Fangrui Product Details 1. Through The Continuous Automobile Battery 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, Its Normal The Green Led Will Light. 5. Fine Workmanship And Good Performance. 6. Easy To Operate. 7. Convenient To Carry. 8. Durable In Use. 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 Contact