1986 W126 Security System Operation - Radio “Trigger” Circuit

[Golden80s]

Hello all,

A quick question about the function of the security system on a 1986 560SEL as it pertains to the factory Becker 754 installation and the 5-pin security connector that is also spliced into that spring-clip “trigger” -

Namely does the security system activate when ground is broken or does it activate when ground is established upon radio removal?

For example - when installing an aftermarket HU should one ground the security wire or, instead, make damn sure one doesn't?

I am certain that at some earlier point in my car's life when the security system for the radio was unplugged that the 5-pin security wire WAS grounded meaning that that is either 1) good practice or 2) that my security system has some deeper issues – i.e. not recognizing radio removal.

Right now I have it grounded w/o the alarm going off.

Thanks in advance!