"med" imobiliser fault

[LVT]

Hi, does anyone have any knowledge of "med" imobilisers.
I have a 1995 E610 fitted with one, consisting of a flashing red led and a square into which a square "key" is inserted then removed
to start the engine.
The problem started when the led failed but the engine started as usual after insertion of the square key.
I replaced the led but now it remains on constantly so I replaced that one with a flashing one but that flashes continually, usually the light goes out once the engine starts.
The engine starts and runs whether the light is connected or not.
Any ideas?

 

[Swifter]

Sounds like you didn’t use the exact same led ?
Just a guess

 

[pappajohn]

Have you tried starting WITHOUT dabbing the square recess with the square key.
It may be the immobiliser had failed 'open' and isn't protecting at all.

 

[LVT]

Yes I have tried everything from tracing all the wires, cleaning the earth connections. It maybe that it needs a specific led to function properly but with no markings on the dud one and not being able to find any trace of MED apart from a defunct email address in Italy I think I will disconnect the led function.
The imobiliser its self works as it should it's just the led that's the problem!

 

[pappajohn]

If, as you say, everything but the led works I too would remove the led.
It's only an indication as to if its on or off.