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Discussion Starter · #1 ·
07' Envoy alarm is going off on most nights around 2:30 am. It's also gone off randomly at other times. Is there a timer or sensitivity setting for the alarm system?
 

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2002 chevy trailblazer_lt
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07' Envoy alarm is going off on most nights around 2:30 am. It's also gone off randomly at other times. Is there a timer or sensitivity setting for the alarm system?

Are we talking factory equipment here?? No aftermarket stuff?
 

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There is no timer or sensitivity adjustments. It is what it is. My first guess would be a door switch going bad or having a bad connection that makes the system think a door has opened. Maybe a heavy vehicle like a garbage truck rolls by at 02:30?? That or you have a prankster for a neighbor/friend?
 

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Discussion Starter · #5 ·
We live on a pretty quiet street, but I'll try to keep an eye out for trucks going by. How would I go about investigating a door switch?
 

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We live on a pretty quiet street, but I'll try to keep an eye out for trucks going by. How would I go about investigating a door switch?

An intermittent issue is always tough to pin down. The door switch was just the first thing that came to mind when thinking of what might set off the security system. Thinking more about the door switch now I remembered that the vehicles warning system should alert you if you are driving with a door not fully secured. Should I assume you are not getting door ajar warnings while driving?

Is the vehicle within range of the keyfob when the alarm triggers? A couple times I have sat on my keyfob in my back pocket and depressed the panic button!! Not likely at 02:30 though.
 

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Discussion Starter · #7 ·
Not getting any door warnings while driving. The key fob is hanging up in the house and it's about 40 feet away from the car so I don't think that's the issue. The only thing else that's a little different is that one of the proximity sensors in the rear bumper is hanging by it's wire. I wrapped it around the hitch to keep it out of the way. Could it be a cat rubbing against it have some effect? It went off again this morning around 6. No traffic and no wind.
 

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You have yourself a real mystery!

As far as I know there are only so many things that will set off the alarm. Door switches, liftgate switch or liftgate glass switch, a loss of power to the BCM followed by a reapplication of power.

Were I to be faced with such an issue I would use a Bluetooth OBD2 adapter and a spare android device and I would leave it set to record the data bus traffic. After shutdown and locking of the vehicle after several minutes the modules would go to sleep mode. If a door switch activated or there was a momentary power interuption to the BCM there would be a data stream to examine which would very likely shed light on what initiated the activity.

Granted this requires some basic knowledge of working with these things.

Short of that I'm about out of ideas.
 

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Not getting any door warnings while driving. The key fob is hanging up in the house and it's about 40 feet away from the car so I don't think that's the issue. The only thing else that's a little different is that one of the proximity sensors in the rear bumper is hanging by it's wire. I wrapped it around the hitch to keep it out of the way. Could it be a cat rubbing against it have some effect? It went off again this morning around 6. No traffic and no wind.
That has got to be one BIG cat.
 

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Discussion Starter · #11 ·
You have yourself a real mystery!

As far as I know there are only so many things that will set off the alarm. Door switches, liftgate switch or liftgate glass switch, a loss of power to the BCM followed by a reapplication of power.

Were I to be faced with such an issue I would use a Bluetooth OBD2 adapter and a spare android device and I would leave it set to record the data bus traffic. After shutdown and locking of the vehicle after several minutes the modules would go to sleep mode. If a door switch activated or there was a momentary power interuption to the BCM there would be a data stream to examine which would very likely shed light on what initiated the activity.

Granted this requires some basic knowledge of working with these things.

Short of that I'm about out of ideas.
Actually, I do have a reader plugged in. I'll pull it and see what it says.
 
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