The **G8H-1C4T-R** is a specific type of automotive power relay manufactured by **Omron**. It is designed for high-current switching applications within vehicles. --- ## 1. Technical Specifications Below are the primary electrical and physical characteristics of the G8H-1C4T-R: | Feature | Specification | | :--- | :--- | | **Relay Type** | Automotive Power Relay | | **Contact Form** | SPDT (1 Form C) | | **Coil Voltage** | 12 VDC | | **Max Switching Current** | 20A to 35A (Application dependent) | | **Terminal Style** | Plug-in / ISO Terminals | | **Internal Resistor** | Yes (Suppression resistor across the coil) | | **Operating Temp** | -40°C to +125°C | --- ## 2. Key Component Features ### A. Contact Configuration (SPDT) The **1C** in the part number indicates a **Single Pole Double Throw** configuration. This means the relay has one common terminal that switches between a "Normally Closed" (NC) contact and a "Normally Open" (NO) contact. ### B. Built-in Resistor (The "-R" Suffix) The **-R** indicates that the relay includes an internal **suppression resistor** connected in parallel with the coil. * **Function:** When the relay coil is de-energized, the magnetic field collapses, creating a high-voltage spike (back-EMF). * **Benefit:** The resistor dissipates this energy, protecting sensitive automotive electronics and control modules (like the ECU) from voltage surges. ### C. Environmental Durability The **"T"** designation often refers to high-heat resistance or specific sealing, allowing the part to function reliably in the engine compartment where temperatures fluctuate significantly. --- ## 3. Pinout Diagram (Standard ISO) Most G8H series relays follow the standard ISO 280 footprint: | Pin Number | Function | | :--- | :--- | | **85** | Coil Ground | | **86** | Coil Power (Trigger) | | **30** | Common Contact (Input) | | **87a** | Normally Closed (NC) Output | | **87** | Normally Open (NO) Output | --- ## 4. Common Applications Due to its robust current handling and compact size, this relay is frequently used for: * Fuel Pump control * Air Conditioning (A/C) compressor clutches * Blower motors * Engine cooling fans * Horn circuits ---