Why do relays click

One of the most common symptoms of a failed ignition relay is a car that suddenly stalls while operating. Car not starting. Dead battery. Burned relay. If your starter relay has gone bad , the electrical signal will never make it from the battery to the starter motor. As a result, your engine won't turn over - no matter how many times you turn the key. A faulty relay often produces an audible clicking sound when you turn your car. Listen for a click when the relay is energized.

Check the energized condition of the relay contacts. Use a digital multimeter DMM to test the resistance between each pole of the relay and the corresponding NC and NO contacts for that pole. All NC contacts should read infinite resistance to the corresponding pole. Despite this, sometimes the ignition relay can fail due to wearing, accident, damage or exposure to water.

A bad ignition relay will not only cause starting problems to your vehicle, but it can also cause stalling or the vehicle, draining and damaging of the battery and the power loss in the dashboard lights. As you can see, relays most commonly fail in the "stuck open " position where the mechanical switching element fails to close and the relay fails to carry a current.

Relays are less likely to unintentionally close or remain closed after the switching current is released. A faulty or unreliable charging system can also drain the battery while the car is running. Alternators with bad diodes can cause battery drain. An alternator with a good diode allows current to flow in one direction. If the relay is in a metal housing, It may have only ONE pin for the coil. The second pin, or ground is the housing which must be mounted direct to chassis or otherwise grounded.

If your relay is in a plastic housing it will have 2 pins for the coil, usually reversible. What about also why did it take so many tries for the fuel pump to come on?

A relay is an electronically activated switch. Inside is a coil. A relay can be checked with a jumper wire, voltmeter, ohmmeter, or test light.

If voltage is not present, the relay coil is faulty. If voltage is present, continue testing. One of the most obvious signs that the AC relay may have a problem is that the compressor is not coming on at all. In most cases, when the AC is turned on you will be able to hear the compressor switch on.

You need to figure out which. To test the relay itself, take two wires, each about a foot long with a female spade terminal at one end and stripped at the other end. Attach the other to relay terminal 85 coil ground. You should hear and feel the relay click. Replace it. For extra credit, you can set a multimeter to measure conductivity resistance and connect it across relay terminals 30 and When you touch 86 and 85 to the battery, the electromagnet pulls the switch contacts together, so the resistance between 30 and 87 should read essentially zero under one ohm.

If the relay does click and 30 and 87 do show continuity, there is still the possibility that the internal contacts are corroded and a voltage drop across them is preventing full current from flowing. Take that thought and park it for a moment. If the relay itself tested as good, then the relay wiring must be tested next. Consult the DIN table and the figure above. Test the low current control side. Set the multimeter to measure voltage, connect the black probe to ground, and use the red probe on socket terminal Turn the circuit on e.

Then test 85 by setting the multimeter to measure resistance, probing socket terminal 85, and making sure that there is continuity between it and ground. Note that if the circuit is for a horn, most horns are switched on the negative side of the control circuit, not on the positive. That is, on a horn, 12V should always be present on 86, and 85 is grounded when the horn button is pressed.

If the control side fails either of these tests, you must troubleshoot the wiring. Often it is a problem in whatever is switching the control side on and off. For example, on a horn, the problem is often in the spring-loaded plunger behind the steering wheel that touches the ring contact that grounds terminal Look at the terminal labels on the relay.

They are identified as 30, 85, 86, 87 and 87a , if it is a five-terminal relay. Terminal 30 receives constant battery voltage. Terminal 85 is the relay's connection to ground, 87 and 87a are the output terminals for whatever the relay controls and 86 is the power to the control side of the relay. Identify the slot in the fuse box that terminal 85 plugs into. Set your multimeter to read voltage on the volt scale. Plug the negative lead of your multimeter into the slot for terminal No.

Touch the positive lead to the positive battery terminal. You should see constant battery voltage. If the voltage flashes, repair the ground and ground wire that connects to terminal No. If you get a constant voltage, continue to the next step. When touching the test leads to the battery terminals, hold the leads by their plastic handles to prevent accidental electrocution.