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Symptoms of a Bad or Failing Ignition Relay

ignition relay

The ignition relay is one of the most important electronic relays found on modern vehicles. It is usually located in the fuse and relay panel beneath the hood, and is responsible for providing power to the vehicle’s ignition system, and some of the fuel system’s components. When the key is turned to the on position the relay is switched on and power is directed to the vehicle’s ignition and fuel system components, notably the fuel pump and ignition coils. When the relay fails or has an issue it can cause major problems with the operation of the vehicle. Usually a bad or failing ignition relay will produce a few symptoms that can notify the driver of a potential issue.

1. Car suddenly stalls while operating

One of the most common symptoms of a failed ignition relay is a car that suddenly stalls while operating. If the ignition relay shorts, burns out, or otherwise fails while the engine is operating it will cut off power to the fuel pump and ignition system. This will cause the vehicle to immediately stall due to fuel and spark being cut off. In some instances of a faulty relay the vehicle will be able to restart once the relay cools off, only to stall out once again after the relay overheats.

2. Car not starting

Another symptom of a faulty ignition relay is a no power condition. If the relay fails it will cut off power to fuel pump and ignition system, which will result in a no power, and therefore no start condition. You may find that turning the key may power on the accessories, and may even crank the engine, however the vehicle will not start due to there not being any power directed to the fuel and ignition system. Similar symptoms can also be caused by a wide variety of other issues, so a proper diagnosis is recommended in order to make certain what the issue is.

3. Dead battery

A dead battery is another symptom of a faulty ignition relay. If the relay has an internal short it may keep power fed to the ignition and fuel system, even when ignition cylinder is in another position, or the key is removed. This will cause the fuel pump and ignition components to remain powered on, drawing current, at all times, which will eventually lead to a dead battery. Aside from draining the battery this may also cause accelerated wear on the components, notably the fuel pump, due to having them powered on, but not operating.

4. Burned relay

In certain instances it may be possible for the relay to overheat to the point of burning up and melting. Apart from cutting off power to the vehicle’s ignition relay and causing performance issues, a burned relay may melt onto the fuse panel. This may make it difficult to remove, and in some instances can even lead to the replacement of the entire fuse box.

While servicing the ignition relay is not generally considered routine maintenance, it can sometimes fail and cause major issues for the vehicle. If you suspect that your ignition relay may be having an issue, have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if the relay should be replaced.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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