This page is a highly specialized technical reference for the Bosch Motronic M3.3.1 electronic engine management system.
Main Contents
- Pinout: A complete list detailing the purpose of each contact (pin) on the DME connectors.
- Diagnosing and troubleshooting complex M3 wiring.
- Wiring Diagram: Illustrates how these DME contacts are connected to the complex engine peripherals.
- Testing signals for the ITB, knock sensors, VANOS, and other specialized S50 components.
- Repairing or replacing the DME itself, as well as performing tuning or swaps.
The M3.3.1 system was installed exclusively on European high-performance E36 M3 models with S50B30 and S50B32 engines. This information is critical for working with engines equipped with individual throttle bodies (ITBs).
BMW Bosch M3.3.1 Pinout (M50 Engine)
BMW M3 (E36) M50 Engine M3.3.1 Wiring Diagram
BMW Bosch M3.3.1 Pinout (M50 Engine)
BMW 5 (E34) M50 Engine M3.3.1 Wiring Diagram (1995)
- E = Input
- A = Output
- M = Ground
Bosch Motronic M3.3.1 Pinout. M3 E36 (M50)
| Pin | Type | Description/Function | Connection |
| 1 | A | Fuel pump relay control | Fuel pump relay, terminal 85 |
| 2 | A | Idle speed control valve - close winding control | Idle speed control valve |
| 3 | A | Cyl. 5 fuel injection valve control | Cyl. 5 fuel injection valve |
| 4 | A | Cyl. 6 fuel injection valve control | Cyl. 6 fuel injection valve |
| 5 | A | Cyl. 4 fuel injection valve control | Cyl. 4 fuel injection valve |
| 6 | M | Ground, fuel injection valve output stages | Ground point |
| 7 | A | Camshaft actuator control | Camshaft actuator |
| 8 | A | "Check engine" indicator control | Instrument cluster |
| 9 | Not used | ||
| 10 | Not used | ||
| 11 | A | Throttle valve position | Transmission control module (EGS) |
| 12 | Not used | ||
| 13 | E | Oxygen sensor signal | Heated oxygen sensor |
| 14 | A | Hot wire air mass meter | Hot wire air mass meter |
| 15 | M | Ground | Ground point |
| 16 | E | Crankshaft position/RPM sensor signal (+) | Crankshaft position/RPM sensor |
| 17 | E | Camshaft position sensor | Hall effect camshaft sensor |
| 18 | Not used | ||
| 19 | Not used | ||
| 20 | Not used | ||
| 21 | Not used | ||
| 22 | Not used | ||
| 23 | A | Cyl. 4 ignition coil control | Cyl. 4 ignition coil |
| 24 | A | Cyl. 6 ignition coil control | Cyl. 6 ignition coil |
| 25 | A | Cyl. 5 ignition coil control | Cyl. 5 ignition coil |
| 26 | E | Battery voltage | B+ junction point |
| 27 | A | Engine control module relay control | Engine control module relay, terminal 85 |
| 28 | M | Ground for electronics and shielding of sensors | Ground point |
| 29 | A | Idle speed control valve - opening winding control | Idle speed control valve |
| Pin | Type | Description/Function | Connection |
| 30 | Not used | ||
| 31 | A | Cyl. 3 fuel injection valve control | Cyl. 3 fuel injection valve |
| 32 | A | Cyl. 2 fuel injection valve control | Cyl. 2 fuel injection valve |
| 33 | A | Cyl. 1 fuel injection valve control | Cyl. 1 fuel injection valve |
| 34 | M | Ground remaining output stages (except for ignition and fuel injection valves) | Ground point |
| 35 | Not used | ||
| 36 | A | Evaporative emission valve control | Evaporative emission valve |
| 37 | Not used | ||
| 38 | A | Oxygen sensor heater control | Oxygen sensor relay, terminal 85 |
| 39 | Not used | ||
| 40 | M | Oxygen sensor signal ground | Heated oxygen sensor |
| 41 | E | Hot wire air mass meter | Hot wire air mass meter |
| 42 | E | Vehicle speed signal | Instrument cluster |
| 43 | E | Crankshaft position/RPM sensor signal (–) | Crankshaft position/RPM sensor |
| 44 | M | Ground for sensors | Engine intake air temperature sensor, engine coolant temperature sensor, and throttle position sensor |
| 45 | M | Ground for shield | Shield |
| 46 | A | TI measurement signal (fuel consumption) | Instrument cluster |
| 47 | A | Crankshaft RPM speed signal TD | Instrument cluster |
| 48 | A | A/C compressor control | Compressor control relay, terminal 85 |
| 49 | Not used | ||
| 50 | A | Cyl. 1 ignition coil control | Cyl. 1 ignition coil |
| 51 | A | Cyl. 2 ignition coil control | Cyl. 2 ignition coil |
| 52 | A | Cyl. 3 ignition coil control | Cyl. 3 ignition coil |
| 53 | Not used | ||
| 54 | E | Battery voltage from engine control module relay | Engine control module relay, terminal 87a |
| 55 | M | Ground, ignition | Ground point |
| 56 | E | Ignition switch, terminal 15 | Ignition switch |
| 57 | E | Ignition timing intervention | Transmission control module (EGS) |
| 58 | Not used | ||
| 59 | A | 5V component supply | Throttle position sensor |
| Pin | Type | Description/Function | Connection |
| 60 | E | Programming voltage | Data link connector |
| 61 | Not used | ||
| 62 | E | EML-signal | ABS/ASC control module |
| 63 | Not used | ||
| 64 | E | A/C switch | Integrated climate regulation control module |
| 65 | E | A/C pressure signal | Pressure switch |
| 66 | E | Drive-away protection signal (code) | Electronic immobilizer control module (EWS II) |
| 67 | Not used | ||
| 68 | Not used | ||
| 69 | E | Cyl. 4-6 knock sensor | Cyl. 4-6 knock sensor |
| 70 | E | Cyl. 1-3 knock sensor | Cyl. 1-3 knock sensor |
| 71 | M | Ground for knock sensors and shields | Cyl. 1-3 knock sensor, cyl. 4-6 knock sensor, and shields |
| 72 | Not used | ||
| 73 | E | Throttle position | Throttle position sensor |
| 74 | Not used | ||
| 75 | Not used | ||
| 76 | Not used | ||
| 77 | E | Engine intake air temperature | Engine intake air temperature sensor |
| 78 | E | Engine coolant temperature | Engine coolant temperature sensor |
| 79 | Not used | ||
| 80 | Not used | ||
| 81 | E | Drive range P/N | Automatic transmission range switch |
| 82 | E | Throttle flap position | ABS/ASC control module |
| 83 | A | Ignition cut-off signal | ABS/ASC control module |
| 84 | Not used | ||
| 85 | Not used | ||
| 86 | Not used | ||
| 87 | E | RxD diagnosis data line | Data link connector |
| 88 | E/A | TxD diagnosis data line | Data link connector |
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E = Input
-
A = Output
-
M = Ground
-
E/A = Input/Output