Uggh...this is so frustrating! Anyways, this morning I went back to Sears to have them check the battery and the charging system. I thought maybe my alternator or voltage regulator or brushes went bad so I did this before going to the car alarm installers. Sears guys were unable to diagnose the problem and told me to "see my Mercedes Benz dealer". They said they were unable to run diagnostics because the serpentine belt was loose and they were unable to tighten it. They said their charging testers were unable to do a diagnosis if certain belts are loose.

But eventhough they say my Serpentine belt is loose, why does the battery discharge when the car is off. I didn't recognize any buzzing noises either. My guess is that it really is the car alarm installers fault. By the way, I had to jump the car to get it back to Sears this morning and luckily it put back enough juice for me to bring it back to Circuit City.

So just an hour ago I took my benz back to Circuit City and complained that this Viper Alarm system is draining my brand new battery. Believe me, they heard my anger and I told them to have it totally removed and brought back to its original state when I first took it in. I just hope they haven't caused permanent damage on my electrical system. I asked for a full refund and I hope they even pay for the new battery that I had to buy. I will have to wait and see what happens.

I'll keep everyone posted once I get the car back today or however long it takes them to disassemble the car alarm, keyless entry, and remote start. After I get it back, should I go to a reliable MB dealer to have them overlook the electrical system? Would a full diagnostic check on my car be expensive? I'm worried the installers are going to do another careless job on the uninstallation.

Thanks for everyone's input so far. I've actually learned a lot more about my car by reading all the postings. I wish I had checked this site before considering an aftermarket alarm system and going to Circuit City.

Do you recommend I go to MB dealership to have an alarm system installed? I would like it done right next time around. By the way, I did ask the installer if he had worked on Mercedes before and he said he had which gave me some confidence in his work, but obviously he wasn't as skilled as I had thought. He also mentioned that DEI (the maker of the Viper alarm) didn't have a schematic for my make/model (88 300 CE), so they were basically working on their own intuition I guess. Isn't there a way to download wiring schematics?

Anyways, I'll be back again to give updates.