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Me7.4.5 Pinout Fixed -

ME7.4.5 Pinout — Compact Handbook

This handbook summarizes the ME7.4.5 engine control unit (ECU) pinout, typical signal roles, wiring notes, diagnostic tips, and safe-handling procedures. It’s written for experienced technicians and advanced hobbyists working on vehicles that use Bosch ME7.4.5 ECUs (commonly found in many late-1990s to 2000s gasoline-powered European cars). Treat this as a reference supplement to factory service manuals — verify vehicle-specific diagrams before wiring or testing.

  • Crank (A42)
  • MAP (A55)
  • TPS (A62)
  • Coolant temp (A70)
  • Lambda (A38) – or disable via tune.

The following sections provide a more detailed overview of the ME7.4.5 pinout:

🔌 T121 Pinout (Engine Control Harness – Most critical for diagnostics & modification)

| Pin | Signal | Description | |------|----------------|------------------------------| | 1 | Power | Permanent +12V (ECU main) | | 2 | Ground | Power ground | | 3 | Ignition output | Ignition coil cylinder 1 | | 4 | Ignition output | Ignition coil cylinder 2 | | 5 | Ignition output | Ignition coil cylinder 3 | | 6 | Ignition output | Ignition coil cylinder 4 | | 7 | Injector output | Injector cylinder 1 | | 8 | Injector output | Injector cylinder 2 | | 9 | Injector output | Injector cylinder 3 | | 10 | Injector output | Injector cylinder 4 | | 11 | O2 sensor heater | Pre-cat O2 heater (bank1) | | 12 | O2 sensor heater | Post-cat O2 heater | | 13 | MAF signal | Mass air flow sensor signal | | 14 | MAF ground | Sensor ground | | 15 | Sensor +5V | Reference voltage | | 16 | Throttle position | TPS signal | | 17 | MAP sensor | Manifold absolute pressure | | 18 | IAT sensor | Intake air temp | | 19 | ECT sensor | Engine coolant temp | | 20 | Knock sensor 1 | Signal | | 21 | Knock sensor 2 | Signal | | 22 | Cam position | Hall sensor signal | | 23 | Engine speed | Crank sensor signal | | 24 | CAN low | Diagnostic CAN bus | | 25 | CAN high | Diagnostic CAN bus | | 26 | K-line | Diagnostic K-line (ISO 9141) | | 27 | N75 valve | Boost control solenoid | | 28 | EVAP purge | Purge valve control | | 29 | SA output | Secondary air injection relay | | 30 | Fuel pump relay | Control signal | | 31 | Main relay | Power supply relay control | | 32 | Ground | Sensor ground | | 33 | +5V | Sensor supply | | 34 | TPS ground | Throttle position ground | me7.4.5 pinout

Auxiliary Inputs/Outputs

Final Checklist Before Starting Your Engine Swap or Repair

✅ Battery disconnected
✅ ME7.4.5 pinout printed and verified with vehicle year
✅ All grounds (pins 1, 3, 70, 71) secured to clean metal
✅ +12V permanent (pins 4, 72, 73) and switched (5, 69) present
✅ CAN bus (6,7) resistance approximately 60 ohms between pins
✅ Fuel pump relay control (19) connected correctly
✅ No bent pins inside the T121 housing Crank (A42) MAP (A55) TPS (A62) Coolant temp

Motorised Throttle Management: Eliminates the physical accelerator cable, using a "driver's wish" voltage from the pedal sensor to adjust engine torque.

If the ECU is unresponsive ("bricked"), you must put it into to flash the internal memory directly The following sections provide a more detailed overview

For detailed schematics of specific vehicle models, such as the Citroën C4, technical manuals provide full wiring diagrams that map these ECU pins to their corresponding engine sensors.