-58 | T2I-C1-17 | 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 | T2I-C1-13 | T2I-C1-21 | open (OL) | power ground must not touch +12 V supply | |
| 2 | T2I-C1-13 | T2I-C1-27 | open (OL) | power ground must not touch 5 V sensor reference | |
| 3 | T2I-C1-13 | T2I-C1-31 | open (OL) | power ground must not touch +12 V supply | |
| 4 | T2I-C1-21 | T2I-C1-27 | open (OL) | +12 V supply must not touch 5 V sensor reference | |
| 5 | T2I-C1-28 | T2I-C1-21 | open (OL) | sensor ground must not touch +12 V supply | |
| 6 | T2I-C1-28 | T2I-C1-27 | open (OL) | sensor ground must not touch 5 V sensor reference | |
| 7 | T2I-C1-28 | T2I-C1-31 | open (OL) | sensor ground must not touch +12 V supply | |
| 8 | T2I-C1-31 | T2I-C1-27 | open (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
| Rev | Label | By | Date |
|---|---|---|---|
| No revisions yet. | |||
Schematic
Connectors
OEM-T121
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | ECU ground | — | W5 | — | 0.85 | SP-GND-1 | — | — | — |
| 101 | Boost pressure sensor (G31) | — | W28 | — | 0.5 | T2I-C1-22 | — | — | — |
| 102 | Ignition coil 1 (N127) | — | W25 | — | 0.5 | T2I-C1-3 | — | — | — |
| 103 | Ignition coil 3 (N158) | — | — | — | — | — | — | — | — |
| 104 | Boost control solenoid (N75) | — | W38 | — | 0.5 | T2I-C1-26 | — | — | — |
| 105 | Diverter valve (N249) | — | — | — | — | — | — | — | — |
| 106 | Knock sensor 1 (G61) | — | — | — | — | — | — | — | — |
| 107 | Knock sensor 2 (G66) | — | — | — | — | — | — | — | — |
| 108 | Sensor ground | — | W9 | — | 0.5 | SP-0V-1 | — | — | — |
| 115 | VVT camshaft adjustment valve (N205) | — | — | — | — | — | — | — | — |
| 117 | Throttle motor G186 (+) | — | — | — | — | — | — | — | — |
| 118 | Throttle motor G186 (−) | — | — | — | — | — | — | — | — |
| 121 | ECM + coil power (J271 relay feed) | — | W1 | — | 0.85 | SP-14V-1 | — | — | — |
| 2 | ECU ground | — | W6 | — | 0.85 | SP-GND-1 | — | — | — |
| 21 | ECM power (J271 relay feed) | — | W2 | — | 0.85 | SP-14V-1 | — | — | — |
| 27 | MAF sensor supply (G70) | — | — | — | — | — | — | — | — |
| 29 | MAF sensor ground (G70) | — | W10 | — | 0.5 | SP-0V-1 | — | — | — |
| 3 | Ignition switch +12V (term 15) | — | — | — | — | — | — | — | — |
| 33 | Accelerator pedal position 1 (G79) | — | W29 | — | 0.5 | T2I-C1-23 | — | — | — |
| 34 | Accelerator pedal position 1 ground (G79) | — | W11 | — | 0.5 | SP-0V-1 | — | — | — |
| 35 | Accelerator pedal position 2 (G185) | — | W31 | — | 0.5 | T2I-C1-33 | — | — | — |
| 36 | Accelerator pedal position 2 ground (G185) | — | W12 | — | 0.5 | SP-0V-1 | — | — | — |
| 37 | Engine speed signal (tacho to cluster) | — | — | — | — | — | — | — | — |
| 43 | K-line diagnostics (OBD pin 7) | — | — | — | — | — | — | — | — |
| 47 | Check engine light (MIL) | — | — | — | — | — | — | — | — |
| 48 | EPC warning light | — | — | — | — | — | — | — | — |
| 5 | Wideband lambda heater (Z19) | — | W36 | — | 0.5 | T2I-C1-15 | — | — | — |
| 51 | Wideband lambda pump (G39) | — | W39 | — | 0.5 | T2I-C1-5 | — | — | — |
| 52 | Wideband lambda pump (G39) | — | — | — | — | — | — | — | — |
| 53 | MAF sensor signal (G70) | — | W27 | — | 0.5 | T2I-C1-20 | — | — | — |
| 54 | Road speed signal (VSS) | — | W42 | — | 0.5 | T2I-C1-11 | — | — | — |
| 58 | CAN bus low | — | W44 | — | 0.5 | T2I-C1-17 | — | — | — |
| 60 | CAN bus high | — | W43 | — | 0.5 | T2I-C1-16 | — | — | — |
| 62 | Battery constant +12V (term 30) | — | W4 | — | 0.85 | T2I-C1-21 | — | — | — |
| 63 | Post-cat lambda heater (Z29) | — | W37 | — | 0.5 | T2I-C1-18 | — | — | — |
| 64 | EVAP canister valve (N80) | — | — | — | — | — | — | — | — |
| 65 | Fuel pump relay control | — | W34 | — | 0.5 | T2I-C1-1 | — | — | — |
| 66 | Secondary-air pump relay (J299) | — | W35 | — | 0.5 | T2I-C1-10 | — | — | — |
| 68 | Post-cat lambda signal (G130) | — | — | — | — | — | — | — | — |
| 69 | Post-cat lambda signal (G130) | — | — | — | — | — | — | — | — |
| 70 | Wideband lambda Nernst signal (G39) | — | W40 | — | 0.5 | T2I-C1-2 | — | — | — |
| 71 | Wideband lambda Nernst signal (G39) | — | — | — | — | — | — | — | — |
| 72 | Accelerator pedal position 1 5V supply (G79) | — | W17 | — | 0.5 | SP-5V1-1 | — | — | — |
| 73 | Accelerator pedal position 2 5V supply (G185) | — | W18 | — | 0.5 | SP-5V1-1 | — | — | — |
| 82 | Crank position sensor (G28) | — | W23 | — | 0.5 | T2I-C1-19 | — | — | — |
| 83 | Throttle position sensor 5V supply (G187/G188) | — | W19 | — | 0.5 | SP-5V1-1 | — | — | — |
| 84 | Throttle position sensor 1 (G187) | — | W30 | — | 0.5 | T2I-C1-25 | — | — | — |
| 85 | Intake air temperature (G42) | — | W41 | — | 0.5 | T2I-C1-32 | — | — | — |
| 86 | Camshaft position sensor (G40) | — | W24 | — | 0.5 | T2I-C1-12 | — | — | — |
| 88 | Injector 4 (N33) | — | — | — | — | — | — | — | — |
| 89 | Injector 2 (N31) | — | — | — | — | — | — | — | — |
| 9 | Secondary-air injection valve (N112) | — | — | — | — | — | — | — | — |
| 90 | Crank position sensor ground (G28) | — | W13 | — | 0.5 | SP-0V-1 | — | — | — |
| 91 | Throttle position sensor ground (G187/G188) | — | W14 | — | 0.5 | SP-0V-1 | — | — | — |
| 92 | Throttle position sensor 2 (G188) | — | W32 | — | 0.5 | T2I-C1-34 | — | — | — |
| 93 | Engine coolant temperature (G62) | — | W33 | — | 0.5 | T2I-C1-24 | — | — | — |
| 94 | Ignition coil 4 (N163) | — | — | — | — | — | — | — | — |
| 95 | Ignition coil 2 (N128) | — | W26 | — | 0.5 | T2I-C1-6 | — | — | — |
| 96 | Injector 1 (N30) | — | — | — | — | — | — | — | — |
| 97 | Injector 3 (N32) | — | — | — | — | — | — | — | — |
| 98 | Cam + boost sensor 5V supply (G40/G31) | — | W20 | — | 0.5 | SP-5V1-1 | — | — | — |
| 99 | Knock sensor 5V supply (G61/G66) | — | W21 | — | 0.5 | SP-5V1-1 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W9 | — | 0.5 | OEM-T121-108 | — | — | — |
| 1 | — | — | W10 | — | 0.5 | OEM-T121-29 | — | — | — |
| 1 | — | — | W11 | — | 0.5 | OEM-T121-34 | — | — | — |
| 1 | — | — | W12 | — | 0.5 | OEM-T121-36 | — | — | — |
| 1 | — | — | W13 | — | 0.5 | OEM-T121-90 | — | — | — |
| 1 | — | — | W14 | — | 0.5 | OEM-T121-91 | — | — | — |
| 1 | — | — | W15 | — | 0.5 | T2I-C1-28 | — | — | — |
| 1 | — | — | W16 | — | 0.5 | T2I-C1-29 | — | — | — |
SP-14V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W1 | — | 0.85 | OEM-T121-121 | — | — | — |
| 1 | — | — | W2 | — | 0.85 | OEM-T121-21 | — | — | — |
| 1 | — | — | W3 | — | 0.85 | T2I-C1-31 | — | — | — |
SP-5V1
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W17 | — | 0.5 | OEM-T121-72 | — | — | — |
| 1 | — | — | W18 | — | 0.5 | OEM-T121-73 | — | — | — |
| 1 | — | — | W19 | — | 0.5 | OEM-T121-83 | — | — | — |
| 1 | — | — | W20 | — | 0.5 | OEM-T121-98 | — | — | — |
| 1 | — | — | W21 | — | 0.5 | OEM-T121-99 | — | — | — |
| 1 | — | — | W22 | — | 0.5 | T2I-C1-27 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W5 | — | 0.85 | OEM-T121-1 | — | — | — |
| 1 | — | — | W6 | — | 0.85 | OEM-T121-2 | — | — | — |
| 1 | — | — | W7 | — | 0.85 | T2I-C1-13 | — | — | — |
| 1 | — | — | W8 | — | 0.85 | T2I-C1-14 | — | — | — |
T2I-C1
Mating face
Wire side
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | PWM 1 | — | W34 | — | 0.5 | OEM-T121-65 | — | — | — |
| 2 | Lambda Nernst Voltage | — | W40 | — | 0.5 | OEM-T121-70 | — | — | — |
| 3 | Coil 1 | — | W25 | — | 0.5 | OEM-T121-102 | — | — | — |
| 4 | Lambda VGND | — | — | — | — | — | — | — | — |
| 5 | Lambda Pump Current | — | W39 | — | 0.5 | OEM-T121-51 | — | — | — |
| 6 | Coil 2 | — | W26 | — | 0.5 | OEM-T121-95 | — | — | — |
| 7 | Lambda Trim Resistor | — | — | — | — | — | — | — | — |
| 8 | — | — | — | — | — | — | — | — | — |
| 9 | — | — | — | — | — | — | — | — | — |
| 10 | PWM 2 | — | W35 | — | 0.5 | OEM-T121-66 | — | — | — |
| 11 | Digital 1 | — | W42 | — | 0.5 | OEM-T121-54 | — | — | — |
| 12 | Wheel 1 | — | W24 | — | 0.5 | OEM-T121-86 | — | — | — |
| 13 | Power Ground 1 | — | W7 | — | 0.85 | SP-GND-1 | — | — | — |
| 14 | Power Ground 2 | — | W8 | — | 0.85 | SP-GND-1 | — | — | — |
| 15 | Lambda Heater Negative | — | W36 | — | 0.5 | OEM-T121-5 | — | — | — |
| 16 | CAN High | — | W43 | — | 0.5 | OEM-T121-60 | — | — | — |
| 17 | CAN Low | — | W44 | — | 0.5 | OEM-T121-58 | — | — | — |
| 18 | PWM 3 | — | W37 | — | 0.5 | OEM-T121-63 | — | — | — |
| 19 | Crank | — | W23 | — | 0.5 | OEM-T121-82 | — | — | — |
| 20 | Analogue 1 | — | W27 | — | 0.5 | OEM-T121-53 | — | — | — |
| 21 | Permanent 12v | — | W4 | — | 0.85 | OEM-T121-62 | — | — | — |
| 22 | Analogue 2 | — | W28 | — | 0.5 | OEM-T121-101 | — | — | — |
| 23 | Analogue 3 | — | W29 | — | 0.5 | OEM-T121-33 | — | — | — |
| 24 | Thermistor 1 | — | W33 | — | 0.5 | OEM-T121-93 | — | — | — |
| 25 | Analogue 4 | — | W30 | — | 0.5 | OEM-T121-84 | — | — | — |
| 26 | PWM 4 | — | W38 | — | 0.5 | OEM-T121-104 | — | — | — |
| 27 | 5v Output | — | W22 | — | 0.5 | SP-5V1-1 | — | — | — |
| 28 | Sensor Ground | — | W15 | — | 0.5 | SP-0V-1 | — | — | — |
| 29 | Sensor Ground | — | W16 | — | 0.5 | SP-0V-1 | — | — | — |
| 30 | Digital 2 | — | — | — | — | — | — | — | — |
| 31 | Ignition 12v In | — | W3 | — | 0.85 | SP-14V-1 | — | — | — |
| 32 | Thermistor 2 | — | W41 | — | 0.5 | OEM-T121-85 | — | — | — |
| 33 | Analogue 5 | — | W31 | — | 0.5 | OEM-T121-35 | — | — | — |
| 34 | Analogue 6 | — | W32 | — | 0.5 | OEM-T121-92 | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| OEM-T121-1 | ECU ground | ground | T2I-C1-13 + T2I-C1-14 | Power Ground 1 + Power Ground 2 | ground | corroborated | |
| OEM-T121-101 | Boost pressure sensor (G31) | analog_in | T2I-C1-22 | Analogue 2 | analog_in | corroborated | |
| OEM-T121-102 | Ignition coil 1 (N127) | ignition_out | T2I-C1-3 | Coil 1 | ignition_out | corroborated | |
| OEM-T121-103 | Ignition coil 3 (N158) | ignition_out | — | — | — | corroborated | |
| OEM-T121-104 | Boost control solenoid (N75) | low_side_out | T2I-C1-26 | PWM 4 | low_side_out | corroborated | |
| OEM-T121-105 | Diverter valve (N249) | low_side_out | — | — | — | corroborated | |
| OEM-T121-106 | Knock sensor 1 (G61) | knock_in | — | — | — | corroborated | |
| OEM-T121-107 | Knock sensor 2 (G66) | knock_in | — | — | — | corroborated | |
| OEM-T121-108 | Sensor ground | sensor_ground | T2I-C1-28 + T2I-C1-29 | Sensor Ground + Sensor Ground | sensor_ground | corroborated | |
| OEM-T121-115 | VVT camshaft adjustment valve (N205) | low_side_out | — | — | — | corroborated | |
| OEM-T121-117 | Throttle motor G186 (+) | hbridge_out | — | — | — | corroborated | |
| OEM-T121-118 | Throttle motor G186 (−) | hbridge_out | — | — | — | corroborated | |
| OEM-T121-121 | ECM + coil power (J271 relay feed) | power_in | T2I-C1-31 | Ignition 12v In | power_in | corroborated | |
| OEM-T121-2 | ECU ground | ground | T2I-C1-13 + T2I-C1-14 | Power Ground 1 + Power Ground 2 | ground | corroborated | |
| OEM-T121-21 | ECM power (J271 relay feed) | power_in | T2I-C1-31 | Ignition 12v In | power_in | corroborated | |
| OEM-T121-27 | MAF sensor supply (G70) | power_in | — | — | — | corroborated | |
| OEM-T121-29 | MAF sensor ground (G70) | sensor_ground | T2I-C1-28 + T2I-C1-29 | Sensor Ground + Sensor Ground | sensor_ground | corroborated | |
| OEM-T121-3 | Ignition switch +12V (term 15) | digital_in | — | — | — | corroborated | |
| OEM-T121-33 | Accelerator pedal position 1 (G79) | analog_in | T2I-C1-23 | Analogue 3 | analog_in | corroborated | |
| OEM-T121-34 | Accelerator pedal position 1 ground (G79) | sensor_ground | T2I-C1-28 + T2I-C1-29 | Sensor Ground + Sensor Ground | sensor_ground | corroborated | |
| OEM-T121-35 | Accelerator pedal position 2 (G185) | analog_in | T2I-C1-33 | Analogue 5 | analog_in | corroborated | |
| OEM-T121-36 | Accelerator pedal position 2 ground (G185) | sensor_ground | T2I-C1-28 + T2I-C1-29 | Sensor Ground + Sensor Ground | sensor_ground | corroborated | |
| OEM-T121-37 | Engine speed signal (tacho to cluster) | tacho_out | — | — | — | corroborated | |
| OEM-T121-43 | K-line diagnostics (OBD pin 7) | serial | — | — | — | corroborated | |
| OEM-T121-47 | Check engine light (MIL) | low_side_out | — | — | — | corroborated | |
| OEM-T121-48 | EPC warning light | low_side_out | — | — | — | corroborated | |
| OEM-T121-5 | Wideband lambda heater (Z19) | low_side_out | T2I-C1-15 | Lambda Heater Negative | low_side_out | corroborated | |
| OEM-T121-51 | Wideband lambda pump (G39) | wb_ip | T2I-C1-5 | Lambda Pump Current | wb_ip | corroborated | |
| OEM-T121-52 | Wideband lambda pump (G39) | wb_ip | — | — | — | corroborated | |
| OEM-T121-53 | MAF sensor signal (G70) | analog_in | T2I-C1-20 | Analogue 1 | analog_in | corroborated | |
| OEM-T121-54 | Road speed signal (VSS) | digital_in | T2I-C1-11 | Digital 1 | digital_in | corroborated | |
| OEM-T121-58 | CAN bus low | can_l | T2I-C1-17 | CAN Low | can_l | corroborated | |
| OEM-T121-60 | CAN bus high | can_h | T2I-C1-16 | CAN High | can_h | corroborated | |
| OEM-T121-62 | Battery constant +12V (term 30) | power_in | T2I-C1-21 | Permanent 12v | power_in | corroborated | |
| OEM-T121-63 | Post-cat lambda heater (Z29) | low_side_out | T2I-C1-18 | PWM 3 | low_side_out | corroborated | |
| OEM-T121-64 | EVAP canister valve (N80) | low_side_out | — | — | — | corroborated | |
| OEM-T121-65 | Fuel pump relay control | low_side_out | T2I-C1-1 | PWM 1 | low_side_out | corroborated | |
| OEM-T121-66 | Secondary-air pump relay (J299) | low_side_out | T2I-C1-10 | PWM 2 | low_side_out | corroborated | |
| OEM-T121-68 | Post-cat lambda signal (G130) | lambda_nb_in | — | — | — | corroborated | |
| OEM-T121-69 | Post-cat lambda signal (G130) | lambda_nb_in | — | — | — | corroborated | |
| OEM-T121-70 | Wideband lambda Nernst signal (G39) | wb_vs | T2I-C1-2 | Lambda Nernst Voltage | wb_vs | corroborated | |
| OEM-T121-71 | Wideband lambda Nernst signal (G39) | wb_vs | — | — | — | corroborated | |
| OEM-T121-72 | Accelerator pedal position 1 5V supply (G79) | vref | T2I-C1-27 | 5v Output | vref | corroborated | |
| OEM-T121-73 | Accelerator pedal position 2 5V supply (G185) | vref | T2I-C1-27 | 5v Output | vref | corroborated | |
| OEM-T121-82 | Crank position sensor (G28) | trigger_in | T2I-C1-19 | Crank | trigger_in | corroborated | |
| OEM-T121-83 | Throttle position sensor 5V supply (G187/G188) | vref | T2I-C1-27 | 5v Output | vref | corroborated | |
| OEM-T121-84 | Throttle position sensor 1 (G187) | analog_in | T2I-C1-25 | Analogue 4 | analog_in | corroborated | |
| OEM-T121-85 | Intake air temperature (G42) | temp_in | T2I-C1-32 | Thermistor 2 | temp_in | corroborated | |
| OEM-T121-86 | Camshaft position sensor (G40) | trigger_in | T2I-C1-12 | Wheel 1 | digital_in | corroborated | |
| OEM-T121-88 | Injector 4 (N33) | injector_out | — | — | — | corroborated | |
| OEM-T121-89 | Injector 2 (N31) | injector_out | — | — | — | corroborated | |
| OEM-T121-9 | Secondary-air injection valve (N112) | low_side_out | — | — | — | corroborated | |
| OEM-T121-90 | Crank position sensor ground (G28) | sensor_ground | T2I-C1-28 + T2I-C1-29 | Sensor Ground + Sensor Ground | sensor_ground | corroborated | |
| OEM-T121-91 | Throttle position sensor ground (G187/G188) | sensor_ground | T2I-C1-28 + T2I-C1-29 | Sensor Ground + Sensor Ground | sensor_ground | corroborated | |
| OEM-T121-92 | Throttle position sensor 2 (G188) | analog_in | T2I-C1-34 | Analogue 6 | analog_in | corroborated | |
| OEM-T121-93 | Engine coolant temperature (G62) | temp_in | T2I-C1-24 | Thermistor 1 | temp_in | corroborated | |
| OEM-T121-94 | Ignition coil 4 (N163) | ignition_out | — | — | — | corroborated | |
| OEM-T121-95 | Ignition coil 2 (N128) | ignition_out | T2I-C1-6 | Coil 2 | ignition_out | corroborated | |
| OEM-T121-96 | Injector 1 (N30) | injector_out | — | — | — | corroborated | |
| OEM-T121-97 | Injector 3 (N32) | injector_out | — | — | — | corroborated | |
| OEM-T121-98 | Cam + boost sensor 5V supply (G40/G31) | vref | T2I-C1-27 | 5v Output | vref | corroborated | |
| OEM-T121-99 | Knock sensor 5V supply (G61/G66) | vref | T2I-C1-27 | 5v Output | vref | corroborated |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-T121-121 | SP-14V-1 | 0.85 | no route | ECM + coil power (J271 relay feed) | — | |
| W2 | OEM-T121-21 | SP-14V-1 | 0.85 | no route | ECM power (J271 relay feed) | — | |
| W3 | SP-14V-1 | T2I-C1-31 | 0.85 | no route | Ignition 12v In | — | |
| W4 | OEM-T121-62 | T2I-C1-21 | 0.85 | no route | Battery constant +12V (term 30) | — | |
| W5 | OEM-T121-1 | SP-GND-1 | 0.85 | no route | ECU ground | — | |
| W6 | OEM-T121-2 | SP-GND-1 | 0.85 | no route | ECU ground | — | |
| W7 | SP-GND-1 | T2I-C1-13 | 0.85 | no route | Power Ground 1 | — | |
| W8 | SP-GND-1 | T2I-C1-14 | 0.85 | no route | Power Ground 2 | — | |
| W9 | OEM-T121-108 | SP-0V-1 | 0.5 | no route | Sensor ground | — | |
| W10 | OEM-T121-29 | SP-0V-1 | 0.5 | no route | MAF sensor ground (G70) | — | |
| W11 | OEM-T121-34 | SP-0V-1 | 0.5 | no route | Accelerator pedal position 1 ground (G79) | — | |
| W12 | OEM-T121-36 | SP-0V-1 | 0.5 | no route | Accelerator pedal position 2 ground (G185) | — | |
| W13 | OEM-T121-90 | SP-0V-1 | 0.5 | no route | Crank position sensor ground (G28) | — | |
| W14 | OEM-T121-91 | SP-0V-1 | 0.5 | no route | Throttle position sensor ground (G187/G188) | — | |
| W15 | SP-0V-1 | T2I-C1-28 | 0.5 | no route | Sensor Ground | — | |
| W16 | SP-0V-1 | T2I-C1-29 | 0.5 | no route | Sensor Ground | — | |
| W17 | OEM-T121-72 | SP-5V1-1 | 0.5 | no route | Accelerator pedal position 1 5V supply (G79) | — | |
| W18 | OEM-T121-73 | SP-5V1-1 | 0.5 | no route | Accelerator pedal position 2 5V supply (G185) | — | |
| W19 | OEM-T121-83 | SP-5V1-1 | 0.5 | no route | Throttle position sensor 5V supply (G187/G188) | — | |
| W20 | OEM-T121-98 | SP-5V1-1 | 0.5 | no route | Cam + boost sensor 5V supply (G40/G31) | — | |
| W21 | OEM-T121-99 | SP-5V1-1 | 0.5 | no route | Knock sensor 5V supply (G61/G66) | — | |
| W22 | SP-5V1-1 | T2I-C1-27 | 0.5 | no route | 5v Output | — | |
| W23 | OEM-T121-82 | T2I-C1-19 | 0.5 | no route | Crank position sensor (G28) | — | |
| W24 | OEM-T121-86 | T2I-C1-12 | 0.5 | no route | Camshaft position sensor (G40) | — | |
| W25 | OEM-T121-102 | T2I-C1-3 | 0.5 | no route | Ignition coil 1 (N127) | — | |
| W26 | OEM-T121-95 | T2I-C1-6 | 0.5 | no route | Ignition coil 2 (N128) | — | |
| W27 | OEM-T121-53 | T2I-C1-20 | 0.5 | no route | MAF sensor signal (G70) | — | |
| W28 | OEM-T121-101 | T2I-C1-22 | 0.5 | no route | Boost pressure sensor (G31) | — | |
| W29 | OEM-T121-33 | T2I-C1-23 | 0.5 | no route | Accelerator pedal position 1 (G79) | — | |
| W30 | OEM-T121-84 | T2I-C1-25 | 0.5 | no route | Throttle position sensor 1 (G187) | — | |
| W31 | OEM-T121-35 | T2I-C1-33 | 0.5 | no route | Accelerator pedal position 2 (G185) | — | |
| W32 | OEM-T121-92 | T2I-C1-34 | 0.5 | no route | Throttle position sensor 2 (G188) | — | |
| W33 | OEM-T121-93 | T2I-C1-24 | 0.5 | no route | Engine coolant temperature (G62) | — | |
| W34 | OEM-T121-65 | T2I-C1-1 | 0.5 | no route | Fuel pump relay control | — | |
| W35 | OEM-T121-66 | T2I-C1-10 | 0.5 | no route | Secondary-air pump relay (J299) | — | |
| W36 | OEM-T121-5 | T2I-C1-15 | 0.5 | no route | Wideband lambda heater (Z19) | — | |
| W37 | OEM-T121-63 | T2I-C1-18 | 0.5 | no route | Post-cat lambda heater (Z29) | — | |
| W38 | OEM-T121-104 | T2I-C1-26 | 0.5 | no route | Boost control solenoid (N75) | — | |
| W39 | OEM-T121-51 | T2I-C1-5 | 0.5 | no route | Wideband lambda pump (G39) | — | |
| W40 | OEM-T121-70 | T2I-C1-2 | 0.5 | no route | Wideband lambda Nernst signal (G39) | — | |
| W41 | OEM-T121-85 | T2I-C1-32 | 0.5 | no route | Intake air temperature (G42) | — | |
| W42 | OEM-T121-54 | T2I-C1-11 | 0.5 | no route | Road speed signal (VSS) | — | |
| W43 | OEM-T121-60 | T2I-C1-16 | 0.5 | no route | CAN bus high | — | |
| W44 | OEM-T121-58 | T2I-C1-17 | 0.5 | no route | CAN bus low | — |
Bill of materials
| Category | Part number | Manufacturer | Description | Qty | Unit |
|---|---|---|---|---|---|
| connector | 4-1437290-0 | TE | Superseal 1.0 34-way plug, Key 1 | 1.000 | ea |
| terminal | 3-1447221-4 | TE | Superseal 1.0 socket terminal, 20 AWG (0.5 sq mm) | 29.000 | ea |
ECU setup sheet
| Role | Engine ref | Engine signal | Sensor | ECU point | ECU function | ECU class | Setup flag |
|---|---|---|---|---|---|---|---|
| No configured channels. | |||||||
Findings
Open (16)
| Severity | Code | Subject | Message |
|---|---|---|---|
| error | REQUIRED_UNMAPPED | OEM-T121-103 | Required OEM function "Ignition coil 3 (N158)" (ignition_out) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-T121-106 | Required OEM function "Knock sensor 1 (G61)" (knock_in) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-T121-107 | Required OEM function "Knock sensor 2 (G66)" (knock_in) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-T121-117 | Required OEM function "Throttle motor G186 (+)" (hbridge_out) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-T121-118 | Required OEM function "Throttle motor G186 (−)" (hbridge_out) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-T121-3 | Required OEM function "Ignition switch +12V (term 15)" (digital_in) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-T121-88 | Required OEM function "Injector 4 (N33)" (injector_out) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-T121-89 | Required OEM function "Injector 2 (N31)" (injector_out) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-T121-94 | Required OEM function "Ignition coil 4 (N163)" (ignition_out) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-T121-96 | Required OEM function "Injector 1 (N30)" (injector_out) is not connected to the new ECU. |
| error | REQUIRED_UNMAPPED | OEM-T121-97 | Required OEM function "Injector 3 (N32)" (injector_out) is not connected to the new ECU. |
| warn | DATASET_GAP | T2i C1 | 2 of 34 cavities on T2i C1 have no pin data (8,9). Anything there is invisible to these checks. |
| warn | DBW_SHARED_5V | OEM-T121-72 + OEM-T121-73 + OEM-T121-83 + OEM-T121-98 + OEM-T121-99 + SP-5V1-1 + T2I-C1-27 | These 5 V supplies are separate in the stock car (OEM-T121-72 [pedal1], OEM-T121-73 [pedal2], OEM-T121-83 [tps], OEM-T121-98 [cam_boost], OEM-T121-99 [knock]) and here share one ECU 5 V (T2I-C1-27). On a drive-by-wire car the OEM splits them so one short or fault can't corrupt both throttle/pedal tracks at once. T2i has 1 5 V sensor supply pin(s). All are in use, so decide: accept the shared supply (and rely on the ECU's DBW fault checks), or add a separate regulated 5 V for the sub tracks. |
| warn | NET_FAMILY | OEM-T121-86 ↔ T2I-C1-12 | OEM-T121-86 "Camshaft position sensor (G40)" [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. |
| warn | SUPPLY_GROUP | OEM-T121-72 + OEM-T121-73 + OEM-T121-83 + OEM-T121-98 + OEM-T121-99 + SP-5V1-1 + T2I-C1-27 | Supplies meant to stay independent share one net: OEM-T121-72 [pedal1], OEM-T121-73 [pedal2], OEM-T121-83 [tps], OEM-T121-98 [cam_boost], OEM-T121-99 [knock]. The new ECU has no free 5 V reference, so they share one: normal on a standalone, but a short on any of these sensors drops them all. |
| info | UNMAPPED | OEM | 13 optional OEM pins are not mapped: OEM-T121-105 Diverter valve (N249); OEM-T121-115 VVT camshaft adjustment valve (N205); OEM-T121-27 MAF sensor supply (G70); OEM-T121-37 Engine speed signal (tacho to cluster); OEM-T121-43 K-line diagnostics (OBD pin 7); OEM-T121-47 Check engine light (MIL); OEM-T121-48 EPC warning light; OEM-T121-52 Wideband lambda pump (G39); OEM-T121-64 EVAP canister valve (N80); OEM-T121-68 Post-cat lambda signal (G130); OEM-T121-69 Post-cat lambda signal (G130); OEM-T121-71 Wideband lambda Nernst signal (G39); OEM-T121-9 Secondary-air injection valve (N112) |
Accepted (0)
| Code | Subject | Reason | By |
|---|
Notes
Fit check: needs add-on. Resolve these before building: - No drive-by-wire; needs a cable-throttle conversion or an external DBW controller - No knock input; the stock knock sensor would be unused - Only 2 ignition outputs for 4 cylinders: wasted spark (pair coils per firing order) - This car has VW/Audi Immobilizer (delete/bypass for standalone) immobilizer; needs a delete/bypass Auto-mapped by auto_map() from the library pin data on 2026-10-11. Review every wire against both manuals before building. Open items: - OEM-T121 106: Knock sensor 1 (G61): no free knock input on DTAFast T2i - OEM-T121 107: Knock sensor 2 (G66): no free knock input on DTAFast T2i - OEM-T121 103: Ignition coil 3 (N158): no free ignition output on DTAFast T2i - OEM-T121 94: Ignition coil 4 (N163): no free ignition output on DTAFast T2i - OEM-T121 96: Injector 1 (N30): no free injector output on DTAFast T2i - OEM-T121 89: Injector 2 (N31): no free injector output on DTAFast T2i - OEM-T121 97: Injector 3 (N32): no free injector output on DTAFast T2i - OEM-T121 88: Injector 4 (N33): no free injector output on DTAFast T2i - OEM-T121 117: Throttle motor G186 (+): needs a paired H-bridge on DTAFast T2i (H-bridge pairing not in the library: set device_pin.bridge_pair from the ECU manual) - OEM-T121 118: Throttle motor G186 (−): needs a paired H-bridge on DTAFast T2i (H-bridge pairing not in the library: set device_pin.bridge_pair from the ECU manual) - OEM-T121 3: Ignition switch +12V (term 15): key-on 12 V sense — optional in a swap (the main relay is energized from keyed 12 V, not from this pin); DTAFast T2i has no dedicated key-on input Not wired: - OEM-T121 105: Diverter valve (N249): no free low_side/relay_control/heater_low_side/ls_hs/injector on DTAFast T2i - OEM-T121 115: VVT camshaft adjustment valve (N205): no free low_side/relay_control/heater_low_side/ls_hs/injector on DTAFast T2i - OEM-T121 47: Check engine light (MIL): no free low_side/relay_control/heater_low_side/ls_hs/injector on DTAFast T2i - OEM-T121 48: EPC warning light: no free low_side/relay_control/heater_low_side/ls_hs/injector on DTAFast T2i - OEM-T121 64: EVAP canister valve (N80): no free low_side/relay_control/heater_low_side/ls_hs/injector on DTAFast T2i - OEM-T121 9: Secondary-air injection valve (N112): no free low_side/relay_control/heater_low_side/ls_hs/injector on DTAFast T2i - OEM-T121 37: Engine speed signal (tacho to cluster): no free tacho/frequency_out/low_side/ls_hs on DTAFast T2i - OEM-T121 52: Wideband lambda pump (G39): no free wb_ip on DTAFast T2i - OEM-T121 71: Wideband lambda Nernst signal (G39): no free wb_vs on DTAFast T2i - OEM-T121 68: Post-cat lambda signal (G130): no free o2_narrowband/analog_0_5 on DTAFast T2i - OEM-T121 69: Post-cat lambda signal (G130): no free o2_narrowband/analog_0_5 on DTAFast T2i - OEM-T121 43: K-line diagnostics (OBD pin 7): no free k_line on DTAFast T2i - OEM-T121 27: MAF sensor supply (G70): no rule for class sensor_supply_in; wire by hand
Sources
| Reliability | Kind | Title | URL | Archive | Captured | SHA-256 |
|---|---|---|---|---|---|---|
| 4 | vendor_doc | DTAFast T2i ECU wiring diagram | https://cdn.shopify.com/s/files/1/0848/7508/4108/files/T2i_Wiring-Diagram.pdf?v=1728571341 | — | — | — |
| 3 | community_copy | NefMoto: ME7.5 ECU bench-flashing power/ground pins | http://nefmoto.com/wiki/index.php?title=ECU_Bench_Flashing | — | — | — |
| 3 | community_copy | vwressources: Bosch Motronic ME7.5 (AMK/ARY/AUQ/ARX/AUM) T121 pinout | https://www.vwressources.planethoster.world/me75_pinout.html | — | — | — |