2003 HUMMER H2 last night natuarally 2 am in the morning ha never fails. We have been having heavy rains just tryin to give correct scenario. Stock factory Alarm starts flashing car horn alarm,, goes bonkers door switches back and fourth locking and unlocking there is no aftermarket alarm so I start it it runs perfect couple miles. like normally. so I say screw it and take cable off the neg terminal this morning connect it and its going less bonkers just intermittent security type stuff anyone run into this THX in advance for any replies Johnny, BTW I put in the garage for the night since im not sure about water in electrical stuff I did have a small leak last year however I resealed the window and has been dry since. HELP my neighbors were a little hot but its prolly cuz the don't have a HUMMER Haaa haaa fun fun fun

 

I would say your on the right track with the heavy rain seems like you got a leak somewhere if the winshield is leaking a little could be that not sure where the alarmcomponents are I'd start there When i got my wife's 08 there were water stains on the headliner and a few times water was dripping from the rear view. That was on a trip back to Ole Miss last spring my in-laws house flooded from all the rain I resealed the marker lights and hasn't done it since Alarm never went bonkers so maybe it's something under the hood but I bet somethings getting wet behind the dash good
luck

 

Do you ever get the door ajar message while driving and all doors are closed?

 

thx guys no door message I will check the plungers too we have just been swamped here in the sierras this year though.

 

I had the same issue and the horn finally stopped, and I got the alarm to stop flashing. Now the horn will not work. No blown fuses but no horn when I push the horn on the wheel or when I try and hit the panic button on the remote. I see the lights start flashing on the vehicle when I press the panic button on remote, but no sound at all and no horn.

Mine started in a large rainstorm as well, and I had water dripping from the roof area around the on-star buttons, so I feel certain the rain leaked in and created a short of some type that set off the alarm. I can't find any blown horn fuse though and all fuses check out fine. Any ideas?

 

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