VW Golf Mk4 1.8T 20v (AUM, Bosch ME7.5) DBW → FuelTech FT450 (auto)
VW Golf Mk4 1.8T 20v (AUM, Bosch ME7.5) DBW — FuelTech — FT450
⚠ 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 | 8: read the Findings page before cutting any wire |
| Size of the job | 43 wires · 6 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-T121-121 | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | OEM-T121-21 | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | SP-14V-1 | FT450-A-A13 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | OEM-T121-1 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | OEM-T121-2 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | SP-GND-1 | FT450-A-A7 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | OEM-T121-108 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | OEM-T121-29 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | OEM-T121-34 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | OEM-T121-36 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | OEM-T121-90 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | OEM-T121-91 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | SP-0V-1 | FT450-A-A12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-T121-72 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | OEM-T121-73 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | OEM-T121-83 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-T121-98 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-T121-99 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | SP-5V1-1 | FT450-A-A14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-T121-82 | FT450-A-A18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | SP-0V-1 | FT450-A-A18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-T121-86 | FT450-A-A17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-T121-102 | FT450-A-A8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-T121-95 | FT450-A-A9 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-T121-103 | FT450-A-A10 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-T121-94 | FT450-A-A11 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-T121-96 | FT450-A-A1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-T121-89 | FT450-A-A2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-T121-97 | FT450-A-A1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-T121-88 | FT450-A-A2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W31 | OEM-T121-53 | FT450-A-A20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W32 | OEM-T121-101 | FT450-A-A23 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W33 | OEM-T121-33 | FT450-A-A21 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W34 | OEM-T121-84 | FT450-A-A22 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W35 | OEM-T121-35 | FT450-A-A25 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W36 | OEM-T121-93 | FT450-A-A24 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W37 | OEM-T121-65 | FT450-A-A6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W38 | OEM-T121-66 | FT450-A-A3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W39 | OEM-T121-5 | FT450-A-A4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W40 | OEM-T121-63 | FT450-A-A5 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W41 | OEM-T121-85 | FT450-A-A26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W42 | OEM-T121-60 | FT450-A-A16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W43 | OEM-T121-58 | FT450-A-A15 | 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 | FT450-A-A12 | FT450-A-A13 | open (OL) | sensor ground must not touch +12 V supply | |
| 2 | FT450-A-A12 | FT450-A-A14 | open (OL) | sensor ground must not touch 5 V sensor reference | |
| 3 | FT450-A-A13 | FT450-A-A14 | open (OL) | +12 V supply must not touch 5 V sensor reference | |
| 4 | FT450-A-A7 | FT450-A-A13 | open (OL) | power ground must not touch +12 V supply | |
| 5 | FT450-A-A7 | FT450-A-A14 | open (OL) | power ground 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
FT450-A
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A1 | Injector 1 (Bank A) | — | W27 | — | 0.5 | OEM-T121-96 | — | — | — |
| A1 | Injector 1 (Bank A) | — | W29 | — | 0.5 | OEM-T121-97 | — | — | — |
| A10 | Ignition 3 | — | W25 | — | 0.5 | OEM-T121-103 | — | — | — |
| A11 | Ignition 4 | — | W26 | — | 0.5 | OEM-T121-94 | — | — | — |
| A12 | Signal ground | — | W13 | — | 0.5 | SP-0V-1 | — | — | — |
| A13 | +12V switched | — | W3 | — | 0.85 | SP-14V-1 | — | — | — |
| A14 | +5V sensor supply | — | W19 | — | 0.5 | SP-5V1-1 | — | — | — |
| A15 | CAN A LOW | — | W43 | — | 0.5 | OEM-T121-58 | — | — | — |
| A16 | CAN A HIGH | — | W42 | — | 0.5 | OEM-T121-60 | — | — | — |
| A17 | Phase input (cam) | — | W22 | — | 0.5 | OEM-T121-86 | — | — | — |
| A18 | RPM reference (crank -) | — | W20 | — | 0.5 | OEM-T121-82 | — | — | — |
| A18 | RPM reference (crank -) | — | W21 | — | 0.5 | SP-0V-1 | — | — | — |
| A19 | RPM signal (crank +) | — | — | — | — | — | — | — | — |
| A2 | Injector 2 (Bank A) | — | W28 | — | 0.5 | OEM-T121-89 | — | — | — |
| A2 | Injector 2 (Bank A) | — | W30 | — | 0.5 | OEM-T121-88 | — | — | — |
| A20 | White input 1 | — | W31 | — | 0.5 | OEM-T121-53 | — | — | — |
| A21 | White input 2 | — | W33 | — | 0.5 | OEM-T121-33 | — | — | — |
| A22 | White input 3 (TPS) | — | W34 | — | 0.5 | OEM-T121-84 | — | — | — |
| A23 | White input 4 (oil pressure) | — | W32 | — | 0.5 | OEM-T121-101 | — | — | — |
| A24 | White input 5 (water temp) | — | W36 | — | 0.5 | OEM-T121-93 | — | — | — |
| A25 | White input 6 (fuel pressure) | — | W35 | — | 0.5 | OEM-T121-35 | — | — | — |
| A26 | White input 7 (air temp) | — | W41 | — | 0.5 | OEM-T121-85 | — | — | — |
| A3 | Aux 1 | — | W38 | — | 0.5 | OEM-T121-66 | — | — | — |
| A4 | Aux 2 | — | W39 | — | 0.5 | OEM-T121-5 | — | — | — |
| A5 | Aux 3 | — | W40 | — | 0.5 | OEM-T121-63 | — | — | — |
| A6 | Aux 4 (fuel pump / relays) | — | W37 | — | 0.5 | OEM-T121-65 | — | — | — |
| A7 | Power ground | — | W6 | — | 0.85 | SP-GND-1 | — | — | — |
| A8 | Ignition 1 | — | W23 | — | 0.5 | OEM-T121-102 | — | — | — |
| A9 | Ignition 2 | — | W24 | — | 0.5 | OEM-T121-95 | — | — | — |
OEM-T121
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | ECU ground | — | W4 | — | 0.85 | SP-GND-1 | — | — | — |
| 101 | Boost pressure sensor (G31) | — | W32 | — | 0.5 | FT450-A-A23 | — | — | — |
| 102 | Ignition coil 1 (N127) | — | W23 | — | 0.5 | FT450-A-A8 | — | — | — |
| 103 | Ignition coil 3 (N158) | — | W25 | — | 0.5 | FT450-A-A10 | — | — | — |
| 104 | Boost control solenoid (N75) | — | — | — | — | — | — | — | — |
| 105 | Diverter valve (N249) | — | — | — | — | — | — | — | — |
| 106 | Knock sensor 1 (G61) | — | — | — | — | — | — | — | — |
| 107 | Knock sensor 2 (G66) | — | — | — | — | — | — | — | — |
| 108 | Sensor ground | — | W7 | — | 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 | — | W5 | — | 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) | — | W8 | — | 0.5 | SP-0V-1 | — | — | — |
| 3 | Ignition switch +12V (term 15) | — | — | — | — | — | — | — | — |
| 33 | Accelerator pedal position 1 (G79) | — | W33 | — | 0.5 | FT450-A-A21 | — | — | — |
| 34 | Accelerator pedal position 1 ground (G79) | — | W9 | — | 0.5 | SP-0V-1 | — | — | — |
| 35 | Accelerator pedal position 2 (G185) | — | W35 | — | 0.5 | FT450-A-A25 | — | — | — |
| 36 | Accelerator pedal position 2 ground (G185) | — | W10 | — | 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) | — | W39 | — | 0.5 | FT450-A-A4 | — | — | — |
| 51 | Wideband lambda pump (G39) | — | — | — | — | — | — | — | — |
| 52 | Wideband lambda pump (G39) | — | — | — | — | — | — | — | — |
| 53 | MAF sensor signal (G70) | — | W31 | — | 0.5 | FT450-A-A20 | — | — | — |
| 54 | Road speed signal (VSS) | — | — | — | — | — | — | — | — |
| 58 | CAN bus low | — | W43 | — | 0.5 | FT450-A-A15 | — | — | — |
| 60 | CAN bus high | — | W42 | — | 0.5 | FT450-A-A16 | — | — | — |
| 62 | Battery constant +12V (term 30) | — | — | — | — | — | — | — | — |
| 63 | Post-cat lambda heater (Z29) | — | W40 | — | 0.5 | FT450-A-A5 | — | — | — |
| 64 | EVAP canister valve (N80) | — | — | — | — | — | — | — | — |
| 65 | Fuel pump relay control | — | W37 | — | 0.5 | FT450-A-A6 | — | — | — |
| 66 | Secondary-air pump relay (J299) | — | W38 | — | 0.5 | FT450-A-A3 | — | — | — |
| 68 | Post-cat lambda signal (G130) | — | — | — | — | — | — | — | — |
| 69 | Post-cat lambda signal (G130) | — | — | — | — | — | — | — | — |
| 70 | Wideband lambda Nernst signal (G39) | — | — | — | — | — | — | — | — |
| 71 | Wideband lambda Nernst signal (G39) | — | — | — | — | — | — | — | — |
| 72 | Accelerator pedal position 1 5V supply (G79) | — | W14 | — | 0.5 | SP-5V1-1 | — | — | — |
| 73 | Accelerator pedal position 2 5V supply (G185) | — | W15 | — | 0.5 | SP-5V1-1 | — | — | — |
| 82 | Crank position sensor (G28) | — | W20 | — | 0.5 | FT450-A-A18 | — | — | — |
| 83 | Throttle position sensor 5V supply (G187/G188) | — | W16 | — | 0.5 | SP-5V1-1 | — | — | — |
| 84 | Throttle position sensor 1 (G187) | — | W34 | — | 0.5 | FT450-A-A22 | — | — | — |
| 85 | Intake air temperature (G42) | — | W41 | — | 0.5 | FT450-A-A26 | — | — | — |
| 86 | Camshaft position sensor (G40) | — | W22 | — | 0.5 | FT450-A-A17 | — | — | — |
| 88 | Injector 4 (N33) | — | W30 | — | 0.5 | FT450-A-A2 | — | — | — |
| 89 | Injector 2 (N31) | — | W28 | — | 0.5 | FT450-A-A2 | — | — | — |
| 9 | Secondary-air injection valve (N112) | — | — | — | — | — | — | — | — |
| 90 | Crank position sensor ground (G28) | — | W11 | — | 0.5 | SP-0V-1 | — | — | — |
| 91 | Throttle position sensor ground (G187/G188) | — | W12 | — | 0.5 | SP-0V-1 | — | — | — |
| 92 | Throttle position sensor 2 (G188) | — | — | — | — | — | — | — | — |
| 93 | Engine coolant temperature (G62) | — | W36 | — | 0.5 | FT450-A-A24 | — | — | — |
| 94 | Ignition coil 4 (N163) | — | W26 | — | 0.5 | FT450-A-A11 | — | — | — |
| 95 | Ignition coil 2 (N128) | — | W24 | — | 0.5 | FT450-A-A9 | — | — | — |
| 96 | Injector 1 (N30) | — | W27 | — | 0.5 | FT450-A-A1 | — | — | — |
| 97 | Injector 3 (N32) | — | W29 | — | 0.5 | FT450-A-A1 | — | — | — |
| 98 | Cam + boost sensor 5V supply (G40/G31) | — | W17 | — | 0.5 | SP-5V1-1 | — | — | — |
| 99 | Knock sensor 5V supply (G61/G66) | — | W18 | — | 0.5 | SP-5V1-1 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W7 | — | 0.5 | OEM-T121-108 | — | — | — |
| 1 | — | — | W8 | — | 0.5 | OEM-T121-29 | — | — | — |
| 1 | — | — | W9 | — | 0.5 | OEM-T121-34 | — | — | — |
| 1 | — | — | W10 | — | 0.5 | OEM-T121-36 | — | — | — |
| 1 | — | — | W11 | — | 0.5 | OEM-T121-90 | — | — | — |
| 1 | — | — | W12 | — | 0.5 | OEM-T121-91 | — | — | — |
| 1 | — | — | W13 | — | 0.5 | FT450-A-A12 | — | — | — |
| 1 | — | — | W21 | — | 0.5 | FT450-A-A18 | — | — | — |
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 | FT450-A-A13 | — | — | — |
SP-5V1
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W14 | — | 0.5 | OEM-T121-72 | — | — | — |
| 1 | — | — | W15 | — | 0.5 | OEM-T121-73 | — | — | — |
| 1 | — | — | W16 | — | 0.5 | OEM-T121-83 | — | — | — |
| 1 | — | — | W17 | — | 0.5 | OEM-T121-98 | — | — | — |
| 1 | — | — | W18 | — | 0.5 | OEM-T121-99 | — | — | — |
| 1 | — | — | W19 | — | 0.5 | FT450-A-A14 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W4 | — | 0.85 | OEM-T121-1 | — | — | — |
| 1 | — | — | W5 | — | 0.85 | OEM-T121-2 | — | — | — |
| 1 | — | — | W6 | — | 0.85 | FT450-A-A7 | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| OEM-T121-1 | ECU ground | ground | FT450-A-A7 | Power ground | ground | corroborated | |
| OEM-T121-101 | Boost pressure sensor (G31) | analog_in | FT450-A-A23 | White input 4 (oil pressure) | analog_in | corroborated | |
| OEM-T121-102 | Ignition coil 1 (N127) | ignition_out | FT450-A-A8 | Ignition 1 | ignition_out | corroborated | |
| OEM-T121-103 | Ignition coil 3 (N158) | ignition_out | FT450-A-A10 | Ignition 3 | ignition_out | corroborated | |
| OEM-T121-104 | Boost control solenoid (N75) | 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 | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | 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 | FT450-A-A13 | +12V switched | power_in | corroborated | |
| OEM-T121-2 | ECU ground | ground | FT450-A-A7 | Power ground | ground | corroborated | |
| OEM-T121-21 | ECM power (J271 relay feed) | power_in | FT450-A-A13 | +12V switched | power_in | corroborated | |
| OEM-T121-27 | MAF sensor supply (G70) | power_in | — | — | — | corroborated | |
| OEM-T121-29 | MAF sensor ground (G70) | sensor_ground | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | corroborated | |
| OEM-T121-3 | Ignition switch +12V (term 15) | digital_in | — | — | — | corroborated | |
| OEM-T121-33 | Accelerator pedal position 1 (G79) | analog_in | FT450-A-A21 | White input 2 | analog_in | corroborated | |
| OEM-T121-34 | Accelerator pedal position 1 ground (G79) | sensor_ground | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | corroborated | |
| OEM-T121-35 | Accelerator pedal position 2 (G185) | analog_in | FT450-A-A25 | White input 6 (fuel pressure) | analog_in | corroborated | |
| OEM-T121-36 | Accelerator pedal position 2 ground (G185) | sensor_ground | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | 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 | FT450-A-A4 | Aux 2 | low_side_out | corroborated | |
| OEM-T121-51 | Wideband lambda pump (G39) | wb_ip | — | — | — | corroborated | |
| OEM-T121-52 | Wideband lambda pump (G39) | wb_ip | — | — | — | corroborated | |
| OEM-T121-53 | MAF sensor signal (G70) | analog_in | FT450-A-A20 | White input 1 | analog_in | corroborated | |
| OEM-T121-54 | Road speed signal (VSS) | digital_in | — | — | — | corroborated | |
| OEM-T121-58 | CAN bus low | can_l | FT450-A-A15 | CAN A LOW | can_l | corroborated | |
| OEM-T121-60 | CAN bus high | can_h | FT450-A-A16 | CAN A HIGH | can_h | corroborated | |
| OEM-T121-62 | Battery constant +12V (term 30) | power_in | — | — | — | corroborated | |
| OEM-T121-63 | Post-cat lambda heater (Z29) | low_side_out | FT450-A-A5 | Aux 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 | FT450-A-A6 | Aux 4 (fuel pump / relays) | low_side_out | corroborated | |
| OEM-T121-66 | Secondary-air pump relay (J299) | low_side_out | FT450-A-A3 | Aux 1 | 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 | — | — | — | corroborated | |
| OEM-T121-71 | Wideband lambda Nernst signal (G39) | wb_vs | — | — | — | corroborated | |
| OEM-T121-72 | Accelerator pedal position 1 5V supply (G79) | vref | FT450-A-A14 | +5V sensor supply | vref | corroborated | |
| OEM-T121-73 | Accelerator pedal position 2 5V supply (G185) | vref | FT450-A-A14 | +5V sensor supply | vref | corroborated | |
| OEM-T121-82 | Crank position sensor (G28) | trigger_in | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | corroborated | |
| OEM-T121-83 | Throttle position sensor 5V supply (G187/G188) | vref | FT450-A-A14 | +5V sensor supply | vref | corroborated | |
| OEM-T121-84 | Throttle position sensor 1 (G187) | analog_in | FT450-A-A22 | White input 3 (TPS) | analog_in | corroborated | |
| OEM-T121-85 | Intake air temperature (G42) | temp_in | FT450-A-A26 | White input 7 (air temp) | temp_in | corroborated | |
| OEM-T121-86 | Camshaft position sensor (G40) | trigger_in | FT450-A-A17 | Phase input (cam) | trigger_in | corroborated | |
| OEM-T121-88 | Injector 4 (N33) | injector_out | FT450-A-A2 | Injector 2 (Bank A) | injector_out | corroborated | |
| OEM-T121-89 | Injector 2 (N31) | injector_out | FT450-A-A2 | Injector 2 (Bank A) | 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 | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | corroborated | |
| OEM-T121-91 | Throttle position sensor ground (G187/G188) | sensor_ground | FT450-A-A12 + FT450-A-A18 | Signal ground + RPM reference (crank -) | sensor_ground + trigger_in | corroborated | |
| OEM-T121-92 | Throttle position sensor 2 (G188) | analog_in | — | — | — | corroborated | |
| OEM-T121-93 | Engine coolant temperature (G62) | temp_in | FT450-A-A24 | White input 5 (water temp) | temp_in | corroborated | |
| OEM-T121-94 | Ignition coil 4 (N163) | ignition_out | FT450-A-A11 | Ignition 4 | ignition_out | corroborated | |
| OEM-T121-95 | Ignition coil 2 (N128) | ignition_out | FT450-A-A9 | Ignition 2 | ignition_out | corroborated | |
| OEM-T121-96 | Injector 1 (N30) | injector_out | FT450-A-A1 | Injector 1 (Bank A) | injector_out | corroborated | |
| OEM-T121-97 | Injector 3 (N32) | injector_out | FT450-A-A1 | Injector 1 (Bank A) | injector_out | corroborated | |
| OEM-T121-98 | Cam + boost sensor 5V supply (G40/G31) | vref | FT450-A-A14 | +5V sensor supply | vref | corroborated | |
| OEM-T121-99 | Knock sensor 5V supply (G61/G66) | vref | FT450-A-A14 | +5V sensor supply | 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 | FT450-A-A13 | 0.85 | no route | +12V switched | — | |
| W4 | OEM-T121-1 | SP-GND-1 | 0.85 | no route | ECU ground | — | |
| W5 | OEM-T121-2 | SP-GND-1 | 0.85 | no route | ECU ground | — | |
| W6 | SP-GND-1 | FT450-A-A7 | 0.85 | no route | Power ground | — | |
| W7 | OEM-T121-108 | SP-0V-1 | 0.5 | no route | Sensor ground | — | |
| W8 | OEM-T121-29 | SP-0V-1 | 0.5 | no route | MAF sensor ground (G70) | — | |
| W9 | OEM-T121-34 | SP-0V-1 | 0.5 | no route | Accelerator pedal position 1 ground (G79) | — | |
| W10 | OEM-T121-36 | SP-0V-1 | 0.5 | no route | Accelerator pedal position 2 ground (G185) | — | |
| W11 | OEM-T121-90 | SP-0V-1 | 0.5 | no route | Crank position sensor ground (G28) | — | |
| W12 | OEM-T121-91 | SP-0V-1 | 0.5 | no route | Throttle position sensor ground (G187/G188) | — | |
| W13 | SP-0V-1 | FT450-A-A12 | 0.5 | no route | Signal ground | — | |
| W14 | OEM-T121-72 | SP-5V1-1 | 0.5 | no route | Accelerator pedal position 1 5V supply (G79) | — | |
| W15 | OEM-T121-73 | SP-5V1-1 | 0.5 | no route | Accelerator pedal position 2 5V supply (G185) | — | |
| W16 | OEM-T121-83 | SP-5V1-1 | 0.5 | no route | Throttle position sensor 5V supply (G187/G188) | — | |
| W17 | OEM-T121-98 | SP-5V1-1 | 0.5 | no route | Cam + boost sensor 5V supply (G40/G31) | — | |
| W18 | OEM-T121-99 | SP-5V1-1 | 0.5 | no route | Knock sensor 5V supply (G61/G66) | — | |
| W19 | SP-5V1-1 | FT450-A-A14 | 0.5 | no route | +5V sensor supply | — | |
| W20 | OEM-T121-82 | FT450-A-A18 | 0.5 | no route | Crank position sensor (G28) | — | |
| W21 | SP-0V-1 | FT450-A-A18 | 0.5 | no route | RPM reference (crank -) | — | |
| W22 | OEM-T121-86 | FT450-A-A17 | 0.5 | no route | Camshaft position sensor (G40) | — | |
| W23 | OEM-T121-102 | FT450-A-A8 | 0.5 | no route | Ignition coil 1 (N127) | — | |
| W24 | OEM-T121-95 | FT450-A-A9 | 0.5 | no route | Ignition coil 2 (N128) | — | |
| W25 | OEM-T121-103 | FT450-A-A10 | 0.5 | no route | Ignition coil 3 (N158) | — | |
| W26 | OEM-T121-94 | FT450-A-A11 | 0.5 | no route | Ignition coil 4 (N163) | — | |
| W27 | OEM-T121-96 | FT450-A-A1 | 0.5 | no route | Injector 1 (N30) | — | |
| W28 | OEM-T121-89 | FT450-A-A2 | 0.5 | no route | Injector 2 (N31) | — | |
| W29 | OEM-T121-97 | FT450-A-A1 | 0.5 | no route | Injector 3 (N32) | — | |
| W30 | OEM-T121-88 | FT450-A-A2 | 0.5 | no route | Injector 4 (N33) | — | |
| W31 | OEM-T121-53 | FT450-A-A20 | 0.5 | no route | MAF sensor signal (G70) | — | |
| W32 | OEM-T121-101 | FT450-A-A23 | 0.5 | no route | Boost pressure sensor (G31) | — | |
| W33 | OEM-T121-33 | FT450-A-A21 | 0.5 | no route | Accelerator pedal position 1 (G79) | — | |
| W34 | OEM-T121-84 | FT450-A-A22 | 0.5 | no route | Throttle position sensor 1 (G187) | — | |
| W35 | OEM-T121-35 | FT450-A-A25 | 0.5 | no route | Accelerator pedal position 2 (G185) | — | |
| W36 | OEM-T121-93 | FT450-A-A24 | 0.5 | no route | Engine coolant temperature (G62) | — | |
| W37 | OEM-T121-65 | FT450-A-A6 | 0.5 | no route | Fuel pump relay control | — | |
| W38 | OEM-T121-66 | FT450-A-A3 | 0.5 | no route | Secondary-air pump relay (J299) | — | |
| W39 | OEM-T121-5 | FT450-A-A4 | 0.5 | no route | Wideband lambda heater (Z19) | — | |
| W40 | OEM-T121-63 | FT450-A-A5 | 0.5 | no route | Post-cat lambda heater (Z29) | — | |
| W41 | OEM-T121-85 | FT450-A-A26 | 0.5 | no route | Intake air temperature (G42) | — | |
| W42 | OEM-T121-60 | FT450-A-A16 | 0.5 | no route | CAN bus high | — | |
| W43 | OEM-T121-58 | FT450-A-A15 | 0.5 | no route | CAN bus low | — |
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 (14)
| Severity | Code | Subject | Message |
|---|---|---|---|
| error | NET_MERGED | FT450-A-A1 + OEM-T121-96 + OEM-T121-97 | 2 different OEM functions share one net: OEM-T121-96 Injector 1 (N30); OEM-T121-97 Injector 3 (N32) |
| error | NET_MERGED | FT450-A-A2 + OEM-T121-88 + OEM-T121-89 | 2 different OEM functions share one net: OEM-T121-88 Injector 4 (N33); OEM-T121-89 Injector 2 (N31) |
| 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-T121-92 | Required OEM function "Throttle position sensor 2 (G188)" (analog_in) is not connected to the new ECU. |
| warn | DBW_SHARED_5V | FT450-A-A14 + OEM-T121-72 + OEM-T121-73 + OEM-T121-83 + OEM-T121-98 + OEM-T121-99 + SP-5V1-1 | 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 (FT450-A-A14). On a drive-by-wire car the OEM splits them so one short or fault can't corrupt both throttle/pedal tracks at once. FT450 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 | LOAD_UNKNOWN | FT450-A-A3 | FT450-A-A3 "Aux 1" drives OEM-T121-66 Secondary-air pump relay (J299) (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | LOAD_UNKNOWN | FT450-A-A6 | FT450-A-A6 "Aux 4 (fuel pump / relays)" drives OEM-T121-65 Fuel pump relay control (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | SUPPLY_GROUP | FT450-A-A14 + OEM-T121-72 + OEM-T121-73 + OEM-T121-83 + OEM-T121-98 + OEM-T121-99 + SP-5V1-1 | 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 | NET_FAMILY | OEM-T121-29 ↔ OEM-T121-82 | OEM-T121-29 "MAF sensor ground (G70)" [sensor_ground] is wired to OEM-T121-82 "Crank position sensor (G28)" [trigger_in]. Trigger return tied to sensor/trigger ground: correct for single-ended trigger inputs. |
| info | UNMAPPED | OEM | 17 optional OEM pins are not mapped: OEM-T121-104 Boost control solenoid (N75); 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-T121-51 Wideband lambda pump (G39); OEM-T121-52 Wideband lambda pump (G39); OEM-T121-54 Road speed signal (VSS); OEM-T121-64 EVAP canister valve (N80); OEM-T121-68 Post-cat lambda signal (G130); OEM-T121-69 Post-cat lambda signal (G130); OEM-T121-70 Wideband lambda Nernst signal (G39); OEM-T121-71 Wideband lambda Nernst signal (G39); OEM-T121-9 Secondary-air injection valve (N112) |
Accepted (1)
| Code | Subject | Reason | By |
|---|---|---|---|
| REQUIRED_UNMAPPED | OEM-T121-62 | 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: 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 - 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 FuelTech FT450 - OEM-T121 107: Knock sensor 2 (G66): no free knock input on FuelTech FT450 - OEM-T121 117: Throttle motor G186 (+): needs a paired H-bridge on FuelTech FT450 (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 FuelTech FT450 (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); FuelTech FT450 has no dedicated key-on input - OEM-T121 92: Throttle position sensor 2 (G188): no free tps/analog_0_5 on FuelTech FT450 Not wired: - OEM-T121 62: Battery constant +12V (term 30): FuelTech FT450 has no battery-constant input; not needed - OEM-T121 104: Boost control solenoid (N75): no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-T121 105: Diverter valve (N249): no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-T121 115: VVT camshaft adjustment valve (N205): no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-T121 47: Check engine light (MIL): no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-T121 48: EPC warning light: no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-T121 64: EVAP canister valve (N80): no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-T121 9: Secondary-air injection valve (N112): no free low_side/relay_control/heater_low_side/ls_hs/injector on FuelTech FT450 - OEM-T121 37: Engine speed signal (tacho to cluster): no free tacho/frequency_out/low_side/ls_hs on FuelTech FT450 - OEM-T121 51: Wideband lambda pump (G39): no free wb_ip on FuelTech FT450 - OEM-T121 52: Wideband lambda pump (G39): no free wb_ip on FuelTech FT450 - OEM-T121 70: Wideband lambda Nernst signal (G39): no free wb_vs on FuelTech FT450 - OEM-T121 71: Wideband lambda Nernst signal (G39): no free wb_vs on FuelTech FT450 - OEM-T121 68: Post-cat lambda signal (G130): no free o2_narrowband/analog_0_5 on FuelTech FT450 - OEM-T121 69: Post-cat lambda signal (G130): no free o2_narrowband/analog_0_5 on FuelTech FT450 - OEM-T121 54: Road speed signal (VSS): no free frequency_in/switch_in on FuelTech FT450 - OEM-T121 43: K-line diagnostics (OBD pin 7): no free k_line on FuelTech FT450 - 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 | FuelTech FT450/FT550 ready harness manual (4 & 6 cylinder) — FT450 Connector A pinout | http://ftmanager.fueltech.com.br/downloads/manual/Portugues/Chicote_pronto_FT450-FT550.pdf | — | — | — |
| 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 | — | — | — |