Simos | 33a Pinout Top ((full))

The Simos 33A uses a highly integrated system layout designed to process inputs from multi-point injectors, knock sensors, and electronic throttle bodies (EPC) simultaneously. Unlike older standalone systems, this module handles ignition, fueling, and exhaust management via a dense multi-connector block configuration. The Top-Perspective Pin Mapping

Interfaces with the G28 Engine Speed Sender, Hall Sender (G40), and multiple Coolant Temperature Senders (G2, G62).

The SIMOS 33A is a robust ECU, but its small form factor and densely packed pins require careful attention to detail. Whether you are diagnosing a sensor fault or setting up a bench harness, having the correct pinout map saves hours of frustration.

Save an untouched backup of the original bin file before modifying any timing, fuel, or immobiliser parameters. simos 33a pinout top

| Signal Type | Example Pins | |---------------------|-------------------| | Power (12V) | 1, 3 | | Ground | 2, 7, 18, 30 | | 5V analog input | 6, 20, 29 | | Frequency input | 8, 9, 32 | | Low-side output | 11–13, 14, 16, 17, 23, 24, 31 | | Stepper motor | 25, 26, 27, 28 | | Shield/shield ground| 10, 22 |

For detailed wiring diagrams including sensor colors and relay locations, the VW ElsaWin software

Simos 33a Pinout Top: A Comprehensive Guide to Siemens 121-Pin ECU Wiring The Simos 33A uses a highly integrated system

| 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 |

Operating the throttle valve actuator (V60) and potentiometers (G69/G88). Bench Reading and Diagnostics

The view is an essential map for anyone diagnosing, tuning, or repairing modern VAG ECUs. By understanding the physical layout—identifying power headers, CAN transceivers, and test points—you can confidently probe the ECU on your bench or in the vehicle. The SIMOS 33A is a robust ECU, but

On the top side, you can also use TP24 (CAN_H) and TP23 (CAN_L) as solder points for bench harnesses.

: Look closely at the plastic mold of the ECU connector headers. Pin numbers are stamped in micro-print on the top corner margins of the housing.

Simos 7.1 Pinout and Installation Guide | PDF | Fuel Injection

These are the most important pins for powering the ECU on a bench for reading/writing. Pin 1 (GND): Ground (Signal/Power Ground) Pin 2 (GND): Ground Pin 3 (GND): Ground Pin 62 (KL30): Permanent +12V (Battery) Pin 87 (KL15): Switched +12V (Ignition) Pin 60 (K-Line): Diagnostic communication line. Engine Management & Sensors Pin 13 (G28): Engine Speed Sender (Crankshaft Sensor) Pin 53 (G62): Coolant Temperature Sensor Pin 70 (G70): Air Mass Meter Signal Pin 71 (G185): Accelerator Pedal Position Sensor Pin 75 (G71): Intake Manifold Pressure Sensor Pin 79 (G61): Knock Sensor Pin 110 (G186): Throttle Valve Drive Actuators & Fuel Pin 65 (N30): Injector Cylinder 1 Pin 66 (N31): Injector Cylinder 2 Pin 67 (N32): Injector Cylinder 3 Pin 68 (N33): Injector Cylinder 4 Pin 91 (N152): Ignition Coil Module Pin 103 (N80): Fuel Tank Evap Purge Valve 3. Bench Flashing/Pinning Guide (Top Connector)