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Discussion Starter #1
Hi,
My son bought a 2004 c230 that has been having problems since day one. His battery died. We pulled the battery out and took it to napa to have it tested and they said it was dead and we got a new battery. We installed the new battery and it died the next day. We had the battery charged and then had it and the alternator tested and both are showing to be fine. We went through and made sure that all the lights were off, recharged the battery and it lasted about 2 days and it was dead. Each time the battery dies overnight while the car is not running. We did a drain test and found 4 fuses that are drawing while the car is off:

F57 under hood (Steering position sensor, ecm, ignition switch control module); F31 driver side(20 A ignition switch control module); F8 in trunk (7.5A Aerial signal amplifier, alarm system horn/ graident sensor); F9 in trunk (25A sunroof control module).

When we first hook up the multimeter it shows around .84 but we let it sit on there for about 15 seconds and it drops to .40. Each of the fuses drain about .08-.10.
Also not sure if it is related or not but his AC blower motor is not working but all of the AC components seem to work.
Any help would be appreciated.
 

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Coupe/Convertible Forums Moderator
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Listen carefully to the overhead control panel to see if you hear a fan running after shutting off the engine, removing the key, and opening and closing the driver's door. Of so, that's your problem. It's a fan on the thermistor in that panel. It should shut down, but sometimes doesn't and will drain the battery.
 

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Discussion Starter #3
So I had a chance to check it finally and I did not hear the fan running. I was checking the car today and while it was running, it was only running at 13 volts according to the dash. I am really beginning to wonder if this problem is related to either the alternator even though they tested it or the voltage regulator. any thoughts?
 

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13v is a bit low. You should see 14v. It can take several minutes for the regulator to stabilize after starting.
 
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