Nissan Sentra Won't Start, Brake Locked. What's Wrong?

When the Sentra doesn't start and the brake feels locked, usually, it's all about the brake switch but some other problems can also be the culprits. You need to inspect the car and find the problem before you can start it and drive. Otherwise, the engine will refuse to start as it thinks that the brake pedal is not being pressed.

No-start and stiff brake problem highlights

• Level of urgency:Medium
• Can you drive?Obviously, no
• DIY inspection:Possible
• DIY repair:Impossible
• Price for repair:$350 - $800
• Common Reasons:Engine won't start, vacuum won't build up
• Ways to fix:Solve the no-start issue, thebrake pedal will be solved automatically

Explaining the problem with stiff brakes and no-start in the Sentra

This appears to be one of the common problems in the Sentra and several other Nissan cars. I will explain to you why this happens before giving actual tips on how to deal with the problem.

So, to successfully start your Sentra, you need to go through several steps:

• Get into the car. It means you have the needed key because the majority of Sentras are equipped with keyless entry and engine start systems.
• Register the key. You don't need to do anything, the key fob is communicating with the car even before you get into it, so the vehicle already knows that it's you.
• Press the brake. Without this, you will not be able to start the engine. If you don't press the brake and then press the start button, you will activate the accessory mode and will be able to use all the functions of the car but the engine.
• Press the start button. If all of the above are completed, you will be able to start the car by pressing the engine start button.

So, if the engine doesn't start, you need to find the problem in these steps. Given you are already in the car, there shouldn't be a problem with the key fob. Additionally, you would see an error message like Key ID Incorrect or something like that if the system couldn't see the key fob. If you see no error messages, this is obviously not the actual reason.

There is only one thing left - the brake system. Your car just doesn't understand that you are pressing the brake and it turns on the accessory mode instead of starting the engine. There are several things that can cause this and you will need certain attention to some units to try and solve the issue.

What are the possible reasons for the no-start problem in your Sentra?

So, we aren't looking at all no-start issues, but only at the certain one: the brake pedal is stiff, the car doesn't start but the accessory mode is on when you press the engine start button. There are several culprits and one of them is the most common.

Here are the problems that can cause this issue:

1. Brake pedal switch problem

This is the most common culprit of this problem. Even though it doesn't affect the stiffness of your brake pedal, the pedal actually has to be stiff when the engine is not started yet. And it's always stiff. You just didn't pay attention to it before because the engine started and the pedal became softer immediately.

So, the switch is located in the upper part of the pedal. You will easily locate it if you look under the front panel and eventually see the unit that is pressed by the metal lever of the brake pedal when you press it. This is a simple sensor that is activated by the pedal movement.

This sensor tells the electronic control unit in your Sentra that the brake pedal is pressed. If the sensor is broken, the car just thinks that you didn't press the brake pedal and it will switch on the accessory mode once the engine start button is pushed. No warnings, no errors, just the accessory mode.

So, there are two main reasons why this sensor may go bad:

• it's not the part of the highest quality, so it can just be worn out at some mileage;
• it may be affected by water when cleaning the car and the wire connections may develop some corrosion.

Although the problem is pretty serious and it may leave you stranded in a perfectly working vehicle, there are several ways you can solve the issue and I will tell you about them later in this article.

2. Poor battery

If the 12V battery is very low, the voltage in the system will be lower than needed for proper operation. All sensors and electronic control modules highly depend on the battery. It should work well and supply all the systems with the proper voltage. But if it malfunctions, you may see all kinds of different error messages and glitches.

If the car doesn't start but everything else works well, it may mean that the vehicle just lacks the power to crank the engine. While the battery may supply power for lights fans, and even music, it can't power the starter motor.

3. Problems with wiring and connections

Every sensor is wired directly to the electronic control unit that it sends all the needed readings to. The physical wire can be damaged by water or can corrode just because of its age. Connections are prone to different kinds of damage.

I have to note here that Nissan cars are not the top-quality ones in terms of wiring and connections. They may develop many different wiring issues. But if you can't start the car and the brake pedal is stiff, you should check the wiring that connects the brake switch to other units of your vehicle first.

4. ECU problems

It's not that common but anyway worth checking if the problem is still not located. The ECU gathers the needed signals from different car sensors and makes sure that the engine is ready to start. Until it gets the signal about the pressed brake pedal, it will not tell the engine to start however hard you press the start button in your Sentra.

If the ECU malfunctions, you may need to reset it. If the hard reset won't work, you may need to take your car to the dealer and have it reprogrammed. Sometimes, the ECU may need to be changed. This is the work for professionals only.

By the way, if you see the message about the blocked front sensor and the cruise control is failing, read this post about the ICC and FCW failure in Nissan - a very common problem with all cars of this brand that have the intelligent cruise control system.

What can you do to fix the Sentra if it doesn't start?

So, now you know about the most common reasons that can cause this problem in your Nissan Sentra. But how do you fix the issue?

Well, there are several things you can try:

• Reach the brake switch with your hand and move the wiring. This may help the car restore the connection with the sensor and it may start eventually.
• Take the switch off and then put it back on. Also, don't forget to disconnect the switch so that it can reset its readings.
• Go out of the car, lock the doors, wait for a minute, unlock the doors, and try starting the car. Sometimes, the so-called key cycle will help you solve the problem.
• Disconnect the battery for 4-5 minutes. This may help you reset the ECU and try solving the issue with the control modules' operation.
• Charge or replace the 12V battery. This is another way to try and solve the problem. You can charge the battery or buy a new one and try to start the car with proper power in the system.

Final thoughts

Although this is not a huge problem and can be solved easily, the no-start issue and stiff brake pedal in your Sentra may scare you. After reading this article, you will probably be able to try all DIY tricks to bypass this thing or solve the issue right there and then. If nothing helps, you may still need to plan a visit to the dealership.

Even if you managed to start the car after playing with the switch, you still need to go to the shop and have this switch checked and maybe even replaced.