The Ford Fusion is a stylish midsize car that was produced from 2006 to 2020.
Like any car, the Fusion is susceptible to nuisance alarms.
If your Ford Fusion alarm keeps going off, check out potential solutions below.
Table of Contents
Why Does My Ford Fusion Alarm Keep Going Off?
A Ford Fusion alarm is usually triggered by a faulty door or hood switch. Other common causes are 12V battery issues, a defective anti-theft system, key fob problems, and even cold temperatures.
1. Malfunctioning Door Switches
Faulty door switches are a common cause of random alarms on the Fusion. These switches (or sensors as they are also called) monitor the open/closed status of the door – if damaged, faulty or dirty they can send false readings thereby triggering the alarm.
Door switches are a common point of failure as they are subject to wear and tear due to the doors being continually opened/closed/slammed etc.
The door latches and door switches can get dirty too which can cause issues, so the first thing you should do is give all door latches a good clean and spray some WD-40 on the latch and work it in to see if that helps.
Also check the wiring leading from the body into the door for any signs of damage, it should be in a flexible hose on the hinge side of the door.
If you suspect the alarm issues are linked to the door switch, ask your dealer to run a diagnostic test to try and pinpoint the fault.
On CarGurus.com, we found these comments by Taurus owners:
“Every so often my indicator light on my dash will read Rear Right Door Ajar and my interior lights will not shut off. When this has happened I end up having to just disconnect the battery but it’s only been a temporary fix. I’m guessing I have a bad sensor in my rear door or something…”
“Alarm goes off all the time, it is a sensor in the rear pass door that no one has been able to fix! It has been replaced and still does it! As far as I know there is not an independent fuse for it, if you pull the fuse you will no longer have reverse lights either…”
One Taurus owner talks about this matter on the r/MechanicAdvice subreddit:
“You need to plug in an advanced scan tool and examine the door switch operation. It could be a dirty contact, slightly misadjusted door or door latch. The door ajar switches are in the door latches…”
2. Faulty Hood Switch
A faulty hood switch is a common cause of unwanted alarms for Ford vehicles (Fusion included).
The switch is typically embedded in the hood latch.
The small electronic device is designed to detect whether the hood is open or shut and is an important part of the car’s alarm system – if it is broken, loose or dirty it can send false readings to the car’s computer thus triggering the alarm.
- Pop the hood and locate the hood switch.
- Check for any obvious damage, rust or loose connections.
- Give the hood switch a clean too (use contact cleaner), as dirt and grime can cause issues.
- You can test the switch with a continuity tester.
If you are well-versed mechanically, you can buy a new hood switch online and replace it yourself. Otherwise, we’d advise visiting your local mechanic.
This issue was mentioned by a couple of owners on the Reddit.com/r/FordFusion subreddit:
“It could be that you need a new hood latch. I had this same problem on my Fiesta and that was the fix it needed…”
“Well, a failing latch sensor on the hood would trigger the ajar notification and “popping” the hood will set off the alarm…”
3. Drained 12V Battery
A faulty or weakened car battery causes a variety of problems, including accidentally triggering the Fusion alarm.
The best thing to do is take your Fusion for a battery health check, these are usually quite inexpensive or sometimes free such as at AutoZone.
Or you can test it yourself with a multimeter (see the guide at the end of this article).
A healthy 12V battery should be about 12.6 to 12.8 volts while a weakened battery reads below 12 volts.
“Ok solved for now. I disconnected the battery (again) and charged it overnight. It wasn’t dead but was charging at 3 volts out of 6 volts setting on the charger, so it wasn’t full either… I guess the lesson is if anti theft drains your battery you might have to disconnect and recharge it overnight. Boosting did not do it for me.” – Reddit.com/r/FordFusion
4. Loose or Bad 12V Battery Connections
Loose or bad 12V battery connections can cause a number of problems, including triggering the alarm of your Fusion.
A bad connection can be caused by dirt or gunk buildup.
The terminals may have come loose from driving and vibrations etc.
Make sure the engine is off before doing any work on the battery.
- Inspect the battery and look for any signs of damage, dirt build-up, rust, or corrosion.
- Disconnect the battery and loosen the nuts on the clamps using a wrench.
- Remove the negative clamp, marked with a “-” first.
- Clean the terminals with a toothbrush dipped in a mix of baking soda and water, rinse with distilled water and dry with a cloth.
Reconnect the battery, ensuring tight connections.
A Ford mechanic on JustAnswer.com had this to say:
“Your best option is going to be to disconnect battery terminals for a longer period or contact a locksmith who can try to get keys programmed. These newer vehicles require scan tools to access the modules data. The best we can do is check fuses, check terminals for corrosion/rust, load test battery (preferably replace with new), or scan the vehicle.”
5. Faulty Key Fob
Another reported cause of nuisance alarms on the Fusion is a faulty key fob.
If you have 2 remotes, try taking the battery out of one and use the other for a while.
If the alarm problems persist, and you have tried cleaning the inside of the fob(s) and changing the battery, the best thing to do is speak with your dealer.
Below is a suggestion posted on FordFusionForum.com:
“Buy a key fob with the built-in key. Since you do have two keys, you should be able to program it yourself with the procedure in the manual. The fob’s code is tied to the key, so it should work once learned…”
6. Accidentally Pressing the Panic Button
Another common reason why the Taurus alarm is triggered is accidental pressing of the panic button located on the vehicle’s key fob. To stop the panic alarm, you must press the panic alarm button again.
It can easily happen when you are carrying a lot of items in your pocket or if you have on a tight pair of jeans or bend down to pick something up.
The manual states:
- Press the button to sound the panic alarm.
- Press the button again or switch the ignition on to turn it off.
- Note: The panic alarm only operates when the ignition is off.
7. Key Fob Running on Low Battery
A common cause of mysterious alarms on the Fusion is a low key fob battery. Similarly, if the fob is dirty or dusty this can also cause alarm issues.
Give the inside of your fob a clean and replace the battery to eliminate this possible cause. It’s worth spending a bit extra for a good brand of battery.
- To open your key fob, stick your prying tool into the slit or gap between the two halves of the outer casing and gently apply upward pressure to pop open the device.
- Remove the battery.
- Give the key fob a good clean to remove any dirt or fluff – a cotton swab and some rubbing alcohol should do the trick.
- Check for damage, rust or loose connection (you may need a new key fob depending on what you find).
- Be sure to insert the new battery facing the right way up.
- Assemble the outer casing of your key fob by clamping them back together.
8. Incorrectly Installed Aftermarket Alarm
An incorrectly installed or faulty aftermarket alarm system is a common cause of nuisance alarms.
Aftermarket alarms are typically far more complex than any factory-installed equipment which makes them more prone to issues.
They may also have been installed by incompetent individuals.
If you are experiencing issues with an aftermarket alarm, the best thing to do is speak with a reputable auto electrician.
“The Fusion factory alarm has no shock sensors. It sounds as though your vehicle has an aftermarket alarm system. You will need to find out what brand alarm and if there is a sensitivity adjustment. Or disconnect the system. But it would be difficult to tell you how to do that blindly over the Internet, since it is not a factory system…” – FordFusionForum.com
9. Drastic Temperature Change
We have found a handful of posts online claiming that extremely cold weather can randomly set off the Fusion’s alarm system.
While there are no technical service bulletins or confirmed reports from the manufacturer regarding this matter, it is still a factor worth looking into, especially if you keep your car parked outdoors, in the cold.
One owner on CarGurus.com mentioned the following:
“I have found that it is a sensitivity with the alarm system to the big temperature changes in the winter time because that’s the only time I have that problem. It would only go off when it would change from being really cold to warming up fast in the morning- then the alarm would go off. No problems any other time of the year.”
10. Wind and Vibration
The Ford Fusion’s alarm can be triggered by excessive wind or vibrations from larger vehicles.
To deal with the wind, make sure all doors and windows are shut tight.
As for the vibrations, try parking away from busy roads.
The alarm may also be triggered by loud noises.
11. Water Leakage
Water leaking into the latches and sensors can cause various issues including shorting out the door sensors.
The rubber seal around the edge of the door can often be a cause of leaks.
A short-term fix is to to remove the door trims and use a hairdryer to dry out any wet components.
Long term you will need to get the leak fixed.
12. Rust and Corrosion on Door and Hood Latches
Rust and corrosion can also damage the latches and switches, which may trick the sensors into detecting that a door or the front hood is open.
If your car is frequently exposed to moisture, road salt or rain, then you should routinely inspect your vehicle for any sign of rust or corrosion.
13. Damaged Wiring
Damaged electrical wiring can cause a wide range of problems, it can often be tricky to pinpoint too and you may need to have an auto electrician run some diagnostic tests with a scanner.
14. Animals Climbing On The Vehicle
If your alarm has been set off in the middle of the night, it may have been by an animal climbing on the car.
States such as Illinois, Indiana, Iowa, Texas, Wisconsin, and Carolina have large wild raccoon populations.
Have a look for footprints on the hood and the roof.
If you have a CCTV system, examine the footage. These animals usually appear during the night.
15. Not Closing Doors, Hood, or Trunk Properly
Something as simple as not properly closing the doors, hood, or trunk can cause alarm issues.
Make sure to check if you have closed every point of entry of your vehicle to avoid accidentally tripping your Fusion’s alarm.
The manual states:
If any door or the luggage compartment is open, or if the hood is open on vehicles with an anti-theft alarm or remote start, the horn will sound twice and the direction indicators will not flash.
Check for Recalls or TSBs
By entering your car’s VIN number on Ford’s recall page or the NTHSA’s Safety Issues & Recalls page you can determine whether or not there is a TSB or recall for your vehicle and if there is you’ll want to get it addressed.
A recall is issued by a vehicle manufacturer for issues that are safety-related, while a TSB covers components that may be malfunctioning but don’t compromise the safety of the vehicle.
Disconnect the Battery
Sometimes mysterious alarm problems can disappear with a simple reboot, there are no guarantees here but it’s worth a try.
Disconnect the battery for 20 seconds and this resets many of the electronics in the vehicle.
Check For Warning Messages
When the alarm occurs can you see any lights or warning messages on the instrument panel?
This can give a clue as to what’s causing the alarm e.g. ‘Hood Ajar’.
Take it to a Ford Dealership
If needed, take your Ford to the dealership.
Tell them you are NOT paying for a check on what the problem might be.
Ask them if they will check it for free.
Most dealerships and other places do quick/initial diagnosis for no money as they plan to make money for the repair of your vehicle.
If your unit is still under warranty then they should fix and resolve the issue for free.
How to Test the 12V Battery
How to Test the Battery:
- Before testing, remove the surface charge from the battery, this allows for an accurate reading.
- Simply turn on the headlights for 2 minutes then turn off.
- Set the multimeter dial to the ’20 Volts’ setting.
- Make sure the car is turned OFF.
The multimeter will have a red probe and a black probe.
- The red probe is for making contact with the positive terminal.
- The black probe is for making contact with the negative terminal.
Measure across the battery terminals.
- The meter should display a reading, if the battery is fully charged the voltage should be between 12.2 and 12.6 volts.
- Anything under 12V and the battery should be charged or replaced.