I recently purchased an '88 300CE and have been trying to fix the most urgent issues.

One that has me stumped is the on board alarm system. Here's the story behind what's been happening.

A day or two after I had been driving the car (post purchase) I started the car and began to hear a "clicking" sound. The sound seemed to be coming from under the dash on the passenger side. The clicking sound had two separate speeds, one the same frequency of ticking as the turn signal and the other half a second slower between ticks. The sound would subside after a period of approximately 1-2 minutes (I haven't timed it specifically) and whenever the brake is depressed the clicking returns. I found out when I took it to the Mercedes dealership for a checkup that the clicking was the alarm system and that the only reason the horn and lights weren't going off was because the alarm had been "tampered with and disabled, and would probably have to be replaced" (Mercedes dealer).

I asked the man from whom I purchased the car if he had ever had problems with the alarm system before. He mentioned that a few years ago when he and his wife were driving home, the alarm system was constantly going off. He took it to the Mercedes dealer (the same I took it to) and they had no idea why it was going off, with no way of fixing it. He told them just to disable it if they couldn't figure out the issue. Odd that they told me that it had been tampered with. Of course, they didn't know it was the same car I suppose. They said the fix would be to replace all the key tumblers in the door and the ignition. I didn't see how that would help as his starter and tumblers had all been replaced at 100,000 miles. The car now has approximately 140,000 on it.

Confused and just looking for answers. Perhaps I can disable the fuse that is connected to the alarm system (or is that not even tied to a separate fuse.) The only other thing I can think of is to do what they say.

One last clue, perhaps because the previous owner's son had replaced the blaupunkt radio, which is tied into the security system, that has also been causing alarm issues?

Thanks for putting up with the long post. If you have questions because I really have no way to best describe my issue, please feel free to leave them and I'll check daily.

Thanks!

Cmarison