How to test a car relay with a 9v battery. Check for continuity between terminals 30 and 87. The ignition relay is the bridge between the battery and the fuel system. You want to use either a 12V battery or voltage regulator to test the relay. If these currents are present then the relay is definitely the problem. Depending on the circuit it controls, ... Connect a jumper wire between the battery positive terminal and one of the control circuit terminals on the relay. If the relay passes all the tests it is good and the problem exists elsewhere in the fuses or vehicle wiring. Try the switching the + and – positive and negative terminals if … The relay prevents electrical accessories from draining energy by disrupting the power supply. Connect a test lead, which is a wire with an alligator clip on each end, from relay terminal 86 to the negative terminal of a 12 volt battery. If a component that is fed with electricity through a relay (See How car electrical systems work) terminal of the battery to the feed terminal on the component, thereby bypassing the relay and supply wiring. This article shows you how to test a relay. Step 1 - To test for intermitted relay failures which are common, remove the relay in question, take a small wire strand, about two inches long and insert it into the relay connector terminal 87 or 30. How To Test A Relay Using Multimeter & Battery? Determine relay number and pin out. Relays switch the power to high current drawing devices to minimise the distance that large gauge wires must run to cut down on weight and cost. Connect a test lead from relay terminal 85 to the positive terminal of the 12 volt battery. Grasp the relay firmly with your fingers and pull it straight up out of its socket to remove it from the vehicle. To wire an automotive relay, make at … Check the starter relay wiring one more time and then test by attempting to start the vehicle. The set of contacts that are open when the relay is not energized are called normally open (N/O) contacts and the set of contacts that are closed when the relay is not energized are called normally closed (N/C) contacts. Use these tips to learn how to test a 4 terminal relay. The magnet closes the second independent circuit within the relay that runs between pin 87 and 30. For example, if you have a 12V battery, test it using the 20V setting. Troubleshoot any particular relay in your car and find out whether you actually need to replace it. Connecting a 12V Relay to Arduino: To connect a 12V relay to the Arduino you need the following things: - 1 Arduino - 1 diode for example 1N4007 - 1 NPN transistor for example 2N2222 (in the US) or BC548 (in Europe) - 1 relay for example one with coil voltage 12V and switching vo… The relay will close, and you should get continuity between the two pins that the meter is connected to.You should also hear a clicking noise coming from the fuel pump relay. If an open load is observed, test the triggers by disconnecting the wires going to them. A relay will usually have a coil, pole terminal and a set of contacts. Auto Repair & Mechanics : How to Test a Car Relay - YouTube A 12-volt circuit is usually connected to a battery or a transformer. Find the particular relay you want to test. If the voltage you read is not 12V when the ignition switch is turned on, the starter relay is faulty. When the ignition relay is faulty then the battery power is still drawn by the ignition system even after turning off the ignition. There should not be continuity between these terminals. Test for continuity between terminals 30 and 87. At best you will get false readings, at worse you will damage or destroy your tester. Sometimes, but rarely, relays do fail. A 12 volt relay is an important component in the electrical system of modern cars and trucks. You may find another relay in your car with the same configuration — arrangement and number of terminals — as your fuel pump relay. Touching the probes to each end of a device or circuit automatically tests for continuity. Connect the other alligator clip to the remaining trigger, and place its free end on a 12V source. The relay draws very little power to perform the switching, a A mechanic and truck driver for more than 40 years, Lowell is able to write knowledgeably on many automotive and mechanical subjects. Step 1. A continuity tester is a battery operated device that either lights up or buzzes when a circuit is continuous. Check both power supplies to the relay to confirm the presence of 110v AC and 12v DC. Could i make 12v battery low voltage disconnect with relay and resistor? As the name implies, a battery protection relay keeps the battery from becoming discharged. Connect 12 V supply to Control pins on the relay and listen for a physical click (Gross Test). Using the continuity tester, test for continuity between relay terminals 85 and 86, which are marked on the relay. It came off a Nissan Sentra 99 Test the Relay Contacts using Multimeter: Beside that technique of finding the relay functionality, you can use this method also. Connect your ground connection on the power supply to the ground pin on the relay.Touch the power supply's trigger to the input pin. Step 2 - Next, reinstall the relay while keeping the wire strand inserted and clear of any other terminals or metal (ground). There should be continuity between these terminals. It depends on what you want to test (since you said “test”). Most 12 volt relays operate accessories in a motor vehicle. Testing a car relay involves the use of a 12-volt source, such as a car battery, and a multimeter that is capable of reading resistance. Another way to test for resistance by use of a wire jumper. Copyright 2020 Leaf Group Ltd. / Leaf Group Media, All Rights Reserved. When you place the 9 volts battery on the relay coil terminals, the relay will click. Lowell is a freelance writer who has been writing professionally since June 2008, with articles appearing on various websites. The relay test is done with a 213 relay from a Porsche 944 Turbo. There should be continuity between these terminals. Estimating the voltage this way makes the test result more accurate. Fortunately, a car relay is easy to test. best way to test a relay is remove it from board, get a 9v square battery and touch the switching terminals on the relay, the relay should click if its working. Pin 87 is where high-amperage current from the battery enters the relay. In this post, I am going to teach you how to test a relay with a multimeter . Connect a test lead, which is a wire with an alligator clip on each end, from relay terminal 86 to the negative terminal of a 12 volt battery. Relays switch the power to high current drawing devices to minimize the distance that large gauge wires must run to cut down on weight and cost. 12 volt relais, relay image by Sascha Zlatkov from Fotolia.com. You will notice that even if the battery is new and working fine it is always drained of power especially in the mor… A relay that passes this test will probably be ok, but if you still suspect the relay you can easily verify finer electrical properties by continuing. Replace the relay if any of the continuity tests fail. Check for 12 volts at the relay input to the coil with the meter’s negative on the frame of the vehicle. Connect a test lead, which is a wire with an alligator clip on each end, from relay terminal 86 to the negative terminal of a 12 volt battery. Squeeze the clip to open it and release it to attach to the terminal and battery. If you want to switch with a 9 V battery, use a relay with a 9 V coil, as @BobK implied in post #4. Generally these two terminals will be the smallest terminals on the relay. Test Function 2. And one of the best ways to do this is to use a multimeter with an ohmmeter setting and then measuring the resistance values. Any reading of voltage below 9.5 volts, or if the battery holds a good record for a while and steadily drops, or even when it falls instantly to 0 volts, then it means there is a problem, and the battery should be replaced due to its low capacity . 1. Place an alligator clip on one trigger and connect the free end to ground. If the component still does not work, it is faulty; if it works, then the supply is faulty and the fault will be in the relay or the connections to it. Using a relay also means a lighter duty switch is used, further cutting cost and weight. Squeeze the clip to open it and release it to attach to the terminal and battery. Testing a 12 volt relay is easy and requires a minimum of tools and time. Never attempt to test for continuity when the relay is plugged into the vehicle. How To Test A Relay With A Multimeter. A 4 terminal relay is used so a low power circuit may engage a high power circuit without risk of damage to the low power control circuit. A 12 volt relay is an important component in the electrical system of modern cars and trucks. In this article, we will show you “how to test a relay“. Or does it matter since the relay is such a simple device? So it is crucial to test a relay if it stopped working before you replace it or throw it away. Just place the battery on the relay terminals that are connected to the relay coil. If the vehicle won’t start, check for a strong click from the relay when it is initiated. There should now be continuity between these terminals. A 12 volt relay is an important component in the electrical system of modern cars and trucks. Relay should operate properly from this arrangement, and the extra voltage won't harm the LEDs with the 470 Ω resistor limiting the current. A relay usually gets damaged due to a number of reasons. Its Terminal Identification & Operation. If one or both of the voltages are not present then you need to check your electrical circuit because it is likely the problem lies there. You should feel and hear the isolator click and the meter should read 0 ohms. The Fastest Way to Test a Fuel Pump Relay or Other Automotive Relays By far, the easiest way to test a suspect fuel pump relay — or some other automotive relay — is to swap the suspect relay with a good one. Bad contact points can cause a voltage drop. For your battery to pass a load test, the multimeter must read between 9.5 to 10.5 volts straight for 30 seconds when the battery is tested. K.K. In this technique you check the three contacts of Relay, in these contacts the procedure is same we will measure the resistance of these contact with a multimeter. The relay draws very little power to perform the switching, allowing the wires carrying the control voltage to be very small. Relays switch the power to high current drawing devices to minimise the distance that large gauge wires must run to cut down on weight and cost. Applying a small amount, as low as .2 amps of current to the relay coil closes contacts to feed power to an accessory that requires more current to operate, usually over 20 amps. The purpose of testing a relay is to find, whether it is good or bad . Using the continuity tester, test for continuity between relay terminals 85 and 86, which are marked on the relay. The test procedure is as follows. He is currently pursuing a degree in English. Power from the switch flows into the relay at pin 85 and out to a chassis ground from pin 86, making a complete circuit that activates the relay’s electromagnet. Connect the wire between the battery lead and the ignition circuit lead. Disconnect Relay For example, a low power circuit in a car that commands the high power headlights to come on would send the command through a 4 terminal relay. Using any settings beyond that would lead to a less accurate result. The battery could be unintentionally depleted by an accessory device that was left … Could an AC/DC adapter at 12 Volts x 1 Amp work also? Test the relay’s voltage at the switch. Connect a test lead from relay terminal 85 to the positive terminal of the 12 volt battery. I want to test a pretty common relay with 12 Volts but I dont know if its safe to use the car battery, isnt that too much Amperage? When the coil is energized, the NO terminals, close and let electricity flow. I was thinking if put resistor in series with relay coil i could lower current so relay would barely work on 12v but when it drops to 10v voltage after resistor would be so sma… Most modern multimeters are autorange, meaning they set the proper range once you begin the test. Find out how to listen for clicks and tones that indicate a functioning relay with help from an auto mechanic in this free video on car repairs and mechanics.Expert: J.B. HebertContact: www.wrxtra.comBio: J.B. 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