Not certain for 172, but for 171 it is in battery compartment on the fender side.

 

I've read that battery failure in the siren is one of the most common causes of false alarm triggering. Does my 2014 SLK 250 have a siren? If so, I cannot find it.
The car is left hand drive - Have looked behind the front passenger side tire wheel well - not there. Have looked under the windshield plastic trim at the base of the windshield - not there.
Has anyone been through the anti-theft system on an R172?

 

I've read that battery failure in the siren is one of the most common causes of false alarm triggering. Does my 2014 SLK 250 have a siren? If so, I cannot find it.
The car is left hand drive - Have looked behind the front passenger side tire wheel well - not there. Have looked under the windshield plastic trim at the base of the windshield - not there.
Has anyone been through the anti-theft system on an R172?

Did you look inside the battery compartment?

 

Thank you Avel Du,
I did look in the battery compartment and even pulled the battery out, thinking it might be under the battery - but no siren. Starting to think my vehicle may not have one - perhaps removed by previous owner.

 

That is where I was expecting it to be.

So, time to call a friend (or two)

R172 alarm location please:
@Trev5 @MartinatMersea @Col @VII7

 

On some models it is inside the wheel arch liner. Not aware of this with SLKs though.

 

My Siren has gone off a few times, but not come across where it is located....

Have You done a Diag check to see if the Tow Away Module is faulty? (Error Code: U114000)

Thread on the subject: Tow away and movement sensor malfunction

 

https://www.ljcaesar.com/2017/05/mercedes-w211-e-class-w219-cls-alarm-siren-replacement/

 

Part number seems to be A2138201101 for the siren. item number 60 in the picture.

 

That looks wheel arch methinks.

Link in post 9 may help.

 

Thank you all. I looked behind the plastic on the passenger's side wheel well (not there) & will look behind the driver's side wheel soon and post again once completed.

Trev5, regarding the diag check - Can you tell me the best way to do the diag check? Would this be a dealer scan, or can I buy a device that will give me Error Codes? I'm ok using devices/computers and error codes. Is there a preferred device reader and will it provide the alarm input codes (more than informing me the alarm went off, but more precisely, what triggered the alarm?) Obviously, your error message indicates that this level of detail is available.

 

I have a iCarsoft Diag tool which reads error codes, but won't give what caused the alarm to go off...

The stored error I posted above indicates the tow alarm module in the centre arm rest lid is faulty.
As I still have MB warranty remaining on My R172, I left the error for them to look at:
Otherwise I would have cleared the error and seem whether it returns...

 

Ok thank you Trev5.

I'm also wondering about using the Key FOB to lock my car. Should the 2014 SLK250 have a siren chirp when locked? Mine does nothing more that lock the doors - no other noise (no horn beep, no siren chirp, no anti-theft noise).

Does anyone know of a code reader that would show the alarm inputs so I could see which sensor is triggering the alarm? Would a MB dealer be able to tell which sensor is triggering?

 

The chirp when the car is locked can be turned on and off in the car settings.

 

Ok, well...I understand better now, but not sure I solved anything.

Took the glove box out to check the micro-switch for the alarm. The micro switch tested good.

Disconnected everything and now I have a code on the dash because I disconnected the airbag (perhaps a mistake). NEED HELP....Can someone tell me how to clear this dash message (currently shows something about needing service- I believe due to disconnecting the airbag)?

Micro-switch is ok, but I did find that the cover on the the door to the glove box is separating from the glove box door panel. This vinyl/rubber like material was putting slight pressure on the glove box housing and MAY be the culprit that is forcing the micro-switch to activate (simulating the door opening, ever so slightly). That would be an easy fix if that is the case.... More testing to be done here.

One other item...I was able to go into the dash programming and turn on the "chirp"; which on my car is a short horn beep. (thanks DavidD) Wondering if that horn is what I'm look for and not the siren. Does anyone know if the horn that makes the abbreviated beep when you lock the car with the FOB, has a battery in it and could this be the culprit that is triggering the false alarms?

 

and other great settings if one has the m4cars SmartTop

What is this SmartTOP all the members keep talking about?

A new member asked me so I wrote this primer. Tired of holding that inside vario roof button for 22 seconds (20 - 26 depending on model)? Tired of standing outside your car with your keyfob/smartkey pointed at your door handle for 22 seconds looking like an idiot while the roof cycles? Watch...

www.slkworld.com

One-Touch power convertible top
"One-Touch" convertible top operation allows your top to open or close automatically.
Open/Close the top while driving
Never have to stop again for your top: Open/Close your top while driving
(CLK 40km/h, SLK/SL 60km/h).
Top convenience mode
Turning the ignition on or off does not interrupt convertible top operation.
Remote control of convertible top
Open/Close your convertible top using the original factory remote control key / key fob.
Separate window control
Raise and lower the windows separately by remote without activating the top.
Window positions
Window positions (up/down) after top opening programmable.
Full RF Range
Top and window operation possible from the full distance (uncapped RF range of the factory key fob).
Comfort window open/close
One-Touch opening/closing of all windows via quick double tap on the top switch.
Full Rear Window control
Raise rear windows with top down.
Keyless top control*
One-touch top operation via keyless door handle.
*Keyless entry option required.
Hazard Signals
Optionally the blinkers are activated while top is operated from the remote.
Home Light
Remotely activate the front and tail lights.
Automatic door locks
Set power locks to automatically lock and unlock the doors when you drive.
Chirp-signal function
Short audible signals when locking and/or unlocking the car.
Comfort Wipers
After using the sprayer, activates the wipers 1x or 2x after short delay.
Mirror Park Assist (SLK)
This feature can automatically dip down the passenger mirror in reverse gear.
Lock Running Car
Lock and unlock the running car by remote (Keyless Required).
Full text setup in car display
Configure functions of the module to meet your personal preferences via our full text setup menu.
Passive Mode
Turn the module off with a quick key sequence when unaltered factory operation is desired.
Valet Mode
Lock the top in the closed position with a quick key sequence when needed.
Reversible plug-in installation
Remove any time allowing sale or return of a leased vehicle in its original condition.
Plug-n-Play Wiring harness
Custom designed plug-in-between wiring harness for extremely simple and quick installation included.
USB Port for easy setup / updates
This module can be configured and updated using any Mac or PC.
Remote Control - Open and close your convertible top using the original factory remote control key/key fob up to 300 feet away. Uses RF (radio frequency) NOT IR (infrared radiation) energy

among others.

 

If you asking does the horn have it's own battery, then yes.
On older cars the battery goes bad and corrodes the internal electrics.
7 years is a bit soon. Do you disconnect the battery often? I ask because the horn battery is only there in case the circuit is interrupted.

 

That's good to hear that I might not have an issue with the horn battery. Thanks Avel Du.

When I unplugged the air bag to remove the glove box, I caused a code to be sent to the computer and now my dash shows this airbag code: "Front Right Malfunction Service Required" each time I start the car. Any ideas on how to clear this?
I've read that I might need an OBD reader to reset it? But, I also read that it may clear itself after a while?

 

Pretty sure airbag needs to be SDS, but wait for the experts.

 

As above, I think that one can only be reset with SDS, so will need a dealer, independent Merc service or someone with SDS to reset it.

 

As I understand it (not an expert) anything security, or air bags (probably seat belts?) are SDS only.

 

OK thank you - - is "SDS" same as (or similar to) OBD Reader? I see that ICARSOFT makes one - will start researching....About $100-$150 U.S.

 

Actually, you may be better with Vediamo. (remember, I am not an expert)
@VII7 will know for sure.

Star Diagnose Vediamo Coding-USE AT OWN RISK

NO post/links to pirated s/w permitted

www.slkworld.com

 

SDS - Star Diagnostic system. Dealer level diagnostics, Can be had for about £500 of our English pounds or a few more of your American dollars I believe.
@i860 @Dave2302

 

For his car is way cheaper to own a sds @£180

 

Taking a couple days off from troubleshooting and testing. Driving the SLK through the Adirondack Mountains up to Lake Placid, NY today - beautiful day, hope that it will be top down the whole trip.

 

For an airbag reset some third party diagnostics are able to do it.
Xentry or Vediamo would work as well.

Sent from my SM-G781U using Tapatalk

 

One way to eliminate the Tow Away module "A2319052600" in the Arm Rest from the false alarms, is to try disabling it?

(My Face Lift R172 lights for a lot less than 5 seconds..!!)

 

Update on the alarm system falsely going off - earlier, I removed the glove box to test the anti-theft micro switch - it tested ok - on (closed) when it clicked, off (open) on the return. When I reinstalled the glove box, I noticed that when I slightly pushed on the glove box door. I could hear the switch activating and deactivating with an ever so slight push. I also noticed that the face of the glove box was delaminating from the black plastic shell of the door. I used some 3M double sided tape (the strongest & best they offer) to secure it (so far so good). I also added a small rubber bumper to the inside of the door were it contacts the anti-theft micro switch in order to more fully depress the switch when the glove box door is closed. My theory is that the delaminated glove box door cover was putting enough pressure on the dash to push the glove box door open very slightly. this force came from thermo-cycling during the heat of the day. Still not sure that the problem is in the rear view mirror, but have over 60 hours of no false alarms and have now begun testing it in more vigorous ambient conditions (heat, cold, wind, etc.). Fingers crossed!