The Honda Passport is a well-rounded family SUV.
Like any other vehicle, it’s not unheard of for the alarm to go off mysteriously.
If your Passport alarm keeps going off, we are here to help…
Table of Contents
Why Does My Honda Passport Alarm Keep Going Off?
A Honda Passport alarm can be triggered by faulty door/hood switches, 12V battery issues, keyless entry/TPMS module faults, key fob issues, aftermarket alarm issues and a faulty BCM.
1. Faulty Door Switches
Faulty door switches are a very common cause of random alarms on the Passport, these switches 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.
- Speak to your dealer and ask them to run a diagnostic test to try and pinpoint the fault.
- The vehicles computer should have the data on which switch (sensor) triggered the alarm on the past few occasions.
2. Faulty Hood Switch
A faulty hood switch is a common cause of unwanted alarms on the Honda Passport.
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.
Have your dealer run a scan for the cars alarm history, it should show the trigger point and may point to the hood latch sensor being the culprit.
If you’re mechanically inclined you can buy a replacement hood switch online and fit it yourself or the easiest option is to have your dealer take a look.
On PassportForums.com here is what one owner had to say:
“In the Passport the alarm is activated by any of the doors, rear hatch or hood being opened after the alarm has been set. Ensure all your doors, hatch and hood are properly closed. If everything is well closed and the alarm is still being triggered then there are two likely culprits, one is rodents chewing cables and the other culprit may be the hood latch…”
3. Key Fob Low On Battery Or Dirty
A common cause of mysterious alarms on the Passport 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 swap 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.
Random alarm triggering can happen because the key fob is defective or low on battery.
4. Faulty Key Fob
Another reported cause of nuisance alarms on the Passport 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.
5. Weakened 12V Battery
A faulty or weakened car battery causes a variety of problems, including accidentally triggering the Passport alarm.
The best thing to do is take your Passport 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.
One owner on PassportForums.com had this to say:
“All kinds of crazy things can happen when the battery is on its last leg in today’s vehicles.”
6. Loose or Bad 12V Battery Connections
Loose or bad 12V battery connections can cause a number of problems, including triggering the alarm of your Passport.
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.
- Re-connect the battery, ensuring tight connections
7. Keyless Entry/TPMS Module Failure
A reported cause of random alarm activation in Passport models is a faulty keyless entry/TPMS module.
TPMS and keyless entry systems rely on transmitting, receiving and decoding radio waves – when they are faulty they can cause various problems including triggering the alarm.
Owners on PassportForums.com had this to say:
“The Keyless Access/TPMS Control Unit does indeed control the locking/unlocking function alongside the Multiplex Integrated Control Unit (MICU) but going by the Honda description of its trigger events in the service manual as attached below, I’m of the opinion that a failure of the unit will cause failure to respond to the fob when the lock/unlock button on the fob is pressed instead of randomly triggering itself with false unlock events.”
“The problem is with a computer box called the ‘Keyless Entry/TPMS module’ which is located behind the glove box on the passenger side of the vehicle.”
8. Faulty Body Control Module (BCM)
A faulty body control module can cause a wide range of issues including nuisance alarms.
On other Honda models (Civic, HR-V and Pilot) the BCM has been a reported cause of nuisance alarms.
- The BCM is in charge of electrical communication from different electronic systems.
- This includes the car alarm system, lock-unlock functions, climate control etc.
If you feel that your BCM is the culprit behind random alarm activation, then book an appointment with your local dealership to have it inspected.
9. Improperly Installed Aftermarket Alarm System
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.
10. 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.
In some cases, rodents may have chewed through some of the wiring.
11. 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.
Have a look for footprints on the hood and the roof.
12. Not Closing Doors, Hood or Trunk Properly
Sometimes a false alarm can be caused simply by not shutting a door properly, including the hood and trunk.
Check for Recalls or TSBs
By entering your car’s VIN number on Honda’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 Honda Dealership
If needed, take your Honda 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.