The following pinout information is a for the SIMOS 33A ECU. Pin functions and assignments can vary between different vehicle models, engine codes, and model years . Always consult the official factory wiring diagram for your specific vehicle before performing any work.
: Often required to "wake up" the unit for reading/writing. Specific Wiring Details (Reference)
L-Line (Initialization, used on older diagnostic tools) Critical Sensor Inputs
When tracing wire harness schematics or performing an engine swap (such as retrofitting a BFQ motor into an older chassis), use this targeted breakdown of the top essential sensor lines: Target Component ECU Pin Number Wire Function / Type Pin 82 & Pin 90 Inductive Crankshaft Position Input Camshaft Position Sensor (G40) Hall Effect Signal Input Mass Air Flow Meter (G70) Load Signal Input Throttle Actuator Potentiometer (G88) Throttle Position Feedback Coolant Temperature Sensor (G62) Resistance Engine Temperature Signal Fuel Injectors (Cylinders 1–4) Pins 86, 87, 88, 89 Switched Ground Actuator Outputs 💾 Reading the ECU: EEPROM and Boot Mode simos 33a pinout top
If you are working on a specific diagnostic or tuning task, let me know:
Depending on what firmware operation you intend to perform on the internal C167 chip, you will use one of two modes: Connection Mode Method Requirements Best Used For External pin wiring only; no case removal.
Are you planning to use a specific tool like or K-Tag for this connection? The following pinout information is a for the SIMOS 33A ECU
If your bench tool fails mid-read, navigate to your interface's software options menu and manually select or a lower baud rate. The Siemens microcontrollers in the Simos 3.3A Go to product viewer dialog for this item.
Resolving cluster pairing issues on older vehicles.
Establishing bench communication requires precision to prevent internal component damage from voltage spikes or shorts. Follow these operational protocols: : Often required to "wake up" the unit for reading/writing
While some Simos versions support OBD reading, users often report that Simos 3.3 may not work via OBD for full read/write operations, necessitating a full system pinout on the bench.
The Siemens Simos 3.3A uses a standard dual-connector assembly split into a larger wiring block and a smaller wiring block. To bring the unit to life safely on an external power supply, you must supply 12V stable power, clean ground paths, and establish standard K-Line communication protocols. Connection Type ECU Pin Assignment Recommended Wire Color Main Battery Line (Terminal 30) Pin 3 Switched Power (+12V) Ignition Signal (Terminal 15) Pin 62 Orange / Yellow Ground (GND) Chassis Earth Return (Terminal 31) Pin 1 (or Pin 2) Data Communication K-Line Diagnosis Line Pin 43 Blue / Green