355 alarm is driving me nuts! Please help!

So for the last couple of months the alarm has been going off for no reason. And I don’t know how it’s supposed to sound but it’s just a loud constant piercing beeping noise. Doors, rear hatch, hood shut. So I figure today is the day I go out the garage and try to find out what the issue is. I have had the battery on a trickle charge with the battery on the off position. For a week or two. So I unplug the charger and as soon as I turn the battery to the on position the alarm/beeping goes off. I try to shut if off the the fob and no luck it will not stop. I get in the car and see if starting the car will stop the alarm and the car starts right up with the alarm/beeping still blaring as loud as can be. The car is running and the alarm is still on? So what can it be.

 

Just cut the wires to the alarm speaker and silence the useless piece of ****.

 

Lol. What about pulling the fuse. I would hate cut wires. Also would doing that prevent the car from starting.


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Your car is running just fine while the alarm is blaring, why would that be different. The alarm horn is accessed with the front bumper removed so that is where you start.

 

Well removing the bumper is a little beyond my skill set. Any other way?


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Hold the button on the key fob down for a few seconds. That's how you reset/shut off a tripped alarm.

 

You shouldn't need to remove the bumper. Just remove one of the panels under the front bumper. Figuring out which one is the hard part. It's on the left hand side on my RHD car.

The siren is possibly faulty. When you arm/disarm the alarm, the immobiliser ECU sends a signal to the alarm and the memory circuits inside remember this (even with the car's battery off). Refer to other message threads on battery/siren replacement. You may find the siren's battery leaking onto the siren circuits.

 

I did I held it down for five seconds or more. Still didn’t shut off.

 

Ok I’ll try that but like I mentioned before the sound is a piercing beeping noise is this the same thing. It’s not really a siren noise. Thanks for the reply.

 

Where is the noise coming from? The front of the car? Inside the cabin?

 

It’s coming from the front of the car. Looked at some other threads, so maybe the siren battery? I have noticed (before all this happened) that the alarm light on the dash was on when I was driving the car. So I guess my question now is how to get to the siren to replace the battery or the unit itself.

 

According to the wiring diagrams, the immobiliser also triggers the car's horn. Could it be that the horn is normally so loud, the siren's odd noise isn't readily noticeable to owners?

 

The red dash vent light on while driving means the siren battery is dead.
I replaced mine awhile ago.
I don't recall how I did it, but it did not require the front bumper to come off.

 

Do you know what side it’s on or where it’s located.

 

It's been three years now.... EDIT: I did this in 2012. Man time flies!

Drivers side. Pretty sure I went in by jacking up the car and pulling the access panel that is forward of the front wheel.

I replaced it with a Corvette alarm that was a drop in replacement with a small harness.
Alarm was a Bosch 15213135

Tucked some acoustic fabric in the output portion of the horn to lower the volume (ie: stuffed a rag in the damn thing to shut it up)

 

Alarm on my 98 GTS F1 is on the Left hand side.

remove the small faring onnthat side of the bottom of the bumper gains you access but Id remove the front wheel and then the wheel well, I think its easier to reach like that.

 

Thanks for all the replies! Gonna pull the siren and see if it’s just the battery or the unit.

Thank you sir!

 

thanks Watson!

 

Here is a good thread on battery replacement. I bought a battery and removed the siren (without removing the bumper) and found that my siren does not come apart. It is working fine, so I didnt cut it open to try and access the battery.

https://www.ferrarichat.com/forum/threads/siren-battery-diy.571753/#post-145878208

 

If it is just the battery, I'm wondering how it stops the siren disarming. If siren battery power isn't available, you'd assume the main battery would take over and power all the internal circuits. I think it's more than just a battery problem, but some other damage has occurred because of battery leakage. Expect some damage as in that link that emac provided.

 

You are probably right Qavion. I am sorry, I didnt mean to suggest that the battery was the cause of the OP issues. I got a bit side tracked. Hopefully, SA Mike can get the siren removed and opened up then post what he finds.

 

Michael, there's no need to cut off the battery when you have your car hooked up to a trickle charger. Also, the alarm siren battery depends upon current from the battery to keep its battery charged. You might be able to bring your siren module back to to proper functioning order by driving your car around for a while. Use the trickle charger when your car is parked in your but don't cut off the battery.

Barry

 

Good point. In fact, if you attach the trickle charger to the engine bay battery bus bar (and nearest chassis earth) or the cigarette lighter and disable the battery using the cutoff switch, the car's battery won't charge. Both the postive and negative charger leads must be in some way attached to the positive and negative battery terminals. The battery negative is hooked up to the chassis via the battery cutoff switch.

To recharge the siren battery it must either be attached to the battery's (positive and negative) or the trickle charger's (positive and negative). The trickle charger positive will always be attached to the siren battery positive (wherever you attach it... battery, cigarette lighter*, engine bay bus bar, etc). It's the siren battery's negative (earth) which is the tricky part. The siren battery's negative lead is attached to a particular wiring splice which is attached to chassis earth in a very roundabout way.

*unless your cigarette lighter only works with the ignition on.

 

I found it necessary to replace my siren battery a few months ago. The siren is located on a left hand drive car, just ahead of the front left side marker light. As mentioned earlier, simply remove the bottom left access panel under the bumper. For better access, remove the left wheel and the panel ahead of the wheel. The siren is held to its bracket with two hex nuts. They simply need to be loosened, not removed, as they are captive; the siren will slide free of the bracket with enough wire harness length to drop from the vehicle to disconnect the connector.

Early Bosch sirens have four plugged screws that need to be removed to separate the housing for circuit board access. Later models will need to be cut open along the seam as was the case with mine. My batteries measured correct voltage, however there was not enough current capacity for the circuit to operate properly, thus my center air vent LED was luminated during drive. I replaced my batteries with a 9v NiMH battery (7.9v under load) which fit inside the siren housing.