Key Takeaways

  • Your brakes are supposed to be hard when the car is off.
  • If the car won’t start it’s most likely because of a dead battery.
  • Other issues like a bad starter could be the cause of your no start.
  • Brakes are vacuum assisted.
  • Hit a starter with a hammer in order to make it work again.

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You can tell a lot about a car’s condition through the feeling of a brake pedal. But why would the brake pedal be stiff but the car not starting?

Your brakes are supposed to be hard when the car is off. This is normal. If the car won’t start, it’s most likely a dead battery. Brakes are vacuum assisted, which makes them easier to push down. When the car isn’t running, the vacuum assist goes away, causing the brakes to get hard.

I’m a mechanic with five years experience of diagnosing and repairing vehicles. I am ASE certified and received my degree in automotive repair. I receive training on the latest automotive technology. And I use the latest tools and software to diagnose and repair vehicles today.

Table of Contents

Brake Pedal Is Stiff And Car Won’t Start

When your car is running, your brakes are vacuum assisted by what’s called a brake booster. This booster uses engine vacuum to assist the driver to add power to the brake system with their foot.

For example, the brake booster can add up to 1,400 pounds of pressure to a master cylinder line when it’s activated by the driver. And to activate it, all the driver has to do is press down on the brake pedal with their foot.

Most drivers are unaware that their brakes are vacuum assisted by a brake booster. Brake boosted brakes, or power brakes, have been in automobiles since people realized that humans can’t provide enough power with their feet to stop a car.

So engineers had to come up with a system to allow even the lightest of footed drivers to stop a vehicle, hence the vacuum assisted brake booster. But the thing about the brake booster is, it operates on engine vacuum.

And the engine can only create vacuum when the engine is running. So when you hit your brake pedal without the engine running, you're hitting your brakes without the vacuum assistance. This is what your car brakes would feel like without a brake booster.

This is a totally normal operation. Your brakes are supposed to be hard when the engine isn’t running. Now the vacuum booster does hold a reserve of three to four brake pedal pumps. This means when your car is off, your brakes will feel normal for three or four pumps, but get hard after those three or four pumps.

So after those three or four pumps are done, and your car is still off, your brakes will still feel extremely hard. This means you have an exhausted brake vacuum.

Now onto the reason your car won’t start.

Diagnostic Tricks

The main reason your car won’t start, probably, is that you have a bad battery. When you start your car, look for flickering dashboard lights. This is a tell tale sign that you have a bad battery.

Your car might not start because you have a faulty starter motor! This is an easy fix, since all you have to do to fix a bad starter motor is replace it. To replace it, you usually just have to unbolt the old one and bolt the new one in.

A bad starter motor will sound like a bunch of clicking coming from the engine bay. This clicking sound is your battery trying to push power to the starter motor through the starter relay, and the starter relay keeps clicking. A starter cable could have become detached or a magnet could have become broken.

A reason your car might not be starting is because of a damaged ignition switch. A damaged issue could stop power going from the battery to the vehicle’s ignition system. A bad ignition switch will cause a brake locked car, like the one you are experiencing.

Another issue could be a brake light switch could stop the car from starting. Brake lights are controlled by a switch that lets the computer know brake pedals are pressed down. If this switch is broken, the car will think the brake pedal isn’t being pressed on, and won’t let the car start.

Brake Boosters

Brake boosters generally last the whole lifetime of a vehicle. They never go bad. There are minimal parts in the brake booster. The fact that there’s minimal parts in the brake booster causes there to be minimal points of failure.

This means that the brake booster fails very rarely. To diagnose a brake booster, you’re going to want to feel for a hard brake pedal when the vehicle is on and the engine is running. And even if this is the case, it may just be a disconnected hose.

If you have a hard brake pedal while the engine is running, check to make sure the brake booster vacuum hose is hooked up. If not, it may be time to replace the brake booster. But take it to a mechanic to diagnose so you can be sure.

This is because there are other causes of a stiff brake pedal while the engine is running. But it’s very rare that the brake booster is bad. So if you suspect your brake booster is the issue, suspect again. Take it to a mechanic who can do a myriad of diagnostic tests.

With their tests, they’ll be able to tell you exactly what the issue is. Replacing a brake booster is a relatively easy job, but it’s not worth doing if the brake booster isn’t what needs replacing.

Starter And A Hammer

To test a bad starter, all you need is a hammer. That’s because the starter operates on a rotary device and magnets. When the rotary device gets stuck on a certain magnet, it has the potential to stop working.

This is why a hammer will sometimes alleviate the issues of a broken starter. Basically, what you’re going to want to do is smack the starter with a hammer. You want the internals of the starter to move.

But you don’t want to do serious damage to the starter so don’t hit it too hard. Hit it hard enough just to make a difference. Hitting the starter with a hammer has the potential to rotate the insides of the starter, making it work again.

If you can’t reach the starter with a hammer because it is buried too deep within the engine compartment, take a pry bar and touch the end of it to the starter. Once the pry bar is touching the starter, hit the end of the pry bar.

This will transfer the momentum of the hammer through the pry bar and into the starter, causing the internal motion you are looking for. Striking the starter with a hammer might seem archaic, but it’s a mechanic’s number one diagnostic tool in diagnosing a bad starter.

But don’t hit it too hard, as you can potentially crack the starter housing.

My Brake Pedal Is Stiff And Car Won't Start (How To Fix)

About The Author

Christopher Sparks

Christopher Sparks

Christopher Sparks has been servicing vehicles since 2012. After completing the automotive studies program at Camden County College, he was awarded an Associates's Degree in Applied Science. His first job was a lube-tech at Jiffy Lube, and is currently an independent B-Technician servicing vehicles for the United States Postal Service. Christopher is ASE certified and loves rebuilding engines.

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