Outside alarm one beep 2 seconds long WHY? Solved: Liftmaster Beeps Like a Prius

My 2005 Prius is 6 and a half years old and I have encountered a problem with an outside alarm that is one beep about 2 seconds long. I have checked my manual and I have found two possibilities, but, they don't seem to apply. Last week was the first time I had to go in and reset my maintenance needed reminder because my service station forgot to reset it after the last oil change. I am afraid in the severel attempts to do this I might have reset something else as well!

The outside 2 second beep occurs when the car is in my garage and the car is NOT locked. It also only occurs if I am outside of the car and have the key fob with me. It happens with either key fob near the car. If I lock the car I don't have a problem. It is as if everytime I come near the car with my key fob that it is reminding me that the car is unlocked.

Ref 2005 manual page 26 (e) - warning that the transaxle is in a position other than "P" - at this time the doors can not be locked - BUT, I can lock the doors! So I have eliminated this as being the problem.

Ref 2005 manual page 27 (g) Preventing the key from being locked in the car. BUT, I can confirm that both of my key fobs are outside of the car - one in my hand and the other sitting on a desk in my kitchen and I CAN lock the car. So, I have eliminated this as the problem.

I can't find anything else in the manual that refers to one outside beep of short duration. The only time I don't lock my car is when it is in my garage. Normally as soon as I exit the car I lock it. So, this is a recent problem that has only shown up in the last two days and I only notice it when the car is unlocked and I am outside of the car with my key fob in my purse or in my hand.

Any other possibilites I overlooked? Did I change something in my attemps to reset the maintenance needed schedule?

Springtime

 

More information:

I decided to go down to the dealer and get both Key fob batteries replaced - just in case that was the problem.

When I got home, I got out of the car, leaving the car unlocked and waited. I immediately got one outside beep of short duration (about two seconds). I tried locking the door, but, this time I waited next to the car and exactly 30 seconds later I heard the same beep. It appears locked or unlocked one outside beep is occuring every 30 seconds.

I had the 12 volt battery replaced about a year ago - so the 12v battery should be fine.

I got into the car and started it in auxilary mode and now I am getting 5 inside beeps. If I shut off the car and start in regular mode with my foot on the brake I am now getting 4 inside beeps ( which has not happened before).

I have double checked and I do not have any lights on.

I can't find anything in the manual that discusses an outside beep every 30 seconds nor can I find anything about this new problem of 5 inside beeps when starting the car in auxilary mode or 4 inside beeps starting the car in regular mode. This is a brand new problem.

I may have to take it to the dealer on Monday if no one has any ideas.

Springtime

 

I did not have my seatbelt on. So, that explains the 4 and 5 inside beeps! Just sitting in the car testing to be sure it was not in aux mode I neglected to buckle the seat belt.

So, we are back to just the outside beep that is of short duration BUT is happening exactly every thirty seconds. The beep is occuring with or without the key fob near by.

I first noticed the outside beep the day before yesterday immediately upon exiting the car. I did not realize it was beeping once every thirty seconds until I was standing next to the car for an extended period of time. I can't say if it continues when I have the car started because I usually have the window up and would not be able to here the outside beep from within the car. I may have to test it with the car on and the window down to see if it continues to beep when the car is on.

Springtime

 

Mystery solved... well almost. You will recall that I started hearing this beep a few days ago when I parked in my garage. The beep was outside of the car and was beeped every 30 seconds. I thought it might be some sort of interference caused by my garage door opener so I parked the car on the street and the sound disappeared.

Then I walked back into the garage and I heard the beep! I unplugged the garage door opener and the beep stopped. Plugged it back in and the beep started again. I have a backup battery in my garage door opener (which is now 3 1/2 years old). I suspect the beep is a warning that the backup battery needs to be replaced.

So, I can call the dealer on Monday and cancel my appointment. Now all I have to do is figure out how to replace the battery in the garage door opener.

FYI, the beep from the garage door opener sounds identical to the beep made by the Prius.

Springtime