Ford Expedition Alarm Going Off? (7 Causes & Solutions)

The Expedition is a massive people mover with modern tech features.

Like any vehicle though, it’s not uncommon for the alarm to go off randomly.

If you’re Ford Expedition alarm keeps going off, this article is here to help.

Why Does My Ford Expedition Alarm Keep Going Off?

The most common cause of the alarm going off on a Ford Expedition is linked to the interior motion sensors. Other causes are hood switch issues, low key fob battery, a faulty body control module, faulty door sensors and a low 12V battery.

If your Expedition alarm is going off when it shouldn’t then by process of elimination, it shouldn’t be too hard to find the root cause...

1. Interior Motion Sensors

A very common cause of the Ford Expedition alarm going off at random is linked to the interior motion sensors.

The idea behind these is that it lets you keep your window open – but the alarm will go off if someone reaches in your vehicle to steal something like you’re phone or iPad – the sensors are aimed at and are monitoring the four windows.

The sensors are located in the roof console, two on the left and two on the right, in a square formation – they are round/circular looking and run in line with the roof console lights.

Sometimes flies and bugs (or a mouse) might get trapped in the car or even leaves being blown in, which can be picked up by these sensors thereby triggering the alarm.

Some owners have complained that after leaving their dog in the car they’ve come back to find the alarm going off.

Give it a week of not arming the interior sensors by selecting the ‘Perimeter’ option, push ‘Ok’ to set. You will have to do this each time you turn off / exit the vehicle, and see if this stops the alarm from going off.

Note: If nothing is selected the car will default to both interior and exterior sensors every time. It is not possible to default to ‘Perimeter’.

On ExpeditionForum.com, here are a few owner’s success stories:

“Then I tried changing the alarm setting from “all sensors” to “perimeter” mode. There has been no alarm since the change.”

“I just ended up using “perimeter only” setting and that seems to do the trick.”

“I changed my alarm settings from “all” to “perimeter” only and I haven’t had a problem since.”

How to Change Alarm Settings

This will vary depending on the model year but you’ll need to locate your alarm settings on the screen.

 In Advanced Settings/Vehicle, you can select 1 of 3 choices:

  1. Perimeter
  2. All Sensors (turns on the interior sensors)
  3. Prompt every time

If you’re often leaving dogs inside, ‘Prompt Every Time’ which is the same as ‘ask on exit’ is probably the best option – as soon as you turn the car off, you can select the appropriate mode for that cycle.

Alternatively, you could cover the sensors with something like electrical tape.

2. Hood Switch Problems (Hood Ajar Indicator Switch)

Like most vehicles the Expedition utilizes a hood latch sensor which is essentially an electrical switch.

It is designed to trigger an alarm if someone tries to force open the hood, however if it is broken or clogged with dirt this can trigger the alarm.

Dirty Hood Switch

Due to the prominent location of the hood switch, it is very prone to getting dusty, dirty and grimy – the accumulation of which is enough to cause alarm issues. Corrosion and rusting of the hood switch is also very common, which can also trigger the alarm.

Give the switch a thorough clean and make sure it is completely free of dirt and debris.

Here’s what one Ford owner had to say on CarGurus.com

“My car alarm had the exact problem [going off at random]; clean or replace the hood sensor. It’s a little rubber nub. I never even knew mine was there. I cleaned it and so far so good. You could also just purchase a new one, easy to replace with a 10mm socket. I’ve replaced a door latch, hatch latch and rear hatch sensor and after almost $800 paid to the repair shop, it appears I fixed it myself.”

Faulty Hood Switch

It’s not uncommon for the hood switch to develop a fault or get damaged from the bumps of driving, from slamming the hood or from exposure to weather.

If the switch that monitors whether the hood is open or shut isn’t working then this will impact the alarm.

If you’re mechanically inclined it’s not too difficult to replace these and you can pick a new one up from autozone fairly cheaply.

If not have your Ford dealer take a look.

Here’s what a couple of Ford owners had to say:

“For those of us that had it previously [alarm going off at random] it was the hood alarm triggering it. There is a “plunger” like sensor under the hood that goes bad.”

“When my alarm kept going off it was the switch under the hood, passenger side, that was loose (guy at the body shop forgot to tighten it back down)”

3. Faulty Door Sensor

A faulty door latch sensor is a common cause of Ford Expedition alarms going off.

Similar to the hood latch sensor, your Expedition alarm monitors the doors to make sure no one is opening them.

It’s a good idea to give all door latches a clean and some lubrication with WD-40, open and close the doors to work it in.

Here’s what a few Ford owners had to say:

“Dealer hooked up the computer and said it was a couple of the door switches, so it’s scheduled for the shop next week.”

“It seems the door switch replacement was successful. Haven’t had the door ajar light come on, nor has the alarm randomly gone off since replacing the switch on Wednesday.”

“After 2 months of not sleeping because of the alarm going off, as a last ditch effort I went to the dealer and they found that one of the door ajar sensors had shorted. This is why the alarm would go off at night, the dome lights would come on and off while driving, and the doors would unlock and lock because the computer thinks the door has come ajar when nothing at all has happened in reality. The best $260 I’ve ever spent.”

If you suspect the door sensor is faulty and your car is still under warranty we recommend taking it to the dealer and having them replace it for free.

Related: Ford Expedition Tune-Up & Maintenance Costs (Complete Guide)

4. Dying 12V Battery

A dying 12V battery or a battery with low voltage can cause a slew of problems, including activating the alarm of your Expedition. This should really be the first thing you check as it’s a very common cause and it’s easy enough to check and fix.

Most 12V car batteries last about 3-4 years so it might be time for a new one.

It’s always worth cleaning the terminals first though and making sure the connections are tight and free from dirt, gunk and debris.

Tip: Clean the terminals using a toothbrush dipped in baking soda and water mixture

Failing that, the next step is to check the battery, you can do this with a multimeter.

Here’s what one Expedition owner had to say:

“Try another battery for a week and see if it doesn’t straighten out. The battery voltage needs to be well over 12.6 v to hold the relays open.
Also, clean the connections real well, double check the 10 gauge black ground leads to the radiator support. Should be <2 ohms”

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.

If you’re not confident doing this, take your car to any AutoZone who often offers free battery health checks.

5. Faulty Body Control Module

A common reason why a Ford Expedition alarm keeps going off is due to a faulty body control module.

The body control module or ‘body computer’ is the electronic control unit responsible for monitoring and controlling various systems associated with the vehicle’s body such as the alarm, immobilizers, power windows etc.

The body control module can develop corrosion on the pins or connections can become loose.

You can typically pick one up for around $700 and if you’re not mechanically inclined it’s probably best to have someone at Ford fit it for you.

Other common symptoms of a bad BCM include:

  1. Repeated battery drain
  2. Starting problems
  3. Erratic electrical functions e.g. horn, wipers, lights, lights on the dash
  4. Security and alarm system problems

6. RFI and EMR

RFI is Radio Frequency Interference and EMR is electromagnetic radiation, both of which can cause the alarm to be triggered on your Expedition.

For example, parking underneath overhead power lines will expose your car to high amounts of EMR which can interfere with the electronics on your alarm system.

If you suspect this is the cause, try parking somewhere else out the way.

Here’s some advice from some Ford owners:

“There probably is some sort of RFI being generated around where you park at work which is making your car go insane.”

“If it happens at home, but nowhere else, check your immediate neighborhood to see if one of your neighbors is a HAM radio operator… (look for big antennas, or personalized license plates with their call letters on their cars. In a nutshell Ham operators often transmit very strong signals and that can (and often does) overload poorly shielded alarms and set them off. I’ve set off many alarms in mall parking lots with my 45 watts (2m) transmitter in my car, some home setups transmit several hundred watts.”

7. Low Key Fob Battery / Faulty Key Fob

As the key fob also has controls linked with your Expedition alarm system, a faulty, damaged or malfunctioning key fob can send an incorrect signal, which may trigger the alarm. A low key fob battery can cause the alarm on your car to go off at random.

Try using your spare coded key – if the problem goes away then you know you’ll need to replace the battery in your primary key fob.

It’s also advised that you don’t carry big metal objects, electronics or a second coded key on the same keyring as your primary key fob as this can lead to problems also.

It might also be worth giving the inside of your key fob a clean as these can get filled with dirt which could be causing the alarm issue.

In summary, if you suspect your problems might be key fob related you can try the following:

  • Check and replace key fob batteries
  • Clean the key fob
  • Reset the key fob
  • Reprogram the key fob

Here’s what a couple of Ford owners had to say:

“Change the battery in the key fobs!! It stopped mine from going off.”

“I’d say the first thing to try would be to spend the $6 and get a couple of new batteries for the FOB and if it still does it then you have a bigger problem. I always try to weed out the simple problems 1st. If $6 fixes the problem then you won’t have to spend any money taking the car to the dealer to diagnose the problem.”

Related: Ford Expedition Beeping Problems? (6 Causes & Solutions)

Alternative Suggestions

Disconnect the Battery

Sometimes mysterious alarm problems can disappear with a simple reboot, there are no guarantees here but it’s worth a shot.

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 gauge cluster?

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 (run computer tests to see exactly what is triggering the alarm) for no money as they plan to make money for the repair of your vehicle.

If you’re Ford is still under warranty then they should fix and resolve the issue for free.

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.

Diagnosing Faults With a Scanner

Another possible option if you’re having alarm issues is to use an OBD2 diagnostic scanner tool, this can help narrow down what is causing the alarm.

These are fairly easy to use, you simply plug them into your car – there’s usually an OBD2 port under the steering wheel.

Once you have the scan codes you can research these online specifically for the Expedition.

There are also OBD apps available so you can connect your car straight to your smartphone (either with a cable or Bluetooth) without even needing a scanner.

Sources

https://www.ford.com/support/recalls/

https://www.fordservicecontent.com/Ford_Content/Catalog/owner_information/2021-Ford-Expedition-Owners-Manual-version-1_om_EN-US_10_2020.pdf