| 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 |
Understanding Bosch Motronic ECU Pinouts: A Comprehensive Technical Guide bosch motronic ecu pinout
Throttle Body (DBW): Pins for the electronic throttle motor (G186) and the dual potentiometer sensors (G187/G188) are grouped together to ensure signal integrity [3]. With the engine running at idle, back-probe the
Found on ME7 and newer units. These two twisted wires network the ECU with the instrument cluster, ABS module, and transmission controller. 3. Standard Bosch Pinout Examples sharing the or the car's make
To test a , take the MAF as an example. Identify the MAF signal pin and its ground reference. With the engine running at idle, back-probe the connector at the ECU and measure the DC voltage. The exact value will vary, but it should be a stable voltage that rises as you rev the engine.
The Bosch Motronic system was revolutionary because it combined fuel injection control (L-Jetronic) and digital ignition control into a single, unified electronic unit.
If you are currently troubleshooting a vehicle or working on an engine swap, sharing the or the car's make, model, and year will help locate the specific schematic you need. Let me know if you would like me to list the exact pin configurations for a specific Motronic version or if you need the bench-flashing connections for a particular unit. Share public link
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