2004 745LI alarm goes off in park randomly and hood open fault

Easiest way to go about it is disconnect the wire to the noise maker. U could disconnect the wire to the alarm board itself but you do not know if there are some other circuits tied into it that will be disabled when you do the disconnect. But if you do it my way there is no hassle.

Of course, when the alarm goes off you will hear nada. My only concern is that when the alarm goes off if it kills other circuits that make the car go.

If you can get a hold of a schematic you can tell what the story is and what to do.

That is an indication that the alarm has been triggered. Does the beep work when you lock or unlock the car? If it does not sound when you do that, the lights are likely the alarm triggered. Check the hood switch, which is a common problem around this age...

if its an early model, i think 2001 and below there is a sensor under the hood that is part of the security system. this sensor is more like a button that is "pressed/activated" when the hood is down and alarm set. getting to the point, these "buttons" get stuck and need to be lubed up. easy and simple. if you are standing in front of the vehicle, hood open I THINK its closer to the driverside maybe 1ft or so from the glass. should be a simple fix. or possibly the batteries in the key fob are going bad but i had the EXACT SAME issue, along with many others on my 98 528i. hope this helps, Tim

The alarm tripping is often caused by a bad door or hood switch. Since the hood switch is always exposed to water and corrosion, that one usually goes bad first. Check that out. And no, you can't disable it.

I would first check the hood switch. They are plastic and tend to break or come loose. It is located near one of the cabin filter housings, I can not remember which one. It has a small rod that sticks up about 1/2 inch and has a two pin connector. Just disconnect it. Good luck.

hi bayan,

There are numerous inputs that are monitored for BMW anti theft deterrent system. All the door locks, interior sensor, hood switch, and inclination sensor can cause the alarm to set off. I would recommend making sure all your door locks are working correctly. Next I would check under the hood and make sure the hood switch is not broken or out of adjustment. I think usually the switch can be located on the plastic cowling in the vicinity near the driver side strut tower. When you find the hood switch, you can just unplug it for testing purposes. Leave it unplugged for a while and see if you still have a problem. If nothing seems apparent you can always have the system scanned to see what faults are stored in the control unit's memory.

when the hood is "open"you cannot set the alarm so it will go off as it thinks someone is trying to steal it.make sure both catches are operating correctly,a bmw dealer will (should)do the job for nothing(goodwill)my wife always asks nicely......ours is a 1987 3 series coupe...with full dealer history.

Hi , you can lock your car without activating the allarm by using the key to lock your car manually ( not the remote ) , the most common alarm fault on this car is the hood switch, if you change this buy one for a bmw Z4 model which is slightly longer and garrentees a contact when the hood is closed, hope this helps regards mark

I had a similar problem, 2003 530i, but only while the alarm was active. The culprit was a bad hood switch that was making intermitent connection.

check the hood switch and all door switches that is normal problem