Is there an immobilizer on my 1985 SEC Benz?

I am fairly certain that the SEC did not have a standard immobilizer. however in that era retro fit was quite common and the format was linked with remote locking fobs and splined key to turn off alarm immobilizer.
To turn off, the splined key was either inserted into an alarm horn under the bonnet (normally covered with a black grommet or sometines located on lower dash drivers side- again hidden under plastic cover.
Good luck and I hope you have the key

Maurice
April 2010