：How to Test a Car Relay with Multimeter: A Step-by-Step Guide
Car relays are crucial components in modern vehicles, acting as switches that control high-current circuits with a low-current signal. They are used in various systems, such as headlights, fuel pumps, horn circuits, and cooling fans. Because relays handle electrical power, a malfunctioning relay can lead to system failures or erratic behavior. Testing a car relay with a multimeter is an effective way to diagnose its condition and ensure that your vehicle’s electrical system operates smoothly. Before starting the test, it is important to understand the basic structure of a car relay. Most automotive relays have either four or five pins. In a typical five-pin relay, Pin 85 and Pin 86 are connected to the coil, which energizes the relay. Pin 30 is the common terminal, Pin 87 is the normally open (N/O) terminal, and Pin 87a is the normally closed (N/C) terminal. Understanding the pin configuration is essential for accurate testing.