Simos 33a Pinout Top May 2026

Assuming you mean the Siemens SIMOS 33A engine control unit (ECU) connector pinout — common in some Volkswagen/Audi/Seat/Skoda vehicles — here’s a compact reference for the connector "Top" (often the 55-pin / 67-pin SIMOS variants vary; this follows the common 55-pin SIMOS 33A layout). Use this only as a guide — verify against vehicle-specific documentation before wiring.

If you are working on a specific engine code or vehicle, I can refine the pinout further (e.g., AZD, AEX, BCA differences). Do you have a specific ECU part number or VIN range in mind? simos 33a pinout top

Key Pinout Table (Top View – most useful for probing from top):

| Pin | Function | Signal Type | Notes | |-----|----------|-------------|-------| | 1 | Ignition coil output (cyl 1) | Output | Low side driver | | 2 | Injector output (cyl 1) | Output | Saturation driver | | 3 | Injector output (cyl 2) | Output | | | 4 | Injector output (cyl 3) | Output | | | 5 | Injector output (cyl 4) | Output | | | 6 | Fuel pump relay control | Output | Grounds relay coil | | 7 | Lambda probe heater (front) | Output | Ground side | | 8 | Throttle valve position sensor (TPS) ground | Sensor Ground | | | 9 | TPS signal (wiper) | Input | 0.5-4.5V | | 10 | TPS 5V supply | Output | +5V reference | | 11 | Intake air temp (IAT) signal | Input | | | 12 | Coolant temp (ECT) signal | Input | | | 13 | MAP sensor signal | Input | Manifold absolute pressure | | 14 | MAP sensor 5V supply | Output | | | 15 | MAP sensor ground | Sensor Ground | | | 16 | Ignition coil output (cyl 2) | Output | | | 17 | Ignition coil output (cyl 3) | Output | | | 18 | Ignition coil output (cyl 4) | Output | | | 19 | +12V main relay output | Power | To sensors/actuators | | 20 | +12V permanent (battery) | Power | Direct from battery | | 21 | +12V from main relay | Power | ECU main supply | | 22 | Ground (power) | Ground | High current | | 23 | Ground (power) | Ground | High current | | 24 | Ground (sensor) | Sensor Ground | | | 25 | CAN High (if equipped) | Comm | Drivetrain CAN | | 26 | CAN Low (if equipped) | Comm | | | 27 | Knock sensor 1 signal | Input | | | 28 | Knock sensor 2 signal | Input | | | 29 | Crank position sensor (CKP) signal | Input | 60-2 wheel | | 30 | CKP sensor ground | Shield/Ground | | | 31 | Cam position sensor (CMP) signal | Input | Hall effect | | 32 | CMP sensor supply | Output | +5V or +12V | | 33 | CMP ground | Ground | | | 34 | Lambda probe signal (front) | Input | 0-1V narrowband | | 35 | Lambda probe ground (front) | Ground | | | 36 | Vehicle speed sensor (VSS) | Input | | | 37 | Brake light switch signal | Input | | | 38 | Clutch switch signal | Input | | | 39 | A/C request signal | Input | | | 40 | A/C compressor enable | Output | | | 41 | EPC warning lamp | Output | | | 42 | Check engine lamp (MIL) | Output | | | 43 | Diagnostic K-line (ISO 9141) | Comm | | | 44 | Idle air control (IAC) - close | Output | Stepper motor coil | | 45 | Idle air control (IAC) - open | Output | Stepper motor coil | | 46 | EVAP purge valve control | Output | | | 47 | Secondary air injection (SAI) relay | Output | | | 48 | Oxygen sensor heater (rear) | Output | If present | | 49 | Idle air control (IAC) - coil B | Output | | | 50 | Idle air control (IAC) - coil A | Output | | | 51 | Not used | - | | | 52 | Not used | - | | | 53 | +12V switched (e.g., from alternator) | Input | Load signal | | 54 | Power ground | Ground | | | 55 | Power ground | Ground | | | 56 | Sensor ground | Ground | | | 57 | Ignition switch input (Terminal 15) | Input | +12V when key ON | | 58 | Start signal (Terminal 50) | Input | +12V during cranking | | 59 | Engine speed output (to tachometer) | Output | Low side driver | | 60 | +12V backup (for adaptive memory) | Power | Permanent | Assuming you mean the Siemens SIMOS 33A engine

Note: Pin locations can vary slightly between hardware revisions. Always look for the pin numbers stamped on the ECU plastic housing next to the connector slots. Do you have a specific ECU part number or VIN range in mind