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Security System Weirdness - Please enlighten me

10K views 5 replies 5 participants last post by  mybabybenz  
#1 ·
I took my 2003 SLK 230 (35K miles) to the gym yesterday. Got back to the car an hour later and my key fob wouldn’t unlock the door. No flashes, no audible response from the car, nothing. So I unlocked the door manually with the key. The door unlocked, but it triggered the alarm. I couldn’t cancel the alarm by pressing buttons on the key fob. Putting the key in the ignition and turning it didn’t help.

Eventually the alarm stopped, but the car was essentially disabled. The engine wouldn’t turn over; various lights on the dash were illuminated; the dash display showed “Error”; and I couldn’t even open the center console to retrieve my wallet or cell phone.

I thought maybe the battery in my key fob was dead, even though it worked fine an hour earlier, so I walked 2 miles home to get my other key. My wife drove me back, and the second key was equally ineffective.

So I did what the manual said and called 1-800-FOR-MERC. I got bounced around a couple of times and ended up with someone who sounded knowledgeable. He told me it sounded like a key recognition error. Either that or, based on an intermittent soft clicking noise I heard behind the dash, a failed pump that was having trouble with water that might have collected in my spare tire well.

I then called my Mercedes-trained, non-dealer mechanic. He said it sounded like the security module which only the dealer could fix.

So I called the dealer to let them know I was having the car towed to them and asked their service guy what he thought. He thought the key recognition issue was most likely. I asked if there was any way I could get my stuff out of the locked center console before getting it towed. He was a bit condescening in assuring me that unless there was a visible key hole on top of the console, it wasn’t locked, because (based on working for MB since 1986) SLK 230 consoles don’t lock. Right.

I called AAA for a tow. When the truck arrived I noticed that my door lock was in the down position. This surprised me because I had been unable to manually lock it earlier. I pulled out the key and pressed the unlock button on the fob. The door unlocked. I put the key in the ignition and the engine cranked right up.

The tow truck driver speculated that someone had bumped the car while I was in the gym, triggering the security alarm, and setting my problems in motion. It eventually worked, he said, because of a timer in the security system. That almost sounds reasonable to me except that I can’t imagine a security system designed so that a key-bearing owner couldn’t use the car it’s designed to protect.

Does this experience make sense to anyone? Was there something I could have done to get driving sooner? (FWIW, the tow truck driver said that if I had put my key in the door, turned it, and then removed it 3 times, it would have reset the system. Can that be right?)
 
#2 ·
Seems like your PSE pump "got a little shower". It's located in the trunk on the right side. You need to remove spare wheel to get access to it. PSE is responsible for alarm and central locking. It's possible that it has some corrosion on it. It happens quite often that side drains get clogged and water gets inside and somehow gets onto the PSE. Corrosion of terminal causes short that can trigger the alarm. Perhaps that's why your key wasn't recognized. You definitely need to inspect the PSE. Here's a good DIY thread:
PSE - Removal, Refit and Check - Mercedes-Benz Forum
When start error usually happens, you can disconnect battery for a couple minutes and it should clear the memory. :wink:
 
#5 ·
I had this very thing happen recently, and posted about it here.
http://www.slkworld.com/slk-r170-general-discussion/179570-tow-alarm-reset-issue.html
Never did find out what the cause was or why it didn't display Start Error after being towed to the dealer.
I've been driving it regularly the past few weeks since and so far it hasn't happened again.
Be sure to post if you learn anything new as my confidence in my car's reliability is rather shaken :S
 
#6 ·
My '99 is at the dealer now for this problem. I don't tend to lock my car at night but last Monday morning I came out and was about to toss my briefcase into the trunk and noticed that the alarm was on. I didn't think to much about it at first but inserting the key and turning it several times didn't turn the alarm flashing light off. I tried the door and it kept on blinking. The trunk was unlocked and so was the door. Having never had this problem before, I pushed the trunk button and the alarm went off, no way to turn it off. So, I thought perhaps putting the key in and giving it a crank would reset the system. Nope! It engaged the immobilizer and the car would crank, even tried to start a couple times. I too ended up calling AAA. The dealer has had it for two days and asked today if I could bring my second key by for them to check the ignition switch?
 
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