TheRodsC240

Having issues with my 04 C240...in past few days, several warning lights have popped up:

Battery/Alternator visit workshop
ESP Light
ABS Light

When my wife was driving home from work tonight, car completely shut down on her and she couldn't get out of the car. I tried jumping the car and it wont turn over. I'm thinking it's the alternator, but any other thoughts? Any easy fixes I can do myself?

Any help is appreciated...

contact148

how old is the battery?

you can easily change the alternator yourself

if you run the car with a bad battery you will strain and eventually ruin the alternator


and a bad alternator can wreck a good battery.....

many auto parts places will test both for free

ammar_rage

i agree with contat148 except for the 'easily change' part...my *** still hurts from taking that thing out. anyhow tell me how long have u been having these symptoms for.. did you get these msgs before then they went away even with in a day..cuz this cud indicate an intermittently working alterntor...or did it just shut down..oem batteries have an amazingly long life like 7+ years. more than alternator itself its the VR that goes bad on these things. If you cud determine if its the battery or the alternator then the fix wud be easy.

contact148

the 240 was easy everything from above

Silver C

Changing the alternator doesn't *look* hard, well I have never changed it myself, but looking at where it is, looks pretty accessible to me.

Carsy

Diagnose the problem first. Put a multi meter across the battery terminals when the engine is at idle & slightly above say 1800rpm & see what voltage the battery is being charged . Should be around 14 V .

mrinsatiable

I had a c240 2002..not start on me for a few weeks. first i checked the 52 fuse..which was breaking. each time i started it would have to be replaced then i finally changed the fuse 52 which is the starter fuse from 20amp to 40 amp which worked for a while but finally it wouldn't start at all.

No every once in a few days the car would start normally. I ran a diagnostic on the battery and it read 11v...when the engine runs it was 14v

the suggested voltage for the battery is 12v and when running 15v

does that mean my battery is dying? would this have to deal with the original starter fuse #52 breaking and me replacing it with the 40amp fuse instead?

TheRodsC240

Just happened over the weekend and car shut down yesterday. I am being told by the shop at this point, the problem they are finding is a crank shaft sensor, make sense?

drtyjrzy

Mercedes put a 20 amp fuse in there because it should never draw more than that. if you put a 40 amp in there the system that was in place to save it from burning up is no longer going to work. what may have been a loose connection could now be a burned up piece of equipment.
I would replace the battery, put a 20 amp fuse back in slot 52 and tighten all connections on your starter and alternator.

ammar_rage

Its easy to narrow down on the problem with the process of elimination. Like others have suggested u should start with the battery first, check the volts on it and even if it is 10V , the car will start! now lets say u see around 12V on your battery that means u battery is fine, prolly u alternator is fine too!

If your battery voltage is over 10V (though it shud start even below 10v) and you can start the car then u can quickly check the voltage again and if you see 14+ v then it means u alternator is fine too unless its working intermittently that was the case with me. anyhow, if your battery voltage is fine and you cant start the car then its NOT the battery or the alterntor!

BTW yo can check the battery voltage on the screen. Take your key out, put the key back in, navigate to the main screen where it shows the mileage, then hit the reset button 3 times u will be in dyno mode, navigate into dyno mode to see the battery voltage.

ammar_rage

Abt the crank shaft sensor, I am not too sure if it wud prevent the vehicle from starting..reason is..my CEL wud come on with the malfunctioning crank shaft sensor code but the car wud start and run, prolly not as smoothly. Maybe some of the more knowledgeable guys can comment on this. I ended replacing it for like 70$ here in Canada, it is much cheaper in the US.

mrinsatiable

Now thinking about it I don't think its the battery. As the car does start with the 40amp fuse in starter position #52 located in the SAM-F.

I understand the problems i'm asking for by doing this dangerous thing. But what I'd like to know is...what is causing the starter fuse #52 from consistently blowing? *to me the clues are telling me I have a short somewhere.*

Even if i clean up the connections from the starter and alternator it still blows the #52 20amp fuse.

Could I have a faulty SAM-F?

Carsy

To blow a 20 amp fuse you must have a large fault to earth somewhere. I would check visually whether any insulation is damaged ( rubbed through)on the wiring from the battery to the starter motor. I wonder whether the starter motor has a fault.
Sounds as if advice is required from a good auto electrician. He should have an ampmeter to check on the current drawn & the knowledge on where to look for the fault.
Good luck..

bensitto

It probably is the crankshaft sensor. I had similar problems with my w203 C320 and replaced it myself. There is a DIY on it somewhere but it's a mid to advanced level project. It's pretty tight, if you have big arms it's going to be tough!

MB's batteries are known to break down too. I went through several, the cells break off and short each other on the inside. If you ever have to replace your battery I recommend the Optima Red Top Batteries. They are the BEST and way lighter.
http://www.optimabatteries.com/optim...dtop/index.php

Alternator change is not too hard if you ever need to do that. I had to replace one of those too on my C320 back in the day. A couple bolts from the bottom and a couple from the top.

Mercedesnovice

Sorry, I cant figure out where to start a post so I'm starting here:

2001 c240 ignition issue. Started after charging battery while battery cables still connected to vehicle. Vehicle will start and run fine until I turn off the vehicle and remove the key. When I re-insert key, car doesn't recognize key and won't allow me to unlock ignition. If left over night, battery is completely drained. when battery disconnected and recharged the car starts ok. If I disconnect and reconnect battery car starts fine. Also, if I remove and reinsert ignition fuse the car will start. I hear a relay click when removing and re-installing ignition fuse, which makes me think a relay contact might be sticking and seizing until the battery is drained. I don't see any electrical items being powered when the key is removed, so I'm not certain of what is draining the battery. Any idea what is causing this?

Mercedesnovice

I forgot to add, I don't know why I have to disconnect and reconnect the battery, or remove and reinsert ignition fuse to allow the car to recognize the key which allows the car to start