You’re probably used to the flawless engaging and disengaging of the car’s starter when the engine turns over that you don’t even think about it. Well, until it suddenly engages on its own as you drive!
Frightening, isn’t it?
What causes this? What should you do when this happens?
Read on to answer these and more questions. This post lists the possible reasons why your car starter may be engaging on its own that you may find helpful!
Plus, it offers some suggestions on what you can do to better handle the situation should it happen.
Note: Do not hesitate to contact a qualified auto mechanic.
What Causes a Car Starter to Engage as you Drive?
There are several possible reasons why the car starter may attempt to engage with the flywheel as you drive.
If you consider that the car starter motor engages when you turn the ignition to the START position then you can start to identify some possible explanations as to why the car starter may be acting this way.
I have listed some below (in no particular order) and hopefully, they can help you identify the cause.
1. The ignition switch is faulty and or the wire contacts are shorting. If the ignition switch wire connections are loose or there’s not enough insulation to separate them, there’s a risk that they can make contact and short when for example the car goes over a bump or as you shift gears.
Check when the car starter motor is engaged.
Does it happen when there’s vibration or the car goes over a bump? If so then this might be a probable explanation of why it’s happening.
Inspect the ignition switch contacts and confirm that they are firmly connected and they do not occasionally short.
2. The car starter relay may be faulty. Perhaps there is an internal short in the relay or the relay wire connections are loose?
Inspect the car starter wire connections and confirm that they are firmly connected and that there’s no short.
Look out for melted relay contacts too!
You may also be interested in this post: If the car engine will die while driving if the car starter is faulty
What Should you Do?
When you hear the whining, grinding sound of the starter gears locking with the flywheel, pull the car over when it is safe to do so.
Turn off the ignition to disengage the starter to prevent damage to it.
You may have to arrange a tow and have the vehicle thoroughly inspected to get to the underlying cause.
What Shows when Car Starter is Engaged?
When the car starter teeth engage with the already spinning flywheel, you’ll hear a screeching or whining, loud sound from under the hood.
This might be a one-off and may not repeat again.
Regardless, there is every reason to be concerned and to check the car again.
Following this, there’s always a risk that the starter may be damaged and you may not be able to start the car unless you replace it with another.
Look out for loosely connected and shorting wires, a faulty ignition switch, or a bad car starter relay should your car’s ignition switch attempt to engage as you drive.
Do not hesitate to contact a qualified mechanic for assistance.