R129 alarm issues

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ivan1983

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Aug 21, 2012
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577
Location
Middlesex
Car
R129 500SL, R170 230K, 530i Touring, ZZR 600
Hi all,

I am having some issues with the alarm in my R129 and would appreciate any help on how to bypass its fuel cut off.

It's a 1997 build car with the factory fitted debagged scorpion alarm control unit GM11221MGH and siren JS1064MGB

I opened up the siren and the batteries have corroded , but as I understand it shouldn't affect the operation.

I have also opened up the control unit and the relay inside it doesn't seem to operate, I removed and tested it and it functions correctly.

The car starts fine when I bridge the fuel pump relay contacts but this is not a permanent solution and I can't seem to find a wiring diagram for the alarm.

Any ideas
 
Just as an aside, the "MBSS" (Scorpion) alarms were fitted in the UK rather than at the factory ... certainly in January 1997. This is the certificate that came with my car - note they were supposed to be serviced every 12 months!

MBSS.jpg
 
You can definitely tell that it wasn't fitted at the factory , I should have said dealer fitted! I also think it's a safe bet to say that it hasn't been serviced yearly even though the car has Mercedes service history!

I take it you have replaced the batteries in yours?
 
You can definitely tell that it wasn't fitted at the factory , I should have said dealer fitted! I also think it's a safe bet to say that it hasn't been serviced yearly even though the car has Mercedes service history!

I take it you have replaced the batteries in yours?

My car still has FMBSH from new but I doubt the alarm has ever been touched, and I'd put money on the the siren not working any more. TBH they are a pain on old cars - years ago we had a 1996 Audi and in the end resorted to leaving that unlocked because the alarm kept going off in the middle of the night and nobody could fix or even disable it!
 
I fitted a Mercedes (Scorpion) alarm to my SD1 Vitesse. It worked fine for a few years then went off without any intrusion in the middle of the night when we were in a caravan park near Thirsk. It sent the peacocks wild as I couldn’t find the keys to switch it off. It created quite a stir.
I finally disabled it using the master security key on the alarm.
 
Is that the red fob?

If so I might try using that.

Prior to this I had never used the alarm fobs just the standard Mercedes key.
 
This thing? I assume it plugs into the alarm control box somewhere under the bonnet, although I've never looked for it! 😊

Capture.JPG
 
Yes, thats the thing. I have kept that and the credit card at my parents place. For some reason I keep a set of all my spare keys there.

On mine the socket for the fob has been installed on the right pillar in the drivers footwell. There is also a corresponding red led. Apparently another location for the socket is in the glove box. It's not weather sealed at all so will be somewhere in the car near the dash area.

When I insert the black fob the led stays on for a bit and then goes off.
 
On mine the socket for the fob has been installed on the right pillar in the drivers footwell. There is also a corresponding red led. Apparently another location for the socket is in the glove box. It's not weather sealed at all so will be somewhere in the car near the dash area.

When I insert the black fob the led stays on for a bit and then goes off.

Just had a look and yes my socket is in the driver's footwell ... no LED that I can see though. Had the car for 16 years and I finally know where this thing goes :D
 
Hopefully you never need to find out any more about it!
 

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