How Do I Test a Relay with a Multimeter?

QuestionsCategory: Ask An ExpertHow Do I Test a Relay with a Multimeter?
Evelyn Miller asked 5 months ago
I came across a relay in my car and I'm not entirely sure how to test it using a multimeter. I've seen various methods online, but I'm looking for a straightforward and effective way to confirm if the relay is working properly. Can you provide a step-by-step guide on how to test a car relay with a multimeter?
1 Answers
Zack Norman Staff answered 5 months ago
Hey there, Evelyn! Testing a car relay with a multimeter is a great skill to learn to help you diagnose and troubleshoot future electrical issues, and learning how it's done is actually pretty easy. Here's a step-by-step process:
  1. Identify the Relay Pins: First, locate the small control pins and the larger power pins on the relay.
  2. Testing the Control Circuit:
    • Set your multimeter to measure DC voltage.
    • Apply 12 volts to the small pins (you can use a 12V battery or equivalent source).
    • If the relay clicks, the control side is functioning.
  3. Testing the Power Circuit:
    • Now, set your multimeter to continuity mode.
    • With 12 volts still applied to the small pins (thus the relay is active), check for continuity across the large pins.
    • If there is continuity, the power side is working.
  4. Resistance Check:
    • You can also check the resistance across the coil winding (small pins). This tells you if the coil is intact.
  5. Visual Inspection (Optional):
    • Some relays allow you to pop off the cover without damage. This lets you visually inspect the internal mechanism.
Remember, a good relay will show continuity across the large pins when activated and no continuity when deactivated. Also, ensure there's no significant resistance through the contacts when they're closed. Please handle electrical components carefully and disconnect the power source when not actively testing! Do let us know how you get on! Zack - Motor Verso Mechanics Team