One of the most important – and most forgotten – components of any vehicle's ignition system is the starter relay. This electrical part is designed to redirect power from the battery to the starter solenoid, which then activates the starter to spin over the engine. The proper activation of this process allows the ignition switch's circuit to complete, which will permit you to shut the vehicle off when you turn the key off. Although it's unlikely that you'll ever experience a problem with the starter relay, it is prone to mechanical failure and will need to be replaced by a professional mechanic if it wears out.
Most of today's modern cars and trucks have an electronic ignition switch that is activated by remote key. This key has an electronic chip embedded that links up with the computer on your vehicle and allows the ignition button to activate. There are times when this type of key will impact the operation of the starter relay and display similar warning signs as if this system is damaged.
Listed below are a few of the symptoms of a damaged or worn out starter relay. If you notice these warning signs, make sure you contact a local ASE certified mechanic to completely inspect your vehicle as these symptoms might indicate problems with other components.
1. Vehicle does not start
The most obvious warning sign that a problem with the starter relay exists is when the vehicle won't start when you engage the ignition process. As stated above, electronic keys do not have a manual ignition switch. However, when powered, it should send a signal to the starter relay once the key is turned or the starter button is pressed. If you press this button or if you turn the key on a manual ignition switch and the vehicle does not turn over, it may be caused by a problem with the starter relay.
This problem may be attributed to a circuit that has failed, so no matter how many times you turn the key, the vehicle will not start. If the circuit has not yet completely failed, you may hear a clicking noise as you try to turn the key. In either case, you should contact a professional mechanic to inspect the symptom and correctly diagnose the precise cause.
2. Starter stays on after engine started
When you start your engine and release the key or stop pressing the starter button on a modern vehicle, the circuit is supposed to close, which will discontinue power to the starter motor. If the starter stays on after the engine has ignited, the main contacts in the starter relay have most likely welded together in the closed position. When this occurs, the starter relay will be stuck in the on position and damage will occur to the starter, circuit, relay, and the transmission flywheel if it is not addressed immediately.
3. Intermittent issues starting the vehicle
If the starter relay is working properly, it will send power to the starter every time it is engaged. However, it is possible that the starter relay will become damaged due to excessive heat, dirt, and debris or other issues that might cause sporadic operation of the starter. If you try to start your car and the starter doesn't activate instantly, but you turn the key switch once again and it works, this is most likely due to a problem with the relay. In this case, it's important that you contact a mechanic as soon as possible so they can determine what is causing the intermittent contact. In many cases an intermittent starting problem is linked to a bad wire connection that may become dirty due to exposure under the hood.
4. Clicking sound coming from the starter
This symptom is common when your battery is low on amps, but is also an indicator that your starter relay is not sending a full signal. The relay is an all or nothing device, meaning that it either sends the full electrical current or sends nothing to the starter. However, there are some occasions when a damaged starter relay will cause the starter to make a clicking sound when you turn the key.
The starter relay is a very durable and reliable mechanical part, however it is possible for damage to occur requiring a mechanic to replace the starter relay. If you notice any of these warning signs, make sure to contact one of the professional mechanics at YourMechanic.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Starter Relay and was authored by Timothy Charlet.