Where is the alarm module on 1998 SL500?

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IanX

New Member
Joined
Aug 12, 2017
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3
Car
1998 SL500
Hi, I'm having problems with the alarm on my 1998 SL500 R129. Once it went off when I started the engine. Another time it peeps 5 or 6 times and goes silent, other times it goes off when I unlock the car and open a door, sometimes it goes off when I just unlock using the remote, sometime it behaves!
What I'd like to know is where is the alarm unit fitted? And has anybody done any fault finding on it who can pass on any advice.
Thanks.
 
What type of remote fob do you have?
Try triggering the alarm and follow the sound to locate the alarm siren.

Dec
 
Mine a 94, in the boot above the battery. I have a feeling later cars had it behind the instrument cluster.
 
Hi Dec, it's a 3 button IR remote with fold out key (see picture), I know where the siren is (under the bonnet RHS), but I don't know where the alarm unit is.

Thanks Richard, I've got a pneumatic unit (for the door locks) above the battery, but no sign of an alarm controller. Behind the instrument cluster seems a bit of a pain. I'll have to stick my head in the footwell and look up!
 

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As an example, on a W202 the alarm control box, also referred to as the alarm brain, is located below the cluster, it’s the box with the Black cable tie wrapped around it in picture below. There is usually not enough room to accommodate it behind the cluster.

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try here… https://postimg.org/image/4waoh6y4p/


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Inside the alarm siren will look something similar to what’s below in picture

Siren%20battries.jpg


It’s unlikely that the alarm control box (brain) is at fault, it is more likely that the siren is the cause of the problem.
If it were me, I would cut open the siren by going round it with a hacksaw so as to split it open into two halves so as to examine the PCB & batteries.

Dec
 
Hi Dec, it's a 3 button IR remote with fold out key (see picture), I know where the siren is (under the bonnet RHS), but I don't know where the alarm unit is.

Thanks Richard, I've got a pneumatic unit (for the door locks) above the battery, but no sign of an alarm controller. Behind the instrument cluster seems a bit of a pain. I'll have to stick my head in the footwell and look up!

Loads changed on the facelift cars, I'm almost certain they relocated the alarm module on immobiliser key cars.

Getting the cluster out is easy enough, plenty of help online. I made a couple of hooks from an old coat hanger, remove the knee bolster and feel behind (ohh errr missus) to make sure they're located properly. Then push from the back and tug the hook, kind of wiggling it out. I doubt you'll see much from underneath.

As Dec say's though, might be worth investigating the siren 1st, notorious for giving problems.
 
Thanks Guys, I'll have a look over the weekend. Cheers, Ian
 

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