Alarm working but no lights flashing ??

[catrin2468]

Have searched everywhere for answer so hope someone can help please
Battery went flat on my ML270 52 plate was charged back up
everything working on truck except radio and alarm
When I set them alarm all the doors lock no problem but don't have the 3 flashes from indicators
The red light for the alarm flashes in the car as if alarm is set
Have set alarm and open each door separately and alarm goes off each time even sat in car set alarm and opened bonnet alarm goes off
Just don't have the 3 flashes of indicators when set get the 1 flash when I open truck
Please does anyone have an idea
Thank you for taking time to read !!!

 

[Dec]

The alarm siren, which contains the brains of the alarm system is on its way out, if it’s the origional siren then its 13 ? years old, the all give trouble at that age.

A replacement alarm siren is £100 from MB dealer & easy to fit.

Dec

 

[catrin2468]

Hi Thank you for the quick reply
Never had a problem with the alarm till car went to garage for work and they some how let battery go flat
Since they recharged the battery this problem has appeared all was working fine before

 

[Dec]

Inside the siren, over time, the rechargeable batteries begin to corrode and short-circuit and damage the circuit board, if the car battery is allowed to go flat then this sometimes hastens the demise of the siren, all the Mercedes sirens are of a similar design.

Examples… https://www.google.com/search?q=Mer...ved=0ahUKEwidh_2hlbXRAhVLBMAKHXY9AXQQ_AUIBygC

What’s up with the radio, bad reception OR no power at all? The siren might be causing that fault too.
Have you checked all fuses relating to alarm/radio/central locking.

Dec

 

[catrin2468]

Thank you for explaining it !!!
More money Lol !!
The radio is on but just reads standby its a kenwood radio and I don't have code either more money !!
Thank you very much for help hopfully going back to garage tomorrow He run battery flat he can help sort it !!(hopefully )
Is the alarm siren easy to replace ??

 

[AMGeed]

Is the alarm siren easy to replace ??

Yes its very straightforward. It sits behind either the n/s/f or o/s/f wheelarch (model dependant) liner against the bulkhead so you just need to remove the rear section of archliner.
You'll need a T25 or T30 security torx bit (cheap in Halfords) to take off the old siren (the new one is supplied with a new bolt), undo the electrical connection and replace with the new one. No coding required afterwards.

 

[Dec]

I’m not 100% sure it is the alarm that’s causing the fault but it does sound very like it, see what the garage say tomorrow.
The video below shows how it’s done on a W203.

https://www.youtube.com/watch?v=BzmpeK1TFfw


There are two things you can try today;

1… If a door is left open and then the car is locked with the remote fob… the alarm won’t go off while the door is open… the hazards should flash 2 times… instead of 3 … as a warning that a door is open, try that and see what happens.

2… Trigger the alarm by opening a door while the alarm is armed, the siren should sound for 30 seconds and the hazards should flash for 3 minutes, the alarm should then re-arm itself. Time it to see if it does indeed sound for 30 seconds and flash for 3 minutes.

I think if you go into a Mercedes dealer with the cars VIN (Vehicle Identification Number) the can give you a code for the radio, I don’t think there is a charge for this.

Dec

 

[catrin2468]

Hi
Have just tried the first one you asked me to do
Left door open locked car no hazards flashed but red alarm light came on inside car and alarm didn't go off

 

[Dec]

The blinking Red LED should come on every time the car is locked so as to show that the alarm is armed.
We learned nothing from that test then, it should have flashed the hazards 2 times.

Dec

 

[catrin2468]

Hi Again
Only thing that I have noticed different now is that
when dis arming the alarm only the passenger hazard light flashes once now drivers door hazard doesn't flash when dis armed ???

 

[Dec]

Are the hazard lights working as the should with either the ignition on or off?

Dec

 

[catrin2468]

yes all working except when I un arm the alarm then only passenger hazard light flashes once lol
All fun and games lol will see what happens tomorrow at garage
will let you now
Thank you for all your help !!
Be interesting to find out why my battery went flat has have never had problem with it and all was working before went in to garage

 

[Dec]

Might not be a faulty alarm at all, I'd be very interested to know how it goes, keep us informed.

Dec

 

[catrin2468]

Hi Dec
next chapter lol
go out to truck this morn open up using fob (never had prob with fob) Stood next to truck lock using fob the hazard lights flash 3 times on locking truck !!! Did it again stood next to truck same thing worked as normal !! Lock truck come out 5 mins later press fob central locking wont work !!! Keep pressing fob nothing Go back in wait 10 mins press fob central locking opens !!! Havent locked truck since !! Off to get new battery for fob before visiting garage will let you now !!!

 

[Dec]

The distance you are from the sensor in the door could be a factor.

If the remote is just a few inches from the sensor in the door then the IR (infrared) part of the key unlocks the car.

If you are far away, like 10 to 20 feet, the remote uses RF (radio frequency) to unlock the car, the RF signal is picked up by the same antenna that the car radio uses, in some cases, a faulty alarm might be causing the locking and radio fault.

Dec

 

[andy27168]

Hi,
Sorry to Hi-jack this thread but it is relevant and may help the O/P or the O/P or other facelift ML163 may possibly answer the question, Where is the Alarm Siren on a 163 as all genuine documentation I have looked at shows it under the bonnet adjacent to the throttle cable actuator. My friends 163 the siren does not work when the alarm is tripped so want to replace it and we cant find it even looking in the wheel arches behind the front bumper.
Whats also troubling is the Alarm Horn relay and fuse is missing from the fuse box though I am convinced these were only used when the car's horn was used as the alarm siren.
Any help appreciated as ever.

 

[catrin2468]

Hi Dec
Changed batteries in both key fobs
Central locking now works but still no 3 hazard light flash on lock from near or far away Radio working fine was in standby
All doors are working off the alarm when set and bonnet and boot when you open them alarm sounds
Found out that battery went flat at garage cause they left the truck on ramp for 2 days with bonnet open
So still none the wiser all fuse good Would there be anything on alarm were maybe the 3 flashing lights can be turned off but alarm still work
Garage says alarm siren working as should just not flashing hazards on locking

 

[Dec]

Hi,
Sorry to Hi-jack this thread but it is relevant and may help the O/P or the O/P or other facelift ML163 may possibly answer the question, Where is the Alarm Siren on a 163 as all genuine documentation I have looked at shows it under the bonnet adjacent to the throttle cable actuator. My friends 163 the siren does not work when the alarm is tripped so want to replace it and we cant find it even looking in the wheel arches behind the front bumper.
Whats also troubling is the Alarm Horn relay and fuse is missing from the fuse box though I am convinced these were only used when the car's horn was used as the alarm siren.
Any help appreciated as ever.

“underneath the wiper mech under a small metal plate” according to this thread here… http://www.mbclub.co.uk/forums/electronics/158196-alarm-siren-location-ml270-2004-a.html

Dec

 

[Dec]

Hi Dec
Changed batteries in both key fobs
Central locking now works but still no 3 hazard light flash on lock from near or far away Radio working fine was in standby
All doors are working off the alarm when set and bonnet and boot when you open them alarm sounds
Found out that battery went flat at garage cause they left the truck on ramp for 2 days with bonnet open
So still none the wiser all fuse good Would there be anything on alarm were maybe the 3 flashing lights can be turned off but alarm still work
Garage says alarm siren working as should just not flashing hazards on locking

At least its working, apart from the 3 flashes, , I know you want to get it to work as it should, leave it for a few weeks to see if any change.

Do test the siren sometime in a supermarket car park to see if it will sound for 30 seconds.
Is there any evidence that the siren was changed since the car was new?
Where is the siren located on your car, some say under the wiper mechanism and some say behind wheel arch?

Dec

 

[catrin2468]

Thank you for all your help !!!
It does sound for 30 seconds then rearms its self It is working fine except those 3 flashing hazards on setting Got a lot of people scratching there heads
Think they said mine is on passenger side under the wiper mechanism
Lets see what happens over next few weeks Battery on truck is old but working well but I am going to have a new one fitted Wonder what weird and wonderful things will raise there head then lol
once again thank you for your help and thoughts on this mystery !!