The importance of relay tester Most car lights, wipers, starters, air conditioners, electric seats, electric doors and windows, anti-lock brakes, and audio all use relays. Automotive relays suffer from vibration, high temperature, low temperature, humidity, etc., which will reduce their life. But once the relay fails, it will immediately cause the paralysis of the system components, and even cause the entire vehicle to be unusable. Therefore, it is very important to regularly check the relays inside the car. Tester will check for proper functioning of the relay contacts by connecting the car battery (11V--15V) to the relay coil. Features: Automotive relays test tool.1.Through the continuous automobile battery (11V-15V) to the relay coil, the detector can properly check the relay contact function.2. The tester observes contact data, closure time, relay inertia at each test stage, etc.3. Test to properly control the opening and closing of the relay.4. If the relay is abnormal the red LED will light, it's normal the green LED will light.5. Fine workmanship and good performance.6. Easy to operate.7. Convenient to carry.8. Durable in use. Material: Plastic & MetalColor: Black & RedVoltage: 12VSize: approx. 110 * 60 * 28mmproduct name:automotive relay tester1 x 12V Relay Tester Five High Advantages: 1.Safety and environmental protection2.Good durability3.Cost-effective4.Strong temperature resistance5.Lightweight and generous Note: Car battery must be 12V battery, the voltage must be between 11-15V. The coil resistance is preferably at least 20 ohms. How to use the tool? The Steps are as Follows1. Connect the power leads to the car battery --black alligator clip to negative terminal, red alligator clip to positive terminal.2. Tester is powered up when the LED illuminates in RED.3. Check the relay before plugging into the tester. If it's a 4 pin relay,select"4 pin" on the tester.If it's a 5 pin relay, select"5 pin"on the tester.4. Plug in the relay into one of the three receptacles.5. Press the "TEST" button.6. Tester will check the pin configuration of the unknown relay. Tester will light the RED LED if the unkonwn relay is not the same to the most of common automotive relaysor the pin of the unknown relay is destroyed.7.Tester will open and close the relay 10 times for testing the time to contacts closure and opening if the pin configuration of the relay is right. Tester will light the RED LED immediately if the time is overtime.8. Tester will check the consistency of the relay after testing the time to contacts closure and opening ten times. Tester will light the GREEN LED if the test passed, if not light the RED LED.9. Disconnect power leads from the car battery and remove relay from the tester.