Bosch Motronic Ecu Pinout 'link' May 2026

The pinout features of Bosch Motronic Engine Control Units (ECUs) vary significantly by generation, typically defined by the number of pins on their main connector—ranging from early 35-pin versions to more complex 88-pin configurations. These pinouts function as a reference map identifying terminals for battery power, grounds, sensor inputs (e.g., oxygen, throttle position), and actuator outputs (e.g., injectors, ignition coils). Common Bosch Motronic Generations Key Pinout Features Motronic 1.0 35 Pins

• Hall, VR (variable reluctance), or optical inputs. Critical for timing; often labeled CKP/CMP (crank/cam position).

• Locate the Bosch ECU part number (sticker on housing) and vehicle VIN/application.
• Consult the vehicle’s OEM wiring manual or Haynes/Chilton service manuals.
• Bosch service literature and aftermarket ECU wiring guides (specialist forums and technical PDFs) often publish pinouts per part number — cross-check multiple sources.
• For reprogramming/tuning use dedicated ECU bench adapters and tuners that include pinout templates.

| Pin | Function | Notes | |-----|-----------------------------------------|------------------------------| | 1 | Injector cylinder 4 | Low side drive | | 2 | Injector cylinder 3 | Low side drive | | 3 | Injector cylinder 2 | Low side drive | | 4 | Injector cylinder 1 | Low side drive | | 5 | Fuel pump relay control | 12V output to relay coil | | 6 | Main relay control / ignition output | Often terminal 87 relay | | 7 | Ground (power) | Chassis/engine ground | | 8 | Ground (power) | Chassis/engine ground | | 9 | +12V battery (continuous) | Fused (ECU keep-alive) | | 10 | +12V ignition switch | Power when key ON | | 11 | Check Engine Light / MIL | Low side to lamp | | 12 | Idle Air Control valve (one coil) | To IAC valve | | 13 | Idle Air Control valve (other coil) | To IAC valve | | 14 | Canister purge valve | EVAP control | | 15 | EGR valve (if present) | Some variants | | 16 | Camshaft position sensor (Hall) signal | 5V square wave | | 17 | Engine speed / crankshaft position (-) | VR sensor negative or sync | | 18 | Engine speed / crankshaft position (+) | VR sensor positive | | 19 | Knock sensor 1 input | From knock sensor (AC) | | 20 | Knock sensor 2 input | On V6/I6 engines | | 21 | Lambda (O2) sensor heater control | Duty cycle to heater | | 22 | Lambda (O2) sensor signal input | 0–1V narrowband | | 23 | Throttle position sensor (TPS) signal | 0.5–4.5V | | 24 | Intake air temperature (IAT) sensor | NTC thermistor | | 25 | Engine coolant temperature (ECT) sensor | NTC thermistor | | 26 | Mass Air Flow (MAF) sensor signal | 0–5V or frequency (hot wire) | | 27 | Ground (sensor return) | Analog sensor ground | | 28 | +5V sensor supply | To TPS, MAP, ECT, IAT | | 29 | Ignition output cylinder 1 & 6 | Logic level to power stage | | 30 | Ignition output cylinder 2 & 5 | Logic level to power stage | | 31 | Ignition output cylinder 3 & 4 | Logic level to power stage | | 32 | A/C compressor request input | From HVAC panel | | 33 | A/C compressor relay control | ECU cuts for load | | 34 | Power steering pressure switch input | Idle-up trigger | | 35 | Neutral / Park switch (auto trans) | Ground when in P/N | | 36 | Starter signal | From ignition start position | | 37 | Vehicle speed sensor (VSS) signal | Reed switch or hall effect | | 38 | Serial data TX (K‑Line) | Diagnostics (ISO 9141) | | 39 | Not used / coding pin | – | | 40 | Ignition switch output (relay trigger) | Sometimes tach output | | 41 | Ground (power) | Same as pin 7/8 | | 42 | +12V (second main relay output) | Optional | | 43 | – | Often empty | | 44 | IAC valve 2nd coil (alternative) | Some ECUs | | 45 | Camshaft adjuster solenoid (VVT) | Variable valve timing | | 46 | Secondary air injection relay | Some emissions systems | | 47 | – | – | | 48 | – | – | | 49 | Diagnostic enable (K‑Line ground) | Sometimes | | 50 | Tachometer output | Engine speed signal (dash) | | 51 | – | – | | 52 | Ground for sensors | Separate from power ground | | 53 | +5V sensor supply (secondary) | Rare | | 54 | Knock sensor shield / return | Ground for knock sensor coax | | 55 | Ignition module / power stage enable | From ECU to ignition amp | bosch motronic ecu pinout

| Pin # | Signal Name | Description | | --- | --- | --- | | 1 | Battery Voltage | Battery voltage supply | | 2 | Ground | Ground connection | | 3 | Crankshaft Position Sensor | Crankshaft position sensor signal | | 4 | Camshaft Position Sensor | Camshaft position sensor signal | | 5 | Throttle Position Sensor | Throttle position sensor signal | | 6 | Coolant Temperature Sensor | Coolant temperature sensor signal | | 7 | Intake Air Temperature Sensor | Intake air temperature sensor signal | | 8 | Oxygen Sensor | Oxygen sensor signal (lambda probe) | | 9 | Fuel Pump Relay | Fuel pump relay control | | 10 | Injector 1 | Injector 1 control | | 11 | Injector 2 | Injector 2 control | | 12 | Injector 3 | Injector 3 control | | 13 | Injector 4 | Injector 4 control | | 14 | Idle Air Control Valve | Idle air control valve control | | 15 | Fuel Injector Pulse | Fuel injector pulse width modulation | | 16 | Spark Plug 1 | Spark plug 1 control | | 17 | Spark Plug 2 | Spark plug 2 control | | 18 | Spark Plug 3 | Spark plug 3 control | | 19 | Spark Plug 4 | Spark plug 4 control | | 20 | Vehicle Speed Sensor | Vehicle speed sensor signal | | 21 | Brake Light Switch | Brake light switch signal | | 22 | Clutch Pedal Switch | Clutch pedal switch signal | | 23 | Gear Selector | Gear selector signal (automatic transmission) | | 24 | A/C Compressor | A/C compressor control | | 25 | Fan Control | Cooling fan control | | 26 | Heated Oxygen Sensor | Heated oxygen sensor control | | 27 | Fuel Level Sensor | Fuel level sensor signal | | 28 | Intake Manifold Pressure Sensor | Intake manifold pressure sensor signal | | 29 | EGR Valve | EGR valve control | | 30 | Canister Purge Valve | Canister purge valve control | | 31 | Idle Mixture Adjustment | Idle mixture adjustment | | 32 | CO Potentiometer | CO potentiometer signal | | 33 | Lambda Correction | Lambda correction signal | | 34 | Diagnostic Connector | Diagnostic connector (K-line) | | 35 | Ground | Ground connection | | 36 | Knock Sensor 1 | Knock sensor 1 signal | | 37 | Knock Sensor 2 | Knock sensor 2 signal | | 38 | Cylinder Head Temperature Sensor | Cylinder head temperature sensor signal | | 39 | Fuel Rail Pressure Sensor | Fuel rail pressure sensor signal | | 40 | Accelerator Pedal Position Sensor | Accelerator pedal position sensor signal | | 41 | Brake Pedal Position Sensor | Brake pedal position sensor signal | | 42 | Clutch Pedal Position Sensor | Clutch pedal position sensor signal | | 43 | Gearbox Computer | Gearbox computer communication | | 44 | Vehicle Check Connector | Vehicle check connector (optional) | | 45 | Service Connector | Service connector (optional) | | 46 | CAN Bus High | CAN bus high signal | | 47 | CAN Bus Low | CAN bus low signal | | 48 | Ground | Ground connection | The pinout features of Bosch Motronic Engine Control

Motronic 1.1 / 1.3 (55-pin): Common in 1980s/90s BMWs (like the E30) and Opels. These typically use a 3-row, 55-pin connector. Pin 1: Ignition coil timing control. Pin 18: Permanent battery power (+12V). Pin 19: Main ECU ground. Pin 37: Switched power from the main relay. Hall, VR (variable reluctance), or optical inputs