Why is My Brake Pedal Locked And Car Won’t Start?

Having your brake pedal locked and car not starting can be a frustrating and even dangerous situation for any driver. Identifying the root cause is key to getting back on the road safely. This concise guide will walk through the most common reasons for a locked brake pedal and troubleshooting steps.

Here’s a quick answer: The most common reason a brake pedal locks and the car won’t start is because the parking or emergency brake is partially engaged. This prevents the wheels from spinning freely to start the engine. Fully release the parking brake lever to resolve this issue. Other causes can be problems with the interlock system, low battery, faulty brake light switch, broken ignition switch or transmission linkage.

Main Causes of a Locked Brake Pedal

There are several potential culprits when it comes to a stiff, unresponsive brake pedal and inability to start the car:

  • Faulty parking brake – The most common cause is leaving the parking or emergency brake partially engaged. This prevents the wheels from spinning freely when trying to start the engine. Always make sure the parking brake lever is fully released.
  • Shift interlock system – Many modern cars have an interlock that requires the brake pedal to be pressed to shift out of Park. Issues with the shift interlock solenoid or brake light switch can prevent shifting and starting.
  • Dead battery – If the battery charge is very low, there may not be enough power going to the interlock system to allow the brake to be released and engine started.
  • Brake pedal switch – This sends an electrical signal when the pedal is pressed. If it is faulty, the signal may not reach the computer to allow starting.
  • Ignition switch problems – Issues with ignition switches and electrical connections can prevent the car from recognizing the brake pedal is pressed.
  • Transmission linkage – The transmission linkage or components being out of adjustment can prevent the car from shifting from Park.
  • Hydraulic brake problems – Issues like brake fluid leaks or air in the brake lines can cause brake pedal and starting problems.
  • Anti-theft system – If the security system detects an intrusion, it may go into lockout mode preventing the engine from starting.

Make and Model Specific Causes

Certain makes and models also have common issues that can lead to brake pedal and no-start problems:

Jeep vehicles

Faulty ignition switches that can cause no-start issues are common in Jeep models. The ignition switch sends power to the starter, fuel pump, ECM, and other key systems needed to start the vehicle. If it is damaged or worn out, it may fail to activate these components.

Electrical gremlins ranging from bad ground connections to failing alternators can also plague Jeeps. An undercharged or dead battery that results from this will prevent sufficient power to shift out of Park and start the engine.

Nissan models

A frequent culprit in Nissans is failure of the power steering pump. This electro-hydraulic pump provides pressure to disengage the shift interlock when the key is turned. If it is malfunctioning, the interlock may stay locked with the brake on.

The same power steering pump also provides hydraulic pressure to boost braking power. A failure can cause a stiff, hard to press brake pedal which could prevent starting.

Ford cars

A common and often gradual failure point in Fords is the brake booster check valve. The booster uses vacuum to increase braking force when the pedal is pressed. If the check valve leaks, vacuum is lost and braking becomes very difficult.

The brake booster failure will mimic symptoms of a locked brake pedal and prevent the engine from starting. Ford brake booster issues tend to appear over time versus suddenly.


Faulty brake light switches and shift interlock switches are well-known and widespread issues with VWs. Since these switches impact the ability to shift gears and start the vehicle, it is vital they are operating correctly.

The Comfort System Control Module is another component that commonly fails in Volkswagens. It controls the interlock that requires the brake pedal be pressed to shift and start the car.


Worn out clutch components are a common theme with Honda models. The clutch linkage must fully engage to put the transmission in the correct position for starting.

Damaged gears in the transmission itself can also prevent smooth shifting into Park or Neutral needed before startup. Transmission issues tend to occur most frequently in higher mileage Honda vehicles.

Solutions and Troubleshooting

If you find yourself with a locked up brake and no start situation, try these troubleshooting steps:

  1. Check parking brake – Make sure it is fully released and has not been inadvertently left on.
  2. Check for obstructions – Look for debris, objects or even ice blocking brake components. Remove anything obstructing motion.
  3. Check brake fluid – Ensure the brake fluid reservoir is filled to the proper level and not leaking.
  4. Check battery – Use a voltmeter to test battery charge state. Recharge or jump start vehicle if low power is suspected.
  5. Shift out of Park – Try shifting to Neutral or depressing the shift interlock override while turning the ignition.
  6. Consult a mechanic – If the problem persists, have a professional technician inspect the brake, electrical and drivetrain systems.


Does a dead battery cause brakes to lock up?

No, a dead battery does not directly cause brakes to lock or get stuck. Issues in the hydraulic system, brake calipers or parking brake would cause stuck brakes. A dead battery can however prevent releasing electronic interlocks that hold the brake on when in Park.

What should I do if my brake pedal is completely stiff?

If the brake pedal cannot be pressed at all, immediately contact a mechanic. This indicates a serious issue with vacuum assist, hydraulic pressure or the pedal mechanism. Driving with fully stuck brakes can lead to an accident.

Can I shift out of Park with a dead battery?

It may be possible to manually release the shift interlock using the override release lever or button and mechanically move the shifter. Consult your owner’s manual on how to do this safely for your make/model. A dead battery prevents electronically shifting out of Park in most modern vehicles.

Why won’t my push-to-start car turn on with a dead battery?

Push button start relies on battery power to activate ignition and start systems. If the battery is completely dead, the car will not have the minimal power needed to turn on and start with the button. Jump starting or recharging the battery is required.


In conclusion, a locked brake pedal and inability to start your car can stem from a number of issues, ranging from simple solutions like an engaged parking brake to more complex problems in the brake hydraulics or electrical system. Each make and model also tends to have common weak points. Try basic troubleshooting steps first like checking the parking brake, battery, and connections.

If the problem persists, have a certified mechanic inspect your vehicle’s braking and starting systems to properly diagnose and repair the specific issue. Addressing a locked brake pedal promptly is important, as driving with limited brakes can lead to very dangerous situations. Stay safe on the road by keeping your brakes and car starting systems well maintained.

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