F355 alarm siren battery

My 355 is an early RHD 1995 car, it does not have an LED on the middle air vent? But I do have a key with a fob alarm button, I’ve replaced the battery in the key and it lights but nothing from the car so I use the key to manually open the central locking.


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1995 cars are Motronic 2.7 and didn't come with the immobilizer and siren. Sell your fob on eBay.

I've got these fobs for my 1995 F355 Challenge...


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The key on top is illuminated. You might have that key too.

 

Haha yes, I looked at the newly downloaded workshop manuals and noticed there are alarm switches on the door A pillars, I checked and mine didn’t have them either, then the penny dropped, the key battery was an entry light to stop owners missing the door lock in the middle of the night, an old feature of the day
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The illuminated key was high-tech in 1995.

 

If you have interior overhead lights and door lights, you will have door pillar switches. Look again.

 

After reading the article it was still not clear to me where exactly the siren is located. I have now found out myself and documented it for those who are concerned as I was.

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The early version siren, that has 2 screws for easy separation is part number 180996 and is valid up thru chassis assembly number 30998. After that, is part number 177148 and needs to be cut open for access.

Most threads seem to have information on the later style which takes 2 batteries that are soldered to the board. I have the early style which has a single NiCad battery with 2 leads and plugs into the board. Battery is Varta 7.2V 250mAh part number 6/V280RT. Does anyone know where to get this battery?

 

If it looks like this (V250H):

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You can get it at https://www.batterystore.com/varta-6-v250h-7-2v-250mah-ni-mh-battery-55625306060/. See if they provide dimensions. You can do a bit of further search on this website if the dimensions are not the same as V280RT.

 

yes, it does look "like" that. But don't I want to stay with NiCad?

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Eveready NiMH 9v, actually measures 7.8v under load. I've been using it in my alarm siren for 2 years now. Less than $10.00 and fits in the alarm siren case.
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Problem solved!! Installed your suggested battery along with a 9v battery clip connector which fit nicely under the circuit board. Siren and dash LED work as they should.

My old battery was split open and acid had made a mess of the circuit board, Did my best to clean it up with vinegar and Q-tips, and wasn't sure a battery replacement was going to solve my problem. But its all in the rear view mirror.......Thanks, Mike.

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Looking at the photos in post #31... Do left hand hand drive cars have the windscreen washer bottle on the right side of the car? My RHD washer bottle sits behind the siren where the horns are on that car.

 

^^^^^My US version LHD car has the washer bottle on the left side of the car, and the siren was just forward of the reservoir. Also, my horns are on the right side. Post 31 shows the horns behind the alarm siren.

 

Same on my right hand drive car. Maybe it's a 2.7/5.2 thing?

 

Wow, great news, glad to hear it! Nice work!

 

Ni-MH are a kind of improved version of the older Ni-Cd batteries. They are completely interchangeable as they both have the same charging requirements (characteristics). Ni-MH are believed to suffer less from the charging-discharging memory effect.

 

Does anyone know if there's a way to remove the siren part of the alarm while leaving the driveblock part of it working? I have a 993 and there is no alarm siren or chirping noise, but if someone breaks into the car or tries to take it, the alarm goes off (via the horn) and the engine can't be started because of the immobilizer. I really can't stand the loud chirping every time I lock or unlock the car, it's totally unnecessary. It'd be great to just remove the siren but I assume that would make the rest of the system inoperable. Maybe I'll just duct tape over the siren or something to reduce the db's.

 

Just disconnect the speaker wires inside the siren. The horn is activated by a different pin on the Immobiliser ECU. If you also don't want the horn, just cut the black-yellow wire going into the forward luggage compartment relay panel (plug I pin 2). Not the purple-black.

Some of the aftermarket GM/Corvette sirens don't actually trigger the chirps, but I don't know how you'd figure out which is which.

 

"Gobble" would be the person to ask about the sirens.

Regarding the horn, there's also a pin you could push out of a plug near the footwell relay panel.

Plug 41025 (pin 17) should have a black-yellow wire:

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It won't interfere with normal horn operation.

 

Thank

Thank you -- great to hear. What's the role of the horn? Does it go off if the alarm is triggered?

 

Now you've got me thinking. I haven't triggered my alarm for many years. I just assumed most of the noise came from the horn. The wiring to the horn is shown in some of my paper wiring diagrams, but not all. Perhaps there are variations between countries. Having said that, sometimes you have to piece together diagrams from various years to get the full picture. Some diagrams don't even show sirens, which can't be true.

 

I just unplugged the siren and stored it in a box in the garage where I keep miscellaneous 355 parts....cycled the fob and locks and fired up the car. Seems to be no problem removing that component. Really great to be able to lock and unlock the car without the hey-look-at-me chirp. Thank you for the tip.

 

You removed the whole siren? Doesn't that put the LED on permanently?

 

I haven't had a chance to drive it yet, will tomorrow. So far it behaves normally when locked/armed, with the LED flashing once every few seconds. But won't be surprising if it stays lit while driving, in which case I'm going to unplug the light. The alarm setup on this car is pretty anachronistic and high-maintenance and I'm not exactly leaving this car parked on the street all night where I'm worried about it being stolen. Happy to be rid of the whole thing so long as it's easily reversible.

 

I think I'm just going to leave the battery dead and put matte vinyl over the led...