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Discussion Starter #1
I've got a 2006 MDX that last week had an issue with the alarm going off intermittently. Unfortunately, we were away and the neighbours say the alarm went off and on for two days straight. Of course this has to happen on the rare instance that we're on vacation and can't do anything about it.

When I got home, the alarm was not going off, and neighbours assumed the battery had just exhausted itself and died. I unlocked the car, key in the ignition, and the car started up fine... no dash warnings, no check engine light. I drove around a bit.... no issues. That night, the car was locked and sure enough at 5:30 am the alarm goes off.

Enough about the background. I scoured the internet looking for something. I did read one thread that suggested to change the battery, others for door latches, hood switch, etc. There's heavy condensation in the mornings now so I thought that might be a contributor.

Since I had never changed the battery, going on 5 years ownership, I decided to just replace the battery. Plus, there was a LOT of acid buildup on the battery posts. I have no idea how old the battery was in there. Anyways..... since replacement, no alarms. I can't be 100% sure the suspect battery was causing my alarm to go off, but I'm now on day 5 without any erratic alarm behaviour. ( I still sleep with a key in my hand.. just in case)
 

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Discussion Starter #2
Well.......just when I thought I had this problem solved 6 weeks ago:mad::mad:

6 weeks ago, I had intermittent alarm issues whereby the alarm would periodically go off randomly and also stop randomly. I replaced the battery (perhaps overdue anyways). The issue had gone away.... until last night. 2am... car alarm going off. Great. Neighbours are real impressed I'm sure.

Anyways, I think I've got a fix that is adequate for the immediate term. I think I've managed to disable the alarm. I found a post about jumpering the hood switch. I have no idea if there is a problem or not with the hood switch. But I can say that since I disconnected the connection, and then put a small piece of wire in place, when I click to lock the car, I don't get the tiny beep (after the second press), and also I don't get blinking led in the driver side door to indicate the alarm is armed.

I'm fairly certain the alarm won't sound, because after all, it's currently not getting armed. I don't know for certain though. And I can still lock the door.

I'm curious though why this works. The car now thinks the hood is open when closing that hood switch circuit? So when the hood is actually closed, the switch opens up (it's a normally open switch).

Would all this indicate I've got an intermittently faulty hood switch?
 

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No, jumpering the hood switch just makes the system think the hood is open, and then the system won't arm.

Are you by chance having any issues where one of the doors won't lock or unlock when using the power door locks?
 

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Shop manual mentions following conditions cause alarm when security system is set (security light flashing):

1) Ignition switch turned to On
2) Door or tailgate is forced open
3) Door is unlocked w/o using key or remote transmitter
4) Hood is opened
5) Audio unit, Nav display, DVD player, or rear controller and screen is disconnected.
6) Panic mode is activated.

It goes on to explain that switches; hood, doors, tailgate can become misadjusted and cause a false alarm. Temperature changes were explained as one cause. This happens overnight when temps drop and may be at root of your problem.

You can also fool the switch to think it's always open (switch disconnected from harness w/ no wire jumper). If this temporarily resolves the problem a new switch (hood, door, tailgate) should resolve the intermittent. It might be worth a try to clean switch and lube w/ WD40 or other switch lube.

good luck
 

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Sounds like it might be a good idea to set the alarm, and then yank on the doors, the hatch and the hood to see if one of 'em is set at a hair-trigger. Sounds like it almost has to be one of those, where the change in temperature can be just enough to change the sensor's state.
 
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