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man in orange vest jump starting car on the side of the road

It’s frustrating enough to have to jump start a car, but having the alarm or horn going off too is nerve-shattering. So how do you stop the alarm from going off while getting your car back on the road?

There are a few reasons why the alarm or the car horn goes off while jump starting. Solving it may be as simple as clicking the Lock/Unlock button on your keychain fob to reset the alarm system. However, if there’s a problem with the electrical or the anti-theft systems on the vehicle, resolving the issue may be more difficult.

This article explores possible causes of the car horn going off during the jump starting process, and what you can do about it.

What Causes the Car Horn To Go Off While Jump Starting?

The causes for a blaring horn or alarm while jump starting the car can usually be traced back to the type of system you  have. For example:

  • An engaged anti-theft system may consider a jump start to be a form of vehicle tampering.
  • Cars with alert systems will sound the alert for the open doors and hood of the car.
  • Hi Tech fob systems will react if they can’t ‘read’ your keychain fob for some reason.

These problems are generally easy to fix or work around. However, it can get more complicated.

Examples of more complicated problems include:

  • A faulty alarm connection
  • A wiring issue
  • A damaged relay or component

How Can I Stop The Horn From Going Off While Jump Starting?

It’s easiest to stop the horn from sounding if it turns out to be a regular function of the alert systems for the car. In that case, it’s just a matter of working around the issue.

First Things First: Figure out what the issue is. Is it the anti-theft system, the general alert system, or a Hi-Tech warning system?

Once you know that, you can apply some of the following solutions.

Trigger #1 – An Engaged Anti-Theft System:

Anti-Theft Systems are there to prevent tampering. What it means when the car battery dies, however, is that one of two things will happen:

  1. The system assumes that charging or removing the battery to charge is a sign of tampering.
  2. The system is engaged when the car dies and returns to the engaged mode when the power is restored.

Either way, there are some simple solutions that you can start with.

Solution #1 – Try Resetting The Alarm:

Use the key or the electronic fob to lock and unlock the car to reset the alarm to the deactivated mode. It should only take a couple clicks, for the alarm to stop blaring.

At that point, the car will recognize you as the valid owner, and it should let you finish charging the battery in peace.

Solution # 2 – Try Removing The Battery:

Sometimes it’s just easier to charge the car battery while it’s disconnected from the rest of the car. If your alarm is persistently giving you trouble during the jump starting process, try taking the battery out to charge.

That way, even if the horn reengages when you put it back, you can focus on deactivating the alert, as opposed to working with that, and trying to jump start your car. It also means that your alarm won’t be draining the battery during the process by trying to alert you to a problem.

Solution #3 – Forcibly Disengage or Disconnect The Alarm:

If the horn will just not stop sounding no matter what you do, you may need to find a way to forcefully disengage or disconnect the unit. However, if this is required, you’re more likely looking at some sort of electrical or technical malfunction that will need repairs later on.

Trigger #2 – A Basic Alert System:

By basic alert system, we’re talking about the systems that beep or honk to let you know when the lights are on, or if the doors are left open. To get around it, you can try the following solutions:

Solution #1 – Shut All Doors and Hatches

Sometimes, the alert will simply be responding to the open doors or the raised hood of the car. If you close all the doors, the back hatch, and gently lower the front hood, it may stop on its own.

It’s also a good idea to double check and make sure there are no lights left on. Even if the battery is dead, the connected circuit might cause the car to start sounding the alert as soon as power is available.

Solution #2 – Try Removing The Battery

If you remove the battery from the car, you can then turn off the lights and close the doors, and charge the battery at your leisure. You may still have to deal with a brief round of noise when the car battery is replaced, but it won’t last as long.

Solution # 3 – Disable the Alert System

If neither of these solutions work, there may be a short or other malfunction in the electronics of the car systems. It may include a malfunctioning sensor on one of the doors. If that’s the case, then you’ll need to take it in for a diagnostic to determine what, exactly, the problem is, and how to address it.

As a short term measure, you may need to disable the alert system, and might even have to go as far as disconnected the lights to stop the alert system from going off at every opportunity.

Trigger #3 – A Malfunctioning Fob Or Hi-Tech System:

Some newer model cars no longer use keys – instead they use electronic fobs for all the locking and alert systems of the vehicle. In terms of convenience, this is handy, but it can also cause a problem if the fob itself loses power or begins to malfunction.

Some alert systems will automatically assume the car has been stolen if they can’t sense the fob. Therefore, when trying to jump start the car, the alert will go off, and you won’t be able to disable it by traditional means.

The solution is simple:

Solution #1 – Replace the Battery or the Entire Fob

Once the battery or the fob is replaced, the problem should be resolved. If replacing the fob or the battery doesn’t work, then it may be an issue with the internal sensor of the car, and require a professional diagnostic.

What Else Might Cause the Horn to Go Off During a Jump Start?

If you’ve tried all the regular solutions and you’re still having the same problem, it’s time to look deeper. At this point, it’s likely to be a malfunction caused by:

  • A sensor gone bad
  • Corroded and damaged wiring
  • Malfunctioning electronics
  • Faulty or loosened connections

These issues can be a lot tricker to diagnose and solve, and the difficulty varies from model to model.

What to Do If It’s a Wiring or Electrical Issue

If you suspect that the issue is a deeper problem, such a matter of malfunctioning electronics, then the first step is simple.

Find a way to get your car to a dealership, auto shop, or repair shop and have them run a detailed diagnostic on it.

Malfunctions in the electrical system can be incredibly difficult to diagnose and find. It generally requires a professional with the proper equipment to track an electronic problem in the car’s systems.

The more infrequent the problem, the harder it is to identify. Once you have diagnosed the problem, you can take further steps.

When to Contact a Professional Mechanic

Generally, you can fix most problems at home. Others will require a professional touch. And with some, you may need to consider replacing the entire vehicle. If you have the following problems, you’ll most likely need a professional mechanic to solve the problem for you.

  • Corroded or Damaged Wiring
  • A Bad Sensor
  • Malfunctioning Electronics

These components can be hard to find, and harder to replace. It takes an experienced hand to get these replaced properly to get your car to stop making unwanted noises.

When to Consider Vehicle Replacement

You can replace most of the parts, but some elements may cost more to replace than the car is worth.

If the problem is a malfunction in the core electronics, or in the main computer system of a newer car, it can be impossible to fix without rewiring a large part of the car.

Programming or hardware problems are generally expensive and complicated. We don’t recommend trying to fix these yourself.

Frequently Asked Questions:

Can I Disconnect the Alarm or Alert System Until It’s Fixed?

We don’t recommend it, but it is possible. There are owners manuals out there that can show you how to disconnect a malfunctioning alarm or alert system. You will still need to take it to a shop or replace faulty components.

What Can I Do If I Need My Car, But There’s A Problem With The Fob?

If the problem is a fob sensor in the keychain, or the car, there’s not much you can do. First, you will need to replace the sensor. A rental car or other form of transportation may be necessary until you address the matter.

Does The Car Alarm Going Off Drain The Battery?

If all the relays and connections are working properly, then no. An alarm might draw a slight bit of power and give you a headache. However, it won’t drain the battery faster than the charger replenishes it. If you think your alarm is draining your battery, then there might be an electrical problem somewhere. In this case, it’s best to have a mechanic take a look.

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