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Pinout Top | Simos 33a

              ┌─────────────────────────────┐
              │                             │
      Row A   │ 01 02 03 ... ... ... 14 15   │ (Top/Component side)
      Row B   │ 16 17 18 ... ... ... 29 30   │
      Row C   │ 31 32 33 ... ... ... 44 45   │
      Row D   │ 46 47 48 ... ... ... 59 60   │ (Bottom/Solder side)
              │                             │
              └─────────────────────────────┘

The SIMOS 33A (often labeled with part numbers like 03C 906 016) is a gasoline engine control unit manufactured by Siemens/VDO. It is widely used in vehicles such as the VW Golf Mk5, Seat Leon, and Audi A3.

Unlike older ECUs where the printed circuit board (PCB) was the primary focus, the SIMOS 33A moved toward a hybrid construction. This makes internal repair more difficult, but external pinout knowledge is essential for diagnostics and "bench" programming.

For repair or pinout tracing, group logically:

A. Power & Ground

B. Ignition System

C. Fuel System

D. Sensors – Engine Management

E. Idle Control

F. Emissions Control

When you remove the lid of a Simos 33A ECU, the top side reveals the following key landmarks: simos 33a pinout top

While diagnostics are usually through the lower connector (K-line), the top connector provides:

Do not apply +12V to any sensor signal pins (e.g., pin 6 TPS) – they are 0-5V only.