Learning how to test an automotive relay is crucial for individuals interested in properly maintaining their car. A relay is a small switch that regulates the circuits and currents for car accessories, such as headlights, fuel pumps, and air conditioners. If a relay fails, then these systems fail to perform as expected. Following these easy steps and using only basic equipment, you can test a relay as described in this guide. If you want to know more about the steps, learn more.
What You’ll Need
Before you start, gather the following tools:
- Multimeter: An instrument that determines electrical values such as resistance, voltage, and continuity.
- Test Light: Helpful in verifying whether current is passing through a particular circuit.
- Jumper Wires are short wires with connectors on two terminals that connect circuits and allow the flow of electricity.
- 12-Volt Battery: To supply energy to the relay during testing.
- Owner’s Manual: To find where the relay is and acquaint yourself with its details.
Step 1: Locate the Relay
This is the first step in repairing your car’s relay. Relay transducers can be mounted inside the fuse box, which can be under the bonnet or within the cabin. Your owner’s manual will specify the location in more detail. Once you are sure of the relay’s position, try to remove it very carefully from its place. If you need automotive test equipment, you can go through the site.
Step 2: Inspect the Relay
Fix the relay before beginning the test to make sure it is okay and has not been damaged in any way. Look for indications of burnout, corrosion, or melted plastic, which can be signs of a bad relay. Wipe the relay pins with a cloth to remove any dirt or corrosion that may affect the relay test results.
Step 3: Test the Relay with a Multimeter
Set Up the Multimeter
Switch on your multimeter and adjust it to measure the resistance, moving the decimal place two points to the right if your multimeter has a continuity mode, that is even more ideal for this test.
Identify the Pins
Relay devices can be primarily managed with four or five pins. Some common ones are occasionally referred to as 85, 86, 87, and 30. Pin 85 and 86 are for the relay coil, while 87 and 30 are for the switch.
Measure Coil Resistance
Connect the multimeter probes across points 85 and 86. An ideal relay has a resistance range of 50 ohms to 200 ohms. If the reading exceeds this range, it can result from a faulty coil, and you must replace the relay.
Check the Continuity of the Switch
Join the probes to pins 30 and 87. When the relay is not energized, you should ideally not have continuity (there should be an open circuit). If the multimeter gives a continuity reading, the relay is likely stuck and requires replacement.
Step 4: Energize the Relay
To test if the relay is functioning correctly, you need to energize it:
Use a 12-Volt Battery
Solder wires to the battery contacts and connect the other end to pin 85 and pin 86 of the relay. This will energize the relay, which in turn closes the internal switch.
Listen for a Click
When the relay is activated, you should hear a click. This sound indicates that the relay is working and the internal switch has been closed.
Test Continuity Again
With the relay energized, check for continuity between pins 30 and 87. This time, the meter reading should display continuity, meaning that the relay allows current to flow through it.
Step 5: Final Checks
After carrying out all the tests, you must remove the battery and all the jumper cables. If the relay passes all the tests, then it is working properly. If it fails any of the tests, you must use a new one.
Safety Tips
- Connect Power: Unplug the battery before removing or testing the relay to avoid electric shocks or damage.
- Take Care When Handling: Relays are delicate components. Be careful when handling them to avoid the risk of damage.
- Follow the Manual: For more specific directions and the specifications of your relay, read your vehicle’s service manual.
Conclusion
Testing an automotive relay is simple and requires only basic tools. By following these guidelines, you can ensure that the electrical systems in your car are in good working order and avoid unnecessary breakdowns while driving. Regularly testing and maintaining relays will save you time, money, and frustration in the long run.
Be aware that if you’re uncertain of the outcome or the accurate way to proceed, it’s advisable to consult a competent mechanic.
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