Q: 2012 toyota highlander limited: Alarm often goes off without reason, even when I am in the car with the keys.

asked by on January 12, 2018

The car's alarm often goes off often without reason. For example, sometimes I would get in the car with the keys, and just before turning on the car, the alarm would go off and I have to hit the panic button to stop it. Other times, I would have the car parked in the garage at home with the doors unlocked, and when I try to open the door the alarm would go off, unless I have the key with me. This means, even when at home with the car safely parked in my locked garage, I have to carry the key with me even if I just want to pick up something from the car. I took the car to the Toyota dealership, and apparently they did not see anything wrong and did not do much to try to find out. One technician there speculated that it could be a faulty "after-market" alarm system (I bought the car used...). Please help. Thanks.

My car has 60000 miles.
My car has an automatic transmission.

Load test the vehicle battery. Sometimes when a battery is on the verge of failure, the resulting voltage drop "fools" the vehicle alarm system as this voltage drop is interpreted by the computer as tampering. If the battery passes the load test but only marginally (be sure to get the specific test results and compare to new battery specs) replace the battery outright. Apart from this, there is a diagnostic decision tree in the factory service manual that covers these sorts of failures. A mechanic has to go through the decision tree, line by line, to pinpoint the fault. If the issue is not the battery, the recommended service to diagnose and resolve this is an electrical circuit/component diagnostic. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $65/hr

What others are asking

Currently 165 65 R14 tires are mounted on my car. Can I get 165 70 R14 tires? What is the difference between the two?

The 165 on the tire size means how wide is the tread across the tire. The 65 is the side wall size to the tire and how much the tire is considered a low profile tire or a high profile...

I'm smelling gas after I drive everytime

I did not seem to find any technical bulletins for this issue. I would first recommend not driving the vehicle until you have the system checked to see what kind of fuel leak or vapor leak you are having. If...

When I am in park my car starts to over heat but as soon as I take it out of park it starts to cool? When this happens it also ma

If the engine temperature drops once you are moving that is due to increased air flow through the radiator and also the speed, and hence output, of the water pump increases with engine speed which also tends to reduce coolant...

My 2006 Dodge Charger failed emissions twice. The first time for MIL Command status and second time for KOER Result

The underlying fault depends on exactly which codes have been stored by your vehicle's OBD-II system. Those codes can be downloaded using a hand-held scanner but then each code has to be separately diagnosed, that is parts have to be...

Key not starting car

Another key could be used to see if the lock cylinder will turn completely. Chances are either the lock cylinder itself or the lock cylinder housing is at fault. The may both need to be replaced to restore ignition operation....

I need to adjust my headlights.

There are two types of headlamps available on your car - Halogen and HID. If you have HID, they are auto-leveling. I'm going to assume you have halogen. The only adjustment on your type of headlight is up and...

OBD-II failed for smog check

Unfortunately without more information as to why your Toyota Corolla did not pass the emissions test, it is difficult to determine the cause for the failed smog check. Provided that the ODB2 port itself has power and is allowing the...

How do I shift between 2H, 4H, and 4L?

The different gears are designed to help you navigate uneven terrain. There are a variety of gears for you to choose from so you find the one that best suits your needs. To shift between 2H, 4H, and 4L. ...

My JEEP GC is coolant temp is high and I changed the themorstat

Hello, thank you for writing in. While that is a little higher than we would like to see, it is not overwhelmingly hot for the engine. Once it hits 260, you must cut off power to the vehicle. Anything over...

Related articles

2012 Hyundai Sonata vs. 2012 Hyundai Elantra: Which One Should I Buy?
Mid-size sedans are a large category. These vehicles are well suited for either a large commuter car that is not going to get quite commuter car statistics as far as gas mileage or a smaller sedan option. Think of mid-size...
A Buyer’s Guide to the 2012 Audi A5
For For drivers who want a comfortable ride, expert handling and luxurious amenities, the 2012 Audi A5 will certainly fit the bill. Designed for performance and to deliver a gorgeous look, this model offers an array of options and features...
A Buyer’s Guide to the 2012 BMW 5-Series
BMW BMW has built a reputation for refined engineering, powerful performance and excellent fit and function. That’s exactly what you’ll find with the 2012 BMW 5-Series sedans. Composed and powerful, they provide a range of price points, features and capabilities...