Simos 33a Pinout Top Page

Siemens Simos 3.3A (often labeled Simos 33A) is an engine control unit (ECU) primarily used in Volkswagen and Audi vehicles, such as the Audi A3 1.6L (engine codes AEH, AKL). ECU Overview and Key Features Application : Management system for 4-cylinder petrol engines. Connector Type : 80-pin multi-plug connector. Service Tasks : Common procedures include reading pin codes for (immobilizer bypass) or cloning using bench tools like the Simos 3.3A Pinout Summary

Based on the standard 80-pin wiring diagram for the Simos 3.3A (1.6L engine), the following are the primary power, ground, and communication pins: Pin Number(s) Ground (Main) Positive (+) Battery (Terminal 30) Ignition Switch (Terminal 15) K-Line (Diagnostics) Fuel Pump Relay Control Engine Speed Sensor (G28) Injector and Sensor Wiring Simos series Current Flow Diagram

details the following specific connections for the fuel system: : Controlled via pins that trigger based on firing order. Hall Sender (G40) : Typically connected to pin 62. Coolant Temperature Sender (G62) : Provides input for engine management adjustments. Bench Connection Guide

For "top" or bench-mode access (for flashing/reading), professional tools often use the following standard setup: Power (+12V) : Pin 18 (Permanent) and Pin 3/37 (Switched). Ground (-) : Pins 1 and 2. Communication

: K-Line at Pin 43 is the primary method for Simos 3.3A/3.4A ECUs.

Simos Control Unit Wiring Diagram | PDF | Fuel Injection - Scribd simos 33a pinout top

Combines fuel injection, ignition timing, and electronic throttle control (EPC). Communication:

interface for diagnostics via tools like VAG 1551 or VAS 5051. Components:

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

For a detailed visual of the "top" view or specific PCB soldering pads, technicians often refer to Simos ECU Connection Guides on Scribd Skoda Fabia Simos 3 Pinout Guide troubleshoot a specific sensor issue?

Simos 7.1 Pinout and Installation Guide | PDF | Fuel Injection Siemens Simos 3

Step 1: Locate Power and Ground (KL30 & KL31)

• Look for thick copper traces leading to the connector pins. These are always power or ground.
• Use a multimeter in continuity mode. Touch one probe to a large ground plane (the exposed copper on the edge of the PCB). Probe the connector pins on the top side – the pin that beeps is KL31 (Ground).
• KL30 (Battery+) will have a trace leading directly to a large electrolytic capacitor (usually 4700µF or similar). Find the capacitor's positive leg; trace it back to the connector pin.

Step 2: Find CAN Bus Pins

• On the top side, locate the TLE7250G or TJA1040 CAN transceiver chip (a small 8-pin SOIC IC).
• Pin 1 of that chip is usually TXD, Pin 4 is RXD, but Pin 7 is CAN_H and Pin 6 is CAN_L. Follow the tiny PCB tracks from Pin 7 and Pin 6 back to the main connector. Those are your CAN pins.

Step 3: Identify KL15 (Ignition Wake-Up)

• KL15 is not a high-current pin. It usually connects to a voltage divider (two resistors in series) that then feeds a microcontroller pin.
• On the top view, look for a small 10k-100k ohm resistor near the main connector. One side will be connected to a pin (KL15), the other to the MCU. Probe for 12V only when ignition is ON.

1. Simos 33A Connector Overview

The Simos 33A ECU uses a 154-pin Tyco / AMP connector (often referred to as the "Tyco 154-pin header"). The connector is physically large and rectangular, with pins arranged in several rows. When the ECU is mounted in the car, the connector faces downward. However, when you remove the ECU and flip it over for bench work, the top side refers to the side of the connector where the plastic housing mates with the ECU’s circuit board.

From the top perspective (looking directly at the open connector face with the locking lever oriented correctly), pins are organized into:

• 4 rows (A, B, C, D) – Pin 1 in row A starts near the locking latch.
• Some versions also include an additional row for high-current power stages.
• Each pin is labeled either on the circuit board or on the connector housing.

⚠️ Important: There are multiple hardware revisions of the Simos 33A (e.g., 33A.6, 33A.7, 33A.12). While pin assignments are largely consistent, always verify with wiring diagrams specific to your vehicle model.

1. Overview: The SIMOS 33A Hardware Layout

The SIMOS 33A is a 64-pin ECU. It uses three separate connectors (often labeled A, B, and C). However, the common terminology for identifying "top" refers to the main engine harness connector (usually Connector A or T80) or the physical top row of the 64-pin arrangement.

On most SIMOS 33A ECUs:

• Top Connector (T80 / Connector A) – Main engine control (sensors, actuators, power)
• Middle Connector (Connector B) – Additional inputs (A/C, clutch, brake, speed)
• Bottom Connector (Connector C) – Diagnostics, CAN bus, immobilizer (via K-Line)

Important: Pin numbers, colors, and functions can vary slightly depending on:

• Vehicle model (Golf vs. Polo vs. A2)
• Engine code (e.g., AUD, AEX, APE, AZD, BCA)
• Regional emissions (EU2 vs EU3 vs EU4)
• Manual vs. automatic transmission

This write-up provides the most common top connector pinout (60-pin or 64-pin depending on production year), used in majority of SIMOS 33A ECUs. Always verify with your specific wiring diagram.

3. Power & Ground Distribution (Top-Side Critical Pins)

From the top perspective, power management is the most frequent source of confusion. The Simos 33A uses multiple battery and ground pins to handle high injector and coil currents.

Overview of the SIMOS 33A

The SIMOS 33A typically comes in a compact, sealed plastic housing. It is a flash-based ECU (TC1796 processor), making it a popular target for tuning via tools like Kess, Ktag, or MPPS.

Physically, the ECU is divided into distinct connector sections (plugs), usually referred to as Plug A, Plug B, Plug C, and Plug D. Step 1: Locate Power and Ground (KL30 & KL31)