VW Golf/Jetta Mk2 1.8 8v Digifant II → FuelTech FT450 (auto)
VW Golf/Jetta Mk2 1.8 8v Digifant II — FuelTech — FT450
⚠ NOT CHECKED. Don't build from this.
Drawn by Michael Gnankou · Rev 0 · draft · 2026-10-12
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 | 1: read the Findings page before cutting any wire |
| Size of the job | 22 wires · 5 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-A-14 | SP-14V-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W2 | SP-14V-1 | FT450-A-A13 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W3 | OEM-A-13 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W4 | OEM-A-19 | SP-GND-1 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W5 | SP-GND-1 | FT450-A-A7 | 0.85 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W6 | OEM-A-5 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W7 | OEM-A-6 | SP-0V-1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W8 | SP-0V-1 | FT450-A-A12 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W9 | OEM-A-17 | FT450-A-A14 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W10 | OEM-A-18 | FT450-A-A17 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W11 | OEM-A-25 | FT450-A-A8 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W12 | OEM-A-12 | FT450-A-A1 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W13 | OEM-A-3 | FT450-A-A6 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W14 | OEM-A-21 | FT450-A-A20 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W15 | OEM-A-10 | FT450-A-A24 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W16 | OEM-A-22 | FT450-A-A3 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W17 | OEM-A-23 | FT450-A-A4 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W18 | OEM-A-2 | FT450-A-A21 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W19 | OEM-A-9 | FT450-A-A26 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W20 | OEM-A-1 | FT450-A-A22 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W21 | OEM-A-11 | FT450-A-A23 | 0.5 | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | ☐ | |
| W22 | OEM-A-16 | FT450-A-A25 | 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-A13 | FT450-A-A12 | open (OL) | +12 V supply must not touch sensor ground | |
| 2 | FT450-A-A14 | FT450-A-A12 | open (OL) | 5 V sensor reference must not touch sensor ground | |
| 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) | — | W12 | — | 0.5 | OEM-A-12 | — | — | — |
| A10 | Ignition 3 | — | — | — | — | — | — | — | — |
| A11 | Ignition 4 | — | — | — | — | — | — | — | — |
| A12 | Signal ground | — | W8 | — | 0.5 | SP-0V-1 | — | — | — |
| A13 | +12V switched | — | W2 | — | 0.85 | SP-14V-1 | — | — | — |
| A14 | +5V sensor supply | — | W9 | — | 0.5 | OEM-A-17 | — | — | — |
| A15 | CAN A LOW | — | — | — | — | — | — | — | — |
| A16 | CAN A HIGH | — | — | — | — | — | — | — | — |
| A17 | Phase input (cam) | — | W10 | — | 0.5 | OEM-A-18 | — | — | — |
| A18 | RPM reference (crank -) | — | — | — | — | — | — | — | — |
| A19 | RPM signal (crank +) | — | — | — | — | — | — | — | — |
| A2 | Injector 2 (Bank A) | — | — | — | — | — | — | — | — |
| A20 | White input 1 | — | W14 | — | 0.5 | OEM-A-21 | — | — | — |
| A21 | White input 2 | — | W18 | — | 0.5 | OEM-A-2 | — | — | — |
| A22 | White input 3 (TPS) | — | W20 | — | 0.5 | OEM-A-1 | — | — | — |
| A23 | White input 4 (oil pressure) | — | W21 | — | 0.5 | OEM-A-11 | — | — | — |
| A24 | White input 5 (water temp) | — | W15 | — | 0.5 | OEM-A-10 | — | — | — |
| A25 | White input 6 (fuel pressure) | — | W22 | — | 0.5 | OEM-A-16 | — | — | — |
| A26 | White input 7 (air temp) | — | W19 | — | 0.5 | OEM-A-9 | — | — | — |
| A3 | Aux 1 | — | W16 | — | 0.5 | OEM-A-22 | — | — | — |
| A4 | Aux 2 | — | W17 | — | 0.5 | OEM-A-23 | — | — | — |
| A5 | Aux 3 | — | — | — | — | — | — | — | — |
| A6 | Aux 4 (fuel pump / relays) | — | W13 | — | 0.5 | OEM-A-3 | — | — | — |
| A7 | Power ground | — | W5 | — | 0.85 | SP-GND-1 | — | — | — |
| A8 | Ignition 1 | — | W11 | — | 0.5 | OEM-A-25 | — | — | — |
| A9 | Ignition 2 | — | — | — | — | — | — | — | — |
OEM-A
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Starter signal (term 50) | — | W20 | — | 0.5 | FT450-A-A22 | — | — | — |
| 10 | Coolant temperature sensor | — | W15 | — | 0.5 | FT450-A-A24 | — | — | — |
| 11 | Idle/WOT throttle switch | — | W21 | — | 0.5 | FT450-A-A23 | — | — | — |
| 12 | Injector driver (batch, all 4) | — | W12 | — | 0.5 | FT450-A-A1 | — | — | — |
| 13 | Ground | — | W3 | — | 0.85 | SP-GND-1 | — | — | — |
| 14 | ECU power (control-unit relay) | — | W1 | — | 0.85 | SP-14V-1 | — | — | — |
| 16 | A/C compressor signal | — | W22 | — | 0.5 | FT450-A-A25 | — | — | — |
| 17 | AFM potentiometer supply | — | W9 | — | 0.5 | FT450-A-A14 | — | — | — |
| 18 | Hall sender signal (engine speed) | — | W10 | — | 0.5 | FT450-A-A17 | — | — | — |
| 19 | Ground | — | W4 | — | 0.85 | SP-GND-1 | — | — | — |
| 2 | Oxygen (lambda) sensor signal | — | W18 | — | 0.5 | FT450-A-A21 | — | — | — |
| 21 | AFM signal | — | W14 | — | 0.5 | FT450-A-A20 | — | — | — |
| 22 | Idle stabilizer valve coil 1 | — | W16 | — | 0.5 | FT450-A-A3 | — | — | — |
| 23 | Idle stabilizer valve coil 2 | — | W17 | — | 0.5 | FT450-A-A4 | — | — | — |
| 25 | Ignition timing signal to TCI | — | W11 | — | 0.5 | FT450-A-A8 | — | — | — |
| 3 | Fuel pump relay control | — | W13 | — | 0.5 | FT450-A-A6 | — | — | — |
| 4 | Knock sensor signal | — | — | — | — | — | — | — | — |
| 5 | Knock sensor return | — | W6 | — | 0.5 | SP-0V-1 | — | — | — |
| 6 | Sensor ground (CTS/Hall/AFM/throttle) | — | W7 | — | 0.5 | SP-0V-1 | — | — | — |
| 7 | Knock sensor shield | — | — | — | — | — | — | — | — |
| 8 | Hall sender supply (distributor) | — | — | — | — | — | — | — | — |
| 9 | Intake air temperature sensor | — | W19 | — | 0.5 | FT450-A-A26 | — | — | — |
SP-0V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W6 | — | 0.5 | OEM-A-5 | — | — | — |
| 1 | — | — | W7 | — | 0.5 | OEM-A-6 | — | — | — |
| 1 | — | — | W8 | — | 0.5 | FT450-A-A12 | — | — | — |
SP-14V
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W1 | — | 0.85 | OEM-A-14 | — | — | — |
| 1 | — | — | W2 | — | 0.85 | FT450-A-A13 | — | — | — |
SP-GND
| Cavity | Function | Signal | Wire | Colour | Gauge (mm²) | Destination | Terminal | Seal | Plug |
|---|---|---|---|---|---|---|---|---|---|
| 1 | — | — | W3 | — | 0.85 | OEM-A-13 | — | — | — |
| 1 | — | — | W4 | — | 0.85 | OEM-A-19 | — | — | — |
| 1 | — | — | W5 | — | 0.85 | FT450-A-A7 | — | — | — |
Pin map
| OEM point | OEM function | OEM family | Target point | Target function | Target family | Wire colour | Evidence |
|---|---|---|---|---|---|---|---|
| OEM-A-1 | Starter signal (term 50) | digital_in | FT450-A-A22 | White input 3 (TPS) | analog_in | corroborated | |
| OEM-A-10 | Coolant temperature sensor | temp_in | FT450-A-A24 | White input 5 (water temp) | temp_in | corroborated | |
| OEM-A-11 | Idle/WOT throttle switch | digital_in | FT450-A-A23 | White input 4 (oil pressure) | analog_in | corroborated | |
| OEM-A-12 | Injector driver (batch, all 4) | injector_out | FT450-A-A1 | Injector 1 (Bank A) | injector_out | corroborated | |
| OEM-A-13 | Ground | ground | FT450-A-A7 | Power ground | ground | corroborated | |
| OEM-A-14 | ECU power (control-unit relay) | power_in | FT450-A-A13 | +12V switched | power_in | corroborated | |
| OEM-A-16 | A/C compressor signal | digital_in | FT450-A-A25 | White input 6 (fuel pressure) | analog_in | corroborated | |
| OEM-A-17 | AFM potentiometer supply | vref | FT450-A-A14 | +5V sensor supply | vref | corroborated | |
| OEM-A-18 | Hall sender signal (engine speed) | trigger_in | FT450-A-A17 | Phase input (cam) | trigger_in | corroborated | |
| OEM-A-19 | Ground | ground | FT450-A-A7 | Power ground | ground | corroborated | |
| OEM-A-2 | Oxygen (lambda) sensor signal | lambda_nb_in | FT450-A-A21 | White input 2 | analog_in | corroborated | |
| OEM-A-21 | AFM signal | analog_in | FT450-A-A20 | White input 1 | analog_in | corroborated | |
| OEM-A-22 | Idle stabilizer valve coil 1 | low_side_out | FT450-A-A3 | Aux 1 | low_side_out | corroborated | |
| OEM-A-23 | Idle stabilizer valve coil 2 | low_side_out | FT450-A-A4 | Aux 2 | low_side_out | corroborated | |
| OEM-A-25 | Ignition timing signal to TCI | ignition_out | FT450-A-A8 | Ignition 1 | ignition_out | corroborated | |
| OEM-A-3 | Fuel pump relay control | low_side_out | FT450-A-A6 | Aux 4 (fuel pump / relays) | low_side_out | corroborated | |
| OEM-A-4 | Knock sensor signal | knock_in | — | — | — | corroborated | |
| OEM-A-5 | Knock sensor return | sensor_ground | FT450-A-A12 | Signal ground | sensor_ground | corroborated | |
| OEM-A-6 | Sensor ground (CTS/Hall/AFM/throttle) | sensor_ground | FT450-A-A12 | Signal ground | sensor_ground | corroborated | |
| OEM-A-7 | Knock sensor shield | shield | — | — | — | corroborated | |
| OEM-A-8 | Hall sender supply (distributor) | power_in | — | — | — | corroborated | |
| OEM-A-9 | Intake air temperature sensor | temp_in | FT450-A-A26 | White input 7 (air temp) | temp_in | corroborated |
Cut list
| Wire | From | To | Gauge (mm²) | Colour | Length | Signal | Ident |
|---|---|---|---|---|---|---|---|
| W1 | OEM-A-14 | SP-14V-1 | 0.85 | no route | ECU power (control-unit relay) | — | |
| W2 | SP-14V-1 | FT450-A-A13 | 0.85 | no route | +12V switched | — | |
| W3 | OEM-A-13 | SP-GND-1 | 0.85 | no route | Ground | — | |
| W4 | OEM-A-19 | SP-GND-1 | 0.85 | no route | Ground | — | |
| W5 | SP-GND-1 | FT450-A-A7 | 0.85 | no route | Power ground | — | |
| W6 | OEM-A-5 | SP-0V-1 | 0.5 | no route | Knock sensor return | — | |
| W7 | OEM-A-6 | SP-0V-1 | 0.5 | no route | Sensor ground (CTS/Hall/AFM/throttle) | — | |
| W8 | SP-0V-1 | FT450-A-A12 | 0.5 | no route | Signal ground | — | |
| W9 | OEM-A-17 | FT450-A-A14 | 0.5 | no route | AFM potentiometer supply | — | |
| W10 | OEM-A-18 | FT450-A-A17 | 0.5 | no route | Hall sender signal (engine speed) | — | |
| W11 | OEM-A-25 | FT450-A-A8 | 0.5 | no route | Ignition timing signal to TCI | — | |
| W12 | OEM-A-12 | FT450-A-A1 | 0.5 | no route | Injector driver (batch, all 4) | — | |
| W13 | OEM-A-3 | FT450-A-A6 | 0.5 | no route | Fuel pump relay control | — | |
| W14 | OEM-A-21 | FT450-A-A20 | 0.5 | no route | AFM signal | — | |
| W15 | OEM-A-10 | FT450-A-A24 | 0.5 | no route | Coolant temperature sensor | — | |
| W16 | OEM-A-22 | FT450-A-A3 | 0.5 | no route | Idle stabilizer valve coil 1 | — | |
| W17 | OEM-A-23 | FT450-A-A4 | 0.5 | no route | Idle stabilizer valve coil 2 | — | |
| W18 | OEM-A-2 | FT450-A-A21 | 0.5 | no route | Oxygen (lambda) sensor signal | — | |
| W19 | OEM-A-9 | FT450-A-A26 | 0.5 | no route | Intake air temperature sensor | — | |
| W20 | OEM-A-1 | FT450-A-A22 | 0.5 | no route | Starter signal (term 50) | — | |
| W21 | OEM-A-11 | FT450-A-A23 | 0.5 | no route | Idle/WOT throttle switch | — | |
| W22 | OEM-A-16 | FT450-A-A25 | 0.5 | no route | A/C compressor signal | — |
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 (6)
| Severity | Code | Subject | Message |
|---|---|---|---|
| error | REQUIRED_UNMAPPED | OEM-A-8 | Required OEM function "Hall sender supply (distributor)" (power_in) is not connected to the new ECU. |
| warn | LOAD_UNKNOWN | FT450-A-A6 | FT450-A-A6 "Aux 4 (fuel pump / relays)" drives OEM-A-3 Fuel pump relay control (load 0.2 A) but its current rating is unknown. Check the ECU manual. |
| warn | NET_FAMILY | OEM-A-1 ↔ FT450-A-A22 | OEM-A-1 "Starter signal (term 50)" [digital_in] is wired to FT450-A-A22 "White input 3 (TPS)" [analog_in]. Analog and digital on one net. A switch on an analog input works with a pull-up and a threshold; an analog sensor on a digital input loses its value. |
| warn | NET_FAMILY | OEM-A-11 ↔ FT450-A-A23 | OEM-A-11 "Idle/WOT throttle switch" [digital_in] is wired to FT450-A-A23 "White input 4 (oil pressure)" [analog_in]. Analog and digital on one net. A switch on an analog input works with a pull-up and a threshold; an analog sensor on a digital input loses its value. |
| warn | NET_FAMILY | OEM-A-16 ↔ FT450-A-A25 | OEM-A-16 "A/C compressor signal" [digital_in] is wired to FT450-A-A25 "White input 6 (fuel pressure)" [analog_in]. Analog and digital on one net. A switch on an analog input works with a pull-up and a threshold; an analog sensor on a digital input loses its value. |
| info | UNMAPPED | OEM | 2 optional OEM pins are not mapped: OEM-A-4 Knock sensor signal; OEM-A-7 Knock sensor shield |
Accepted (0)
| Code | Subject | Reason | By |
|---|
Notes
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-A 8: Hall sender supply (distributor): no rule for class sensor_supply_in; wire by hand Not wired: - OEM-A 4: Knock sensor signal: no free knock input on FuelTech FT450 - OEM-A 7: Knock sensor shield: no shield pin on FuelTech FT450
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 | — | — | — |
| 2 | community_copy | a2resource: Digifant II engine controller pinout (VW Golf/Jetta Mk2 1.8 8v) | http://www.a2resource.com/electrical/management/digifant2.html | — | — | — |
| 2 | community_copy | drive2.ru: VW Golf Mk2 PF Digifant II ECU pinout | https://www.drive2.ru/l/9886121 | — | — | — |