Simos 3.3a Pinout Site

The ECU uses two main connectors: (Often labeled connector A) and T105 (Connector B). Below is the full engineering breakdown.

For bench operations—such as reading or writing the internal or flash memory—the following essential pin connections are used to establish communication with programming tools like KESS, PCMtuner, or OBDSTAR . Signal Type ECU Pin Number Description +12V (Power) Permanent and switched power supply GND (Ground) Main electrical ground connection K-Line Primary diagnostic and programming communication line Key Applications and Procedures simos 3.3a pinout

The SIMOS 3.3A is legendary but has quirks: The ECU uses two main connectors: (Often labeled

In the realm of European automotive diagnostics and ECU tuning, few control units are as ubiquitous or as complex as the Simos 3.3a. Found under the hood of millions of VAG (Volkswagen Audi Group) vehicles—most notably the 1.8T and early 2.0 FSI engines—this ECU (Engine Control Unit) represents a pivotal transition in automotive technology. It bridges the gap between the simpler OBD1 era and the highly encrypted, CAN-bus-heavy modern era. Signal Type ECU Pin Number Description +12V (Power)