Ok, I'll try to keep this brief, but any help at all would be greatly appreciated....

I've been working on an 05 convertible...water leaks everywhere...gas filler, back window, etc. I removed everything from trunk, dried all water, tossed old modules (central lock and tow) all leaks are fixed and now ready for new modules.

The problem I had was lock unlock not working, alarm randomly going off, convertible top light steady flashing and won't go back.

Today, I picked up 2 used modules (locking and tow). The central locking was a little damp, but for $20 I took a chance. Took it apart made sure it was dry. Module is in perfect shape. Looks absolutely brand new.

Hooked it into car, replaced fuse 9, 25, 26. (All for central and alarm)

Success...lock, unlock worked great 3-4 times got in tried top and realized battery was about dead. Jumped it off and now...

NOTHING
Alarm goes off ...key fob won't arm, disarm, locks don't work etc. any ideas. I thought I had made my day on a $20 gamble. I find it hard to believe the module would work perfect for 4 times then stop all together.

After much research... Maybe my low battery (even after starting) is the issue. Maybe I need to fork out the $500 for a new module. Any way to reset anything or ideas that might help me solve. Thanks.

 

Cheap..free..and worth a shot.. fully charge the battery disconnect for 10-15 minutes and reconnect. Almost wonder if modules didn't by chance get confused with voltage drops and spikes per sey.

 

I agree, I am convinced MB engineered in a hidden battery monitor that is not in any of the service manual schematics or procedures that insures the battery is either new, or at 100% charge and capacity.
If not, it randomly decides to do something that is guaranteed to **** you off.

 

Here's a little for instance.. after putting LED's in all turn signal locations, It hyper flashed the hazards. It didn't with two in front.. or two in rear..or two rear and drivers front. When I did all four I got hyper flash. (I SWEAR, IT DID).. Last night when looking over the SRT 6 with Pizzaguy.. no hyper flash on hazards! Turn signals yes.. but the hazdards quit.. go fiugure..

 

Well, I put in a new battery (taken out of my spare truck) just to try it out. Same problem. What baffles me is the siren still goes off with fuse 9 in place even if the central locking module and tow module is unplugged from the car.

I left the battery unhooked for 30 min, put in the new, plugged in fuse and the siren buzzes non stop. I am going to assume that the central lock module is bad, but doesn't make sense why it would work perfect 4 times then stop responding.

I downloaded the service manual. Maybe I'll get out the voltmeter and try and confirm a bad module.

 

That sure is weird... and I don't really have an answer for you either. Except could something have gotten zapped when you jump-started the car? I've always been wary of jump starting modern cars with jumper cables. Seems like the computer parts are all too sensitive to the potential power surges and dips when doing so.

When I've had a dead battery on a vehicle at home, I've used a battery tender, plugged into a household wall circuit, to SLOWLY recharge the battery and waited at least 8 hours or so before trying to start it back up. Yeah -- I know.... not practical if you're in a hurry to be someplace when you find out your battery is dead. But much better for the battery, if it turns out it's not in need of immediate replacement, and I suspect better for the electronics.