VW Golf Mk4 1.8T 20v (AUM, Bosch ME7.5) DBW → Link G4X MonsoonX (auto)
VW Golf Mk4 1.8T 20v (AUM, Bosch ME7.5) DBW — Link — G4X MonsoonX
⚠ 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 | 6: read the Findings page before cutting any wire |
| Size of the job | 46 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 | G4XMONSOONX-A-A5 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | OEM-T121-1 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | OEM-T121-2 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | SP-GND-1 | G4XMONSOONX-A-A25 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | SP-GND-1 | G4XMONSOONX-A-A34 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | OEM-T121-108 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | OEM-T121-29 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | OEM-T121-34 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | OEM-T121-36 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | OEM-T121-90 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-T121-91 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | SP-0V-1 | G4XMONSOONX-A-A24 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | OEM-T121-72 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | OEM-T121-73 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-T121-83 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-T121-98 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-T121-99 | SP-5V1-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | SP-5V1-1 | G4XMONSOONX-A-A32 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-T121-82 | G4XMONSOONX-A-A8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-T121-86 | G4XMONSOONX-A-A9 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W23 | OEM-T121-106 | G4XMONSOONX-A-A6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W24 | OEM-T121-102 | G4XMONSOONX-A-A13 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W25 | OEM-T121-95 | G4XMONSOONX-A-A12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W26 | OEM-T121-103 | G4XMONSOONX-A-A11 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W27 | OEM-T121-94 | G4XMONSOONX-A-A10 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W28 | OEM-T121-96 | G4XMONSOONX-A-A4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W29 | OEM-T121-89 | G4XMONSOONX-A-A3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W30 | OEM-T121-97 | G4XMONSOONX-A-A2 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W31 | OEM-T121-88 | G4XMONSOONX-A-A1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W32 | OEM-T121-53 | G4XMONSOONX-A-A17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W33 | OEM-T121-101 | G4XMONSOONX-A-A22 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W34 | OEM-T121-33 | G4XMONSOONX-A-A33 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W35 | OEM-T121-84 | G4XMONSOONX-A-A14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W36 | OEM-T121-93 | G4XMONSOONX-A-A15 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W37 | OEM-T121-65 | G4XMONSOONX-A-A21 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W38 | OEM-T121-66 | G4XMONSOONX-A-A20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W39 | OEM-T121-5 | G4XMONSOONX-A-A19 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W40 | OEM-T121-63 | G4XMONSOONX-A-A18 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W41 | OEM-T121-104 | G4XMONSOONX-A-A27 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W42 | OEM-T121-105 | G4XMONSOONX-A-A26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W43 | OEM-T121-85 | G4XMONSOONX-A-A16 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W44 | OEM-T121-54 | G4XMONSOONX-A-A30 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W45 | OEM-T121-60 | G4XMONSOONX-A-A28 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W46 | OEM-T121-58 | G4XMONSOONX-A-A29 | 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 | G4XMONSOONX-A-A24 | G4XMONSOONX-A-A32 | open (OL) | sensor ground must not touch 5 V sensor reference | |
| 2 | G4XMONSOONX-A-A24 | G4XMONSOONX-A-A5 | open (OL) | sensor ground must not touch +12 V supply | |
| 3 | G4XMONSOONX-A-A25 | G4XMONSOONX-A-A32 | open (OL) | power ground must not touch 5 V sensor reference | |
| 4 | G4XMONSOONX-A-A25 | G4XMONSOONX-A-A5 | open (OL) | power ground must not touch +12 V supply | |
| 5 | G4XMONSOONX-A-A5 | G4XMONSOONX-A-A32 | 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
G4XMONSOONX-A
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| A1 | Injector 4 | — | W31 | — | 0.5 | OEM-T121-88 | — | — | — |
| A10 | Ignition 4 | — | W27 | — | 0.5 | OEM-T121-94 | — | — | — |
| A11 | Ignition 3 | — | W26 | — | 0.5 | OEM-T121-103 | — | — | — |
| A12 | Ignition 2 | — | W25 | — | 0.5 | OEM-T121-95 | — | — | — |
| A13 | Ignition 1 | — | W24 | — | 0.5 | OEM-T121-102 | — | — | — |
| A14 | Analog Volt 4 | — | W35 | — | 0.5 | OEM-T121-84 | — | — | — |
| A15 | Analog Temp 1 | — | W36 | — | 0.5 | OEM-T121-93 | — | — | — |
| A16 | Analog Temp 2 | — | W43 | — | 0.5 | OEM-T121-85 | — | — | — |
| A17 | Analog Volt 1 | — | W32 | — | 0.5 | OEM-T121-53 | — | — | — |
| A18 | Aux 4 | — | W40 | — | 0.5 | OEM-T121-63 | — | — | — |
| A19 | Aux 3 | — | W39 | — | 0.5 | OEM-T121-5 | — | — | — |
| A2 | Injector 3 | — | W30 | — | 0.5 | OEM-T121-97 | — | — | — |
| A20 | Aux 2 | — | W38 | — | 0.5 | OEM-T121-66 | — | — | — |
| A21 | Aux 1 | — | W37 | — | 0.5 | OEM-T121-65 | — | — | — |
| A22 | Analog Volt 2 | — | W33 | — | 0.5 | OEM-T121-101 | — | — | — |
| A23 | Digital Input 3 | — | — | — | — | — | — | — | — |
| A24 | Sensor Ground | — | W14 | — | 0.5 | SP-0V-1 | — | — | — |
| A25 | System Ground | — | W6 | — | 0.85 | SP-GND-1 | — | — | — |
| A26 | Aux 6 | — | W42 | — | 0.5 | OEM-T121-105 | — | — | — |
| A27 | Aux 5 | — | W41 | — | 0.5 | OEM-T121-104 | — | — | — |
| A28 | CAN H | — | W45 | — | 0.5 | OEM-T121-60 | — | — | — |
| A29 | CAN L | — | W46 | — | 0.5 | OEM-T121-58 | — | — | — |
| A3 | Injector 2 | — | W29 | — | 0.5 | OEM-T121-89 | — | — | — |
| A30 | Digital Input 1 | — | W44 | — | 0.5 | OEM-T121-54 | — | — | — |
| A31 | Digital Input 2 | — | — | — | — | — | — | — | — |
| A32 | +5V Out | — | W20 | — | 0.5 | SP-5V1-1 | — | — | — |
| A33 | Analog Volt 3 | — | W34 | — | 0.5 | OEM-T121-33 | — | — | — |
| A34 | System Ground | — | W7 | — | 0.85 | SP-GND-1 | — | — | — |
| A4 | Injector 1 | — | W28 | — | 0.5 | OEM-T121-96 | — | — | — |
| A5 | +14V ECU Power | — | W3 | — | 0.85 | SP-14V-1 | — | — | — |
| A6 | Knock 1 / Digital Input 4 | — | W23 | — | 0.5 | OEM-T121-106 | — | — | — |
| A7 | Shield Ground | — | — | — | — | — | — | — | — |
| A8 | Trigger 1 | — | W21 | — | 0.5 | OEM-T121-82 | — | — | — |
| A9 | Trigger 2 | — | W22 | — | 0.5 | OEM-T121-86 | — | — | — |
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) | — | W33 | — | 0.5 | G4XMONSOONX-A-A22 | — | — | — |
| 102 | Ignition coil 1 (N127) | — | W24 | — | 0.5 | G4XMONSOONX-A-A13 | — | — | — |
| 103 | Ignition coil 3 (N158) | — | W26 | — | 0.5 | G4XMONSOONX-A-A11 | — | — | — |
| 104 | Boost control solenoid (N75) | — | W41 | — | 0.5 | G4XMONSOONX-A-A27 | — | — | — |
| 105 | Diverter valve (N249) | — | W42 | — | 0.5 | G4XMONSOONX-A-A26 | — | — | — |
| 106 | Knock sensor 1 (G61) | — | W23 | — | 0.5 | G4XMONSOONX-A-A6 | — | — | — |
| 107 | Knock sensor 2 (G66) | — | — | — | — | — | — | — | — |
| 108 | Sensor ground | — | W8 | — | 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) | — | W9 | — | 0.5 | SP-0V-1 | — | — | — |
| 3 | Ignition switch +12V (term 15) | — | — | — | — | — | — | — | — |
| 33 | Accelerator pedal position 1 (G79) | — | W34 | — | 0.5 | G4XMONSOONX-A-A33 | — | — | — |
| 34 | Accelerator pedal position 1 ground (G79) | — | W10 | — | 0.5 | SP-0V-1 | — | — | — |
| 35 | Accelerator pedal position 2 (G185) | — | — | — | — | — | — | — | — |
| 36 | Accelerator pedal position 2 ground (G185) | — | W11 | — | 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 | G4XMONSOONX-A-A19 | — | — | — |
| 51 | Wideband lambda pump (G39) | — | — | — | — | — | — | — | — |
| 52 | Wideband lambda pump (G39) | — | — | — | — | — | — | — | — |
| 53 | MAF sensor signal (G70) | — | W32 | — | 0.5 | G4XMONSOONX-A-A17 | — | — | — |
| 54 | Road speed signal (VSS) | — | W44 | — | 0.5 | G4XMONSOONX-A-A30 | — | — | — |
| 58 | CAN bus low | — | W46 | — | 0.5 | G4XMONSOONX-A-A29 | — | — | — |
| 60 | CAN bus high | — | W45 | — | 0.5 | G4XMONSOONX-A-A28 | — | — | — |
| 62 | Battery constant +12V (term 30) | — | — | — | — | — | — | — | — |
| 63 | Post-cat lambda heater (Z29) | — | W40 | — | 0.5 | G4XMONSOONX-A-A18 | — | — | — |
| 64 | EVAP canister valve (N80) | — | — | — | — | — | — | — | — |
| 65 | Fuel pump relay control | — | W37 | — | 0.5 | G4XMONSOONX-A-A21 | — | — | — |
| 66 | Secondary-air pump relay (J299) | — | W38 | — | 0.5 | G4XMONSOONX-A-A20 | — | — | — |
| 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) | — | W15 | — | 0.5 | SP-5V1-1 | — | — | — |
| 73 | Accelerator pedal position 2 5V supply (G185) | — | W16 | — | 0.5 | SP-5V1-1 | — | — | — |
| 82 | Crank position sensor (G28) | — | W21 | — | 0.5 | G4XMONSOONX-A-A8 | — | — | — |
| 83 | Throttle position sensor 5V supply (G187/G188) | — | W17 | — | 0.5 | SP-5V1-1 | — | — | — |
| 84 | Throttle position sensor 1 (G187) | — | W35 | — | 0.5 | G4XMONSOONX-A-A14 | — | — | — |
| 85 | Intake air temperature (G42) | — | W43 | — | 0.5 | G4XMONSOONX-A-A16 | — | — | — |
| 86 | Camshaft position sensor (G40) | — | W22 | — | 0.5 | G4XMONSOONX-A-A9 | — | — | — |
| 88 | Injector 4 (N33) | — | W31 | — | 0.5 | G4XMONSOONX-A-A1 | — | — | — |
| 89 | Injector 2 (N31) | — | W29 | — | 0.5 | G4XMONSOONX-A-A3 | — | — | — |
| 9 | Secondary-air injection valve (N112) | — | — | — | — | — | — | — | — |
| 90 | Crank position sensor ground (G28) | — | W12 | — | 0.5 | SP-0V-1 | — | — | — |
| 91 | Throttle position sensor ground (G187/G188) | — | W13 | — | 0.5 | SP-0V-1 | — | — | — |
| 92 | Throttle position sensor 2 (G188) | — | — | — | — | — | — | — | — |
| 93 | Engine coolant temperature (G62) | — | W36 | — | 0.5 | G4XMONSOONX-A-A15 | — | — | — |
| 94 | Ignition coil 4 (N163) | — | W27 | — | 0.5 | G4XMONSOONX-A-A10 | — | — | — |
| 95 | Ignition coil 2 (N128) | — | W25 | — | 0.5 | G4XMONSOONX-A-A12 | — | — | — |
| 96 | Injector 1 (N30) | — | W28 | — | 0.5 | G4XMONSOONX-A-A4 | — | — | — |
| 97 | Injector 3 (N32) | — | W30 | — | 0.5 | G4XMONSOONX-A-A2 | — | — | — |
| 98 | Cam + boost sensor 5V supply (G40/G31) | — | W18 | — | 0.5 | SP-5V1-1 | — | — | — |
| 99 | Knock sensor 5V supply (G61/G66) | — | W19 | — | 0.5 | SP-5V1-1 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W8 | — | 0.5 | OEM-T121-108 | — | — | — |
| 1 | — | — | W9 | — | 0.5 | OEM-T121-29 | — | — | — |
| 1 | — | — | W10 | — | 0.5 | OEM-T121-34 | — | — | — |
| 1 | — | — | W11 | — | 0.5 | OEM-T121-36 | — | — | — |
| 1 | — | — | W12 | — | 0.5 | OEM-T121-90 | — | — | — |
| 1 | — | — | W13 | — | 0.5 | OEM-T121-91 | — | — | — |
| 1 | — | — | W14 | — | 0.5 | G4XMONSOONX-A-A24 | — | — | — |
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 | G4XMONSOONX-A-A5 | — | — | — |
SP-5V1
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W15 | — | 0.5 | OEM-T121-72 | — | — | — |
| 1 | — | — | W16 | — | 0.5 | OEM-T121-73 | — | — | — |
| 1 | — | — | W17 | — | 0.5 | OEM-T121-83 | — | — | — |
| 1 | — | — | W18 | — | 0.5 | OEM-T121-98 | — | — | — |
| 1 | — | — | W19 | — | 0.5 | OEM-T121-99 | — | — | — |
| 1 | — | — | W20 | — | 0.5 | G4XMONSOONX-A-A32 | — | — | — |
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 | G4XMONSOONX-A-A25 | — | — | — |
| 1 | — | — | W7 | — | 0.85 | G4XMONSOONX-A-A34 | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| OEM-T121-1 | ECU ground | ground | G4XMONSOONX-A-A25 + G4XMONSOONX-A-A34 | System Ground + System Ground | ground | corroborated | |
| OEM-T121-101 | Boost pressure sensor (G31) | analog_in | G4XMONSOONX-A-A22 | Analog Volt 2 | analog_in | corroborated | |
| OEM-T121-102 | Ignition coil 1 (N127) | ignition_out | G4XMONSOONX-A-A13 | Ignition 1 | ignition_out | corroborated | |
| OEM-T121-103 | Ignition coil 3 (N158) | ignition_out | G4XMONSOONX-A-A11 | Ignition 3 | ignition_out | corroborated | |
| OEM-T121-104 | Boost control solenoid (N75) | low_side_out | G4XMONSOONX-A-A27 | Aux 5 | low_side_out | corroborated | |
| OEM-T121-105 | Diverter valve (N249) | low_side_out | G4XMONSOONX-A-A26 | Aux 6 | low_side_out | corroborated | |
| OEM-T121-106 | Knock sensor 1 (G61) | knock_in | G4XMONSOONX-A-A6 | Knock 1 / Digital Input 4 | knock_in | corroborated | |
| OEM-T121-107 | Knock sensor 2 (G66) | knock_in | — | — | — | corroborated | |
| OEM-T121-108 | Sensor ground | sensor_ground | G4XMONSOONX-A-A24 | 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 | G4XMONSOONX-A-A5 | +14V ECU Power | power_in | corroborated | |
| OEM-T121-2 | ECU ground | ground | G4XMONSOONX-A-A25 + G4XMONSOONX-A-A34 | System Ground + System Ground | ground | corroborated | |
| OEM-T121-21 | ECM power (J271 relay feed) | power_in | G4XMONSOONX-A-A5 | +14V ECU Power | power_in | corroborated | |
| OEM-T121-27 | MAF sensor supply (G70) | power_in | — | — | — | corroborated | |
| OEM-T121-29 | MAF sensor ground (G70) | sensor_ground | G4XMONSOONX-A-A24 | 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 | G4XMONSOONX-A-A33 | Analog Volt 3 | analog_in | corroborated | |
| OEM-T121-34 | Accelerator pedal position 1 ground (G79) | sensor_ground | G4XMONSOONX-A-A24 | Sensor Ground | sensor_ground | corroborated | |
| OEM-T121-35 | Accelerator pedal position 2 (G185) | analog_in | — | — | — | corroborated | |
| OEM-T121-36 | Accelerator pedal position 2 ground (G185) | sensor_ground | G4XMONSOONX-A-A24 | 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 | G4XMONSOONX-A-A19 | Aux 3 | 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 | G4XMONSOONX-A-A17 | Analog Volt 1 | analog_in | corroborated | |
| OEM-T121-54 | Road speed signal (VSS) | digital_in | G4XMONSOONX-A-A30 | Digital Input 1 | digital_in | corroborated | |
| OEM-T121-58 | CAN bus low | can_l | G4XMONSOONX-A-A29 | CAN L | can_l | corroborated | |
| OEM-T121-60 | CAN bus high | can_h | G4XMONSOONX-A-A28 | CAN H | 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 | G4XMONSOONX-A-A18 | Aux 4 | 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 | G4XMONSOONX-A-A21 | Aux 1 | low_side_out | corroborated | |
| OEM-T121-66 | Secondary-air pump relay (J299) | low_side_out | G4XMONSOONX-A-A20 | Aux 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 | — | — | — | corroborated | |
| OEM-T121-71 | Wideband lambda Nernst signal (G39) | wb_vs | — | — | — | corroborated | |
| OEM-T121-72 | Accelerator pedal position 1 5V supply (G79) | vref | G4XMONSOONX-A-A32 | +5V Out | vref | corroborated | |
| OEM-T121-73 | Accelerator pedal position 2 5V supply (G185) | vref | G4XMONSOONX-A-A32 | +5V Out | vref | corroborated | |
| OEM-T121-82 | Crank position sensor (G28) | trigger_in | G4XMONSOONX-A-A8 | Trigger 1 | trigger_in | corroborated | |
| OEM-T121-83 | Throttle position sensor 5V supply (G187/G188) | vref | G4XMONSOONX-A-A32 | +5V Out | vref | corroborated | |
| OEM-T121-84 | Throttle position sensor 1 (G187) | analog_in | G4XMONSOONX-A-A14 | Analog Volt 4 | analog_in | corroborated | |
| OEM-T121-85 | Intake air temperature (G42) | temp_in | G4XMONSOONX-A-A16 | Analog Temp 2 | temp_in | corroborated | |
| OEM-T121-86 | Camshaft position sensor (G40) | trigger_in | G4XMONSOONX-A-A9 | Trigger 2 | trigger_in | corroborated | |
| OEM-T121-88 | Injector 4 (N33) | injector_out | G4XMONSOONX-A-A1 | Injector 4 | injector_out | corroborated | |
| OEM-T121-89 | Injector 2 (N31) | injector_out | G4XMONSOONX-A-A3 | Injector 2 | 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 | G4XMONSOONX-A-A24 | Sensor Ground | sensor_ground | corroborated | |
| OEM-T121-91 | Throttle position sensor ground (G187/G188) | sensor_ground | G4XMONSOONX-A-A24 | Sensor Ground | sensor_ground | corroborated | |
| OEM-T121-92 | Throttle position sensor 2 (G188) | analog_in | — | — | — | corroborated | |
| OEM-T121-93 | Engine coolant temperature (G62) | temp_in | G4XMONSOONX-A-A15 | Analog Temp 1 | temp_in | corroborated | |
| OEM-T121-94 | Ignition coil 4 (N163) | ignition_out | G4XMONSOONX-A-A10 | Ignition 4 | ignition_out | corroborated | |
| OEM-T121-95 | Ignition coil 2 (N128) | ignition_out | G4XMONSOONX-A-A12 | Ignition 2 | ignition_out | corroborated | |
| OEM-T121-96 | Injector 1 (N30) | injector_out | G4XMONSOONX-A-A4 | Injector 1 | injector_out | corroborated | |
| OEM-T121-97 | Injector 3 (N32) | injector_out | G4XMONSOONX-A-A2 | Injector 3 | injector_out | corroborated | |
| OEM-T121-98 | Cam + boost sensor 5V supply (G40/G31) | vref | G4XMONSOONX-A-A32 | +5V Out | vref | corroborated | |
| OEM-T121-99 | Knock sensor 5V supply (G61/G66) | vref | G4XMONSOONX-A-A32 | +5V Out | 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 | G4XMONSOONX-A-A5 | 0.85 | no route | +14V ECU Power | — | |
| 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 | G4XMONSOONX-A-A25 | 0.85 | no route | System Ground | — | |
| W7 | SP-GND-1 | G4XMONSOONX-A-A34 | 0.85 | no route | System Ground | — | |
| W8 | OEM-T121-108 | SP-0V-1 | 0.5 | no route | Sensor ground | — | |
| W9 | OEM-T121-29 | SP-0V-1 | 0.5 | no route | MAF sensor ground (G70) | — | |
| W10 | OEM-T121-34 | SP-0V-1 | 0.5 | no route | Accelerator pedal position 1 ground (G79) | — | |
| W11 | OEM-T121-36 | SP-0V-1 | 0.5 | no route | Accelerator pedal position 2 ground (G185) | — | |
| W12 | OEM-T121-90 | SP-0V-1 | 0.5 | no route | Crank position sensor ground (G28) | — | |
| W13 | OEM-T121-91 | SP-0V-1 | 0.5 | no route | Throttle position sensor ground (G187/G188) | — | |
| W14 | SP-0V-1 | G4XMONSOONX-A-A24 | 0.5 | no route | Sensor Ground | — | |
| W15 | OEM-T121-72 | SP-5V1-1 | 0.5 | no route | Accelerator pedal position 1 5V supply (G79) | — | |
| W16 | OEM-T121-73 | SP-5V1-1 | 0.5 | no route | Accelerator pedal position 2 5V supply (G185) | — | |
| W17 | OEM-T121-83 | SP-5V1-1 | 0.5 | no route | Throttle position sensor 5V supply (G187/G188) | — | |
| W18 | OEM-T121-98 | SP-5V1-1 | 0.5 | no route | Cam + boost sensor 5V supply (G40/G31) | — | |
| W19 | OEM-T121-99 | SP-5V1-1 | 0.5 | no route | Knock sensor 5V supply (G61/G66) | — | |
| W20 | SP-5V1-1 | G4XMONSOONX-A-A32 | 0.5 | no route | +5V Out | — | |
| W21 | OEM-T121-82 | G4XMONSOONX-A-A8 | 0.5 | no route | Crank position sensor (G28) | — | |
| W22 | OEM-T121-86 | G4XMONSOONX-A-A9 | 0.5 | no route | Camshaft position sensor (G40) | — | |
| W23 | OEM-T121-106 | G4XMONSOONX-A-A6 | 0.5 | no route | Knock sensor 1 (G61) | — | |
| W24 | OEM-T121-102 | G4XMONSOONX-A-A13 | 0.5 | no route | Ignition coil 1 (N127) | — | |
| W25 | OEM-T121-95 | G4XMONSOONX-A-A12 | 0.5 | no route | Ignition coil 2 (N128) | — | |
| W26 | OEM-T121-103 | G4XMONSOONX-A-A11 | 0.5 | no route | Ignition coil 3 (N158) | — | |
| W27 | OEM-T121-94 | G4XMONSOONX-A-A10 | 0.5 | no route | Ignition coil 4 (N163) | — | |
| W28 | OEM-T121-96 | G4XMONSOONX-A-A4 | 0.5 | no route | Injector 1 (N30) | — | |
| W29 | OEM-T121-89 | G4XMONSOONX-A-A3 | 0.5 | no route | Injector 2 (N31) | — | |
| W30 | OEM-T121-97 | G4XMONSOONX-A-A2 | 0.5 | no route | Injector 3 (N32) | — | |
| W31 | OEM-T121-88 | G4XMONSOONX-A-A1 | 0.5 | no route | Injector 4 (N33) | — | |
| W32 | OEM-T121-53 | G4XMONSOONX-A-A17 | 0.5 | no route | MAF sensor signal (G70) | — | |
| W33 | OEM-T121-101 | G4XMONSOONX-A-A22 | 0.5 | no route | Boost pressure sensor (G31) | — | |
| W34 | OEM-T121-33 | G4XMONSOONX-A-A33 | 0.5 | no route | Accelerator pedal position 1 (G79) | — | |
| W35 | OEM-T121-84 | G4XMONSOONX-A-A14 | 0.5 | no route | Throttle position sensor 1 (G187) | — | |
| W36 | OEM-T121-93 | G4XMONSOONX-A-A15 | 0.5 | no route | Engine coolant temperature (G62) | — | |
| W37 | OEM-T121-65 | G4XMONSOONX-A-A21 | 0.5 | no route | Fuel pump relay control | — | |
| W38 | OEM-T121-66 | G4XMONSOONX-A-A20 | 0.5 | no route | Secondary-air pump relay (J299) | — | |
| W39 | OEM-T121-5 | G4XMONSOONX-A-A19 | 0.5 | no route | Wideband lambda heater (Z19) | — | |
| W40 | OEM-T121-63 | G4XMONSOONX-A-A18 | 0.5 | no route | Post-cat lambda heater (Z29) | — | |
| W41 | OEM-T121-104 | G4XMONSOONX-A-A27 | 0.5 | no route | Boost control solenoid (N75) | — | |
| W42 | OEM-T121-105 | G4XMONSOONX-A-A26 | 0.5 | no route | Diverter valve (N249) | — | |
| W43 | OEM-T121-85 | G4XMONSOONX-A-A16 | 0.5 | no route | Intake air temperature (G42) | — | |
| W44 | OEM-T121-54 | G4XMONSOONX-A-A30 | 0.5 | no route | Road speed signal (VSS) | — | |
| W45 | OEM-T121-60 | G4XMONSOONX-A-A28 | 0.5 | no route | CAN bus high | — | |
| W46 | OEM-T121-58 | G4XMONSOONX-A-A29 | 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 (11)
| Severity | Code | Subject | Message |
|---|---|---|---|
| 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-T121-35 | Required OEM function "Accelerator pedal position 2 (G185)" (analog_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 | G4XMONSOONX-A-A32 + 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 (G4XMONSOONX-A-A32). On a drive-by-wire car the OEM splits them so one short or fault can't corrupt both throttle/pedal tracks at once. G4X MonsoonX 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 | G4XMONSOONX-A-A20 | G4XMONSOONX-A-A20 "Aux 2" 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 | G4XMONSOONX-A-A21 | G4XMONSOONX-A-A21 "Aux 1" 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 | G4XMONSOONX-A-A32 + 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 | UNMAPPED | OEM | 14 optional OEM pins are not mapped: 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-T121-64 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: - Drive-by-wire only with an add-on: Link RET 115-1000 - This car has VW/Audi Immobilizer (delete/bypass for standalone) immobilizer; needs a delete/bypass - Trigger pattern needs a workaround: The 1.8T 20v (ME7.5, EA113) is 60-2 crank + Hall cam; Link's generic Multi/Missing-tooth 60-2 runs it and Link's DI KB covers the VAG EA113 family. No "VW 1.8T" mode name is published online. 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 107: Knock sensor 2 (G66): no free knock input on Link G4X MonsoonX - OEM-T121 117: Throttle motor G186 (+): needs a paired H-bridge on Link G4X MonsoonX (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 Link G4X MonsoonX (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); Link G4X MonsoonX has no dedicated key-on input - OEM-T121 35: Accelerator pedal position 2 (G185): no free tps/analog_0_5 on Link G4X MonsoonX - OEM-T121 92: Throttle position sensor 2 (G188): no free tps/analog_0_5 on Link G4X MonsoonX Not wired: - OEM-T121 62: Battery constant +12V (term 30): Link G4X MonsoonX has no battery-constant input; not needed - OEM-T121 115: VVT camshaft adjustment valve (N205): no free low_side/relay_control/heater_low_side/ls_hs/injector on Link G4X MonsoonX - OEM-T121 47: Check engine light (MIL): no free low_side/relay_control/heater_low_side/ls_hs/injector on Link G4X MonsoonX - OEM-T121 48: EPC warning light: no free low_side/relay_control/heater_low_side/ls_hs/injector on Link G4X MonsoonX - OEM-T121 64: EVAP canister valve (N80): no free low_side/relay_control/heater_low_side/ls_hs/injector on Link G4X MonsoonX - OEM-T121 9: Secondary-air injection valve (N112): no free low_side/relay_control/heater_low_side/ls_hs/injector on Link G4X MonsoonX - OEM-T121 37: Engine speed signal (tacho to cluster): no free tacho/frequency_out/low_side/ls_hs on Link G4X MonsoonX - OEM-T121 51: Wideband lambda pump (G39): no free wb_ip on Link G4X MonsoonX - OEM-T121 52: Wideband lambda pump (G39): no free wb_ip on Link G4X MonsoonX - OEM-T121 70: Wideband lambda Nernst signal (G39): no free wb_vs on Link G4X MonsoonX - OEM-T121 71: Wideband lambda Nernst signal (G39): no free wb_vs on Link G4X MonsoonX - OEM-T121 68: Post-cat lambda signal (G130): no free o2_narrowband/analog_0_5 on Link G4X MonsoonX - OEM-T121 69: Post-cat lambda signal (G130): no free o2_narrowband/analog_0_5 on Link G4X MonsoonX - OEM-T121 43: K-line diagnostics (OBD pin 7): no free k_line on Link G4X MonsoonX - 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 | Link: G4X MonsoonX quickstart + RET 115-1000 | https://linkecu.com/documentation/MonsoonXQuickstartGuide.pdf | archive | 2026-10-05 | e8d432b273d6 |
| 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 | YourSpec: Link G4X MonsoonX flying-lead harness wiring list | https://wpm.yourspec.com/projects/view/1469 | — | — | — |
| 3 | community_copy | vwressources: Bosch Motronic ME7.5 (AMK/ARY/AUQ/ARX/AUM) T121 pinout | https://www.vwressources.planethoster.world/me75_pinout.html | — | — | — |