Alarm killed car?

[alg]

02 Explorer XLT. Alarm went off for no apparent reason twice. After the second time I removed the fuses to the horn. Today nothing works. Nothing. There is a rapid flashing of the theft light on the instrument cluster. There is a rapid audible click under the hood until I removed relay # 51 under the hood. The clicking sound and flashing light continued inside the car. I disconnected the battery cable hoping that would reset it. I have reinstalled the fuses and the relay. NO GO. Any suggestions as how to troubleshoot this? I’m 50 miles from home as this is happening. Thanks.

 

[Donystoy]

Had similar issues a few years ago. Was a voltage issue from alternator failure. Try to boost it to another vehicle. If it starts and then dies when booster cable are unhooked then might be the alternator. How old is the battery? Shorted cell in battery could also be dragging down the voltage

 

[alg]

Thanks Donystoy. I read further in this forum and found a suggestion to jump the car, which I did. It started and runs fine; stops and restarts. Now, however, the alarm has gone off about every 20 minutes. I disconnected the battery so people around me can sleep, and don’t stay awake all night devising means to murder me! Amy insights relative to this?

 

[Donystoy]

You might have an intermittent switch in one of the doors, hood switch or rear hatch. Especially if it only happens when you have the doors locked. Since the drivers door is used the most I would first check that switch. Not sure if it uses normally open or normally closed operation of switch when alarm is on but if normally closed, a break in the wiring harness between door and vehicle (very common) could be causing this. Not familiar with the relay 51 position in this but interchanging it with another identical relay is also a tool I use when trying to diagnose a problem. Hopefully the alarm electronics has not gone crazy. If this happens all the time whether the doors are locked or not I would suspect the electronics. This is all assuming that the battery is at 100%.and battery connections are all perfect.

 

[TechGuru]

Don't set the alarm for now, lock the doors manually (and don't forget the rear hatch).

Is this a factory or aftermarket alarm? If aftermarket you can usually keep those from going off by forcing the dome lights off by turning the instrument cluster dimmer all the way down until it clicks since most after market alarms use the dome light as the door trigger.

 

[alg]

You might have an intermittent switch in one of the doors, hood switch or rear hatch. Especially if it only happens when you have the doors locked. Since the drivers door is used the most I would first check that switch. Not sure if it uses normally open or normally closed operation of switch when alarm is on but if normally closed, a break in the wiring harness between door and vehicle (very common) could be causing this. Not familiar with the relay 51 position in this but interchanging it with another identical relay is also a tool I use when trying to diagnose a problem. Hopefully the alarm electronics has not gone crazy. If this happens all the time whether the doors are locked or not I would suspect the electronics. This is all assuming that the battery is at 100%.and battery connections are all perfect.

Thank you. The car has been sitting all week while I worked. I need to figure out how to check the switch, as I am not sure what you mean by that. I did try to follow the wiring to look for a break, but so far have been able to see much due to lack of ability to see much of the wiring. Could you explain how to check the switches? Thanks again.

 

[alg]

Don't set the alarm for now, lock the doors manually (and don't forget the rear hatch).

Is this a factory or aftermarket alarm? If aftermarket you can usually keep those from going off by forcing the dome lights off by turning the instrument cluster dimmer all the way down until it clicks since most after market alarms use the dome light as the door trigger.

Thank you. It is a factory alarm. The car has not been modified in any way.
How can I not set the alarm? I thought it was automatically set when the doors are locked. And the doors automatically lock when I drive. Can this be overridden? Thank you for responding.

 

[TechGuru]

Thank you. It is a factory alarm. The car has not been modified in any way.
How can I not set the alarm? I thought it was automatically set when the doors are locked. And the doors automatically lock when I drive. Can this be overridden? Thank you for responding.

As far as I am aware it's only set when you lock it with the remote.

 

[alg]

As far as I am aware it's only set when you lock it with the remote.

Thank you. I haven’t had opportunity to work on this for a while. Do you know of a way to disable the alarm altogether? Thank you.