The braking system on every car is the one safety feature that must be in good operating order. It’s probably reasonable to say that you rely on your brakes just as much as you do on your car. Perhaps even more. However, there are situations when you’ll require the brakes to be applied. Do car brakes function when the engine is turned off? Yes, the brakes will still function, but not as well as they would under regular driving conditions. Instead of being helped by the engine like in regular driving, the braking pressure will be solely determined by the amount of pressure you apply to the pedal.
A vacuum booster is added to the braking system, allowing for proper braking with minimum driver involvement. The engine vacuum is used to create a massive amount of pressure in this booster.
If your engine suddenly stops running, the pressure in the circuit quickly diminishes, leaving just pedal pressure to provide braking power. Due to the lack of vacuum assistance from the engine, the pedal is extremely difficult to press.
If your car is idling and you quickly use the brakes, you may notice that the engine revs up to compensate for the increased power required within the brake booster assembly. This is how the engine pulls in additional air to create the vacuum needed for the booster function.
If your vacuum booster fails or the engine stops operating for whatever reason, the vacuum assist function is automatically off. You will be able to stop the vehicle at this point, but the amount of pressure required to activate the brakes will come from you, the driver, rather than the vacuum booster.
Yes, the brakes will still function, but not as well as they would under regular driving conditions.
Now that we’ve established that your car’s brakes work even when the engine is turned off, it goes without saying that your braking system must always be in good working order.
If you detect any unusual behaviour in your car’s braking system, it’s best to be safe and consult with a skilled mechanic who is experienced with your vehicle.