An ignition switch (also called a master switch or total electric door) is the central gate controlling the entire vehicle's electrical system—it uses a key rotation to open or close the main circuit of the ignition coil and other electrical circuits . A typical heavy-equipment ignition switch features a four-position structure—LOCK (lock) / OFF (off) / ON (power on) / START (start), with some machines adding an ACC (accessory) position . Internally it integrates a cylinder lock, contact plates, and a relay, connecting to the battery, starter motor, and ECU; the correct operating sequence is OFF → ON → START, after which the key springs back to ON automatically .
This 803604576 ignition switch is suitable for power start/stop control across excavators, wheel loaders, cranes, and similar heavy machinery, with waterproof, dustproof, and anti-vibration properties for stable operation in harsh field conditions . Routine maintenance should check the smoothness of the cylinder, oxidation or corrosion on the contacts, and the reliability of wire connections to prevent start failures due to poor contact .
⚠️ Verification Notice: No official datasheet for 803604576 was found in public channels. Before ordering, please confirm the following three items—
① The original part number on the equipment nameplate or electrical schematic;
② The ignition switch position structure (3-position / 4-position / with ACC);
③ The number of terminals and wiring sequence (commonly 3-wire / 4-wire).
Different machine models may have different position definitions and wiring layouts—do not replace across models based solely on visual similarity.
