The Acura RDX is a fun-to-drive, handsomely styled luxury SUV.
Like any other vehicle, the RDX is not immune from nuisance alarms.
If your RDX alarm keeps going off at random, continue reading this article…
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Why Does My Acura RDX Alarm Keep Going Off?
An Acura RDX nuisance alarm is most commonly caused by a faulty hood switch. Other causes include keyless access unit issues, faulty door switches, 12V battery issues, key fob issues, not closing doors properly, aftermarket equipment and damaged wiring.
1. Faulty Hood Switch
A faulty hood switch is one of the leading causes of unwanted alarms on the Acura RDX.
The switch is designed to detect whether the hood is open or shut and it 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.
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.
Here’s what RDX owners on the forum acurazine.com had to say:
“I saw a few YouTube videos where the hood latch sensor was faulty and caused the alarm to trigger randomly day or night. I’ve had this happen all of a sudden on our 2017 RDX, three times last night and twice today.”
“It has not happened since I unplugged the hood latch sensor. From what I observed it is a terrible design the way they have the switch setup. If you want to replace the part to correct it or just disconnect it is your choice. Personally I don’t see the need to have security under the hood as you would have to destroy it to get in there anyways. I’m going to leave mine the way it is.”
“I disconnected the hood latch sensor. This stopped the alarm. However, it stops it because the alarm system won’t arm because it thinks the hood is open. Same would happen if you tried to arm the system with a door open. So, with this plug unplugged, you have no security for the entire car. For some folks like us who live in the sticks, that may be OK.”
2. Keyless Access Unit Issues
On RDX models from 2013 to 2018 the keyless access unit was known to be problematic, a symptom of which was the alarm going off.
- If you suspect this is the case then you can take your RDX to the dealer who will run a diagnostic scan to determine what set the alarm off on the last few occasions.
- If it’s the ignition input triggering the alarm, the fix is to replace the unit.
- There’s an internal component that is shorting out and making the unit think someone is pressing the button to turn the car on.
- Other symptoms include headlights turning on randomly when the car is off or the gauges turning on.
Here’s what owners had to say on the Acura Subreddit:
“Needs to be diagnosed but most likely it’s the keyless access unit. It’s a pretty common issue on this year’s RDX (even though it’s the same unit from 13-18). They are also on backorder.
“I just had the same exact issue on my 2017 RDX. The alarm kept going off in the middle of the night so I would leave the car unlocked until I took it to the dealer. A new battery didn’t solve the issue either. They ran a diagnostic and found that the keyless access unit had shorted. It was replaced and so far, the alarm hasn’t gone off. It’s been less than a week so only time will tell if that was what was causing the issue.”
3. Malfunctioning Door Switches
Faulty door switches are another common cause of random alarms on the RDX, similar to the hood switch, 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.
If you suspect the alarm is linked to the door switch, ask your dealer to run a diagnostic test to try and pinpoint the fault.
4. Key Fob Issues
A faulty key fob can cause all kinds of issues, including accidentally triggering the RDX alarm. If the fob is dirty, damaged or low on battery, the alarm can be triggered at random (the most common reason is usually a flat key fob battery).
For the sake of a few dollars it’s worth replacing the battery in your fob(s), and it’s also worth spending a bit extra for a good brand of battery.
Whilst you have the fob open to change the battery, give the inside a good clean.
Dirt buildup and dust can cause issues with the electronics.
- 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.
5. Drained 12V Battery
A faulty or weakened car battery causes a variety of problems, including accidentally triggering the RDX alarm.
The best thing to do is take your RDX 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.
Here’s what one owner on acurazine.com had to say:
“You mentioned the dealership checking the doors. Did they mention checking the battery or other electronic components? Car could be brand new, but the battery may not be. Could be old when installed or even faulty.”
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 RDX.
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. Improperly 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.
8. Water Leakage
Water leaking into the vehicle can wreak havoc on the electronics, including setting the alarm off at random.
One owner on acurazine.com posted the following:
“my wife’s previous 2012 RDX had this issue, and it was related to the roof rack install. I guess the dealer didn’t use any sealer or filler to stop water from leaking through the roof rack mounting holes. So when it rains, water would get into the car and come into contact with some wires and cause the alarm to go off.”
9. 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.
10. 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.
11. 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.
Be sure to give all doors a good, firm shut.
Check for Recalls or TSBs
By entering your car’s VIN number on Acura’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 Acura Dealership
If needed, take your Acura 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.