Ok, so I took out Fuse 64. And it turns out that the problem resolved itself, no more erroneous errors. The moment I put Fuse 64 back in, the problems resumed. So it definitely is something in the Radio that could causing the problem, hence why I've mentioned that the prerequisite to the problem is the Audio with the Dashes as well as the Telephone with the Dashes, appearing on the instrument cluster for the steering controls.

So I have two new questions for you guys:

1. What problem is the radio having that is causing it to send faulty information to the CANBUS resulting in total malfunction of all 3 SAMS?
2. Why does the Battery / Alternator light briefly come on and shut off during the problems?


Please post your thoughts and ideas below:

I would have to further drive the car and test drive it tomorrow without Fuse 64 to see if the problem will happen again.

I still have a hunch that it could be the Alternator and Voltage regulator that is too weak to support the heavily powerful Radio. The Radio does draw 40A as someone mentioned earlier. So maybe the Alternator and Voltage Regulator simply cannot supply the power demanded by the Radio so the Radio goes crazy, when it doesn't recieve the right amount of power and in turn screws up the CANBUS and the car's computer systems go awry. Now the CD Changer has been gone for months as well in fact its been dead since late March and April, which is the time I reported these problems here on MBWorld, perhaps the faulty CD Changer is to blame too. So now here is a third question:

3. Could the Dead CD Changer be the cause?

Because this all began to occur when the CD Changer stopped working. And interestingly enough, I wasn't able to find the fuses for the CD Changer. As for Fuses 24 and 26, on the Driver's Side Fuse Box, they were empty, the only thing I saw was a 30A but that wasn't in the 26 or 24.

So now that the Radio seems to be causing the issues, the Radio for the most part works, its as if the Radio isn't recieving the right amount of voltage, so it corrupts everything else in the car. Annonymous mouse said that he saw an older post regarding the Radio causing this same issue, I wish I could find that post to verify it. Apparently the solution was changing the Radio altogether.

Again I'd have to drive the car tomorrow to see if the problem persists, I live by my radio and music and to have to sacrifice it is terrible. That truly is ridiculous and it sucks! ..

 

So I have two new questions for you guys:

1. What problem is the radio having that is causing it to send faulty information to the CANBUS resulting in total malfunction of all 3 SAMS? Could be earth fault causing low voltage.
2. Why does the Battery / Alternator light briefly come on and shut off during the problems? Could be earth fault causing low voltage in entire system.

3. Could the Dead CD Changer be the cause? Possible. Try to physically isolate it electrically ( disconnect wiring) to find out.The CD is item 46 in wiring diagram supplied by fuse 64.

I suggest that you are running a risk of doing damage to your electrical system with a problem like this. Best to have it sorted out asap.

 

I find it hard to believe that this is caused by the radio other than the power it draws. I would isolate the CD changer.

I still think that this is an unstable voltage/current issue & would have the alternator & regulator checked out properly. And all major grounding points.

 

I forgot to mention that upon removing Fuse 64, the Dynamometer reads 14.2 - 14.5 Volts when idle. That is a little higher than before.

I'll try isolating the CD Changer to see what happens. Could be the CD Changer that has the earth fault.

 

Ok, so here's an update. So for those who have been following this thread, we all know that when the Radio is enabled (Fuse 64 is Connected) the problems start to occur.

So today I went to Advance Auto Parts to get a new 10 A Fuse 64, to place in the Front SAM. I wanted to perhaps get a new 10A fuse to see if it was the culprit, clearly it wasn't, they let me try a new 10A fuse and there was no difference. Bummer, So the fuse was fine. A friend of mine who works there did a few tests for me and here is what was tested:

First of all he had one of those error scanner things and placed it in the reader, and it did not detect anything. This was while the Fuse 64 was connected and the errors were showing on the Instrument Cluster.

Please note that The following tests described below were done WITHOUT Fuse 64 in Place therefore the Radio was disabled, thus the car was error free and no malfunctions were displayed on the Instrument Cluster, except for the remnant SRS Visit Workshop, which we all know has to be reset by SDS.

So then he proceeded to test the Battery, Cranking, Alternator and Drain.

BATTERY TEST
----------------



The results show that the Battery is GOOD. The Voltage read 12.65 V, and measured 987 CCA. Temperature was 114°F as well, not like thats really important...

STARTER TEST / ALTERNATOR TEST (CHARGING SYSTEM)
----------------------------------------------------------



The Starter and the Alternator both seem to be working fine at the moment. Remember this was all done without Fuse 64 in the Front SAM. So i'm not sure if having the Radio Fuse 64 (enabling the radio) in the Front SAM would make a difference in any of thse results...

Anyway, the Cranking is Normal (revving the engine). The Voltage Read 11.33V during the revving, with amps at 29.6A. This was done for about 1.43 Seconds. As for the Alternator, that seems to be fine as well based on the diagram shown. The voltages remained steady without the load and at the load. Which is about 14.2 - 14.0 which is what I saw last night. Ok so smooth sailing right?, Well not really, there is still one more test to go...


DRAIN TEST
------------
NOW here is something interesting to note: The DRAIN Test, which tests to see if there is anything draining the battery while the car is off. That test was a total failure. And here's why:



Based on that screenshot, whilst the car is off and there is NOTHING running, there was a 1.43AMP drain. Which means that whenever the car is off and the key is removed something is draining upwards of 1.43 Amps from the battery. And keep in mind that this is WITHOUT Fuse 64 in the Front SAM.

My friend suggested that it could be something in the center console of the car perhaps some kind of raw wiring that is causing a short circuit in the vehicle or perhaps even completing. He suggests that the Car should be using around 0.1A - 0.2A while its off and not 1.4 Amps. So we are getting somewhere, and I think we're getting close to solving this mystery.

So to summarize everything, here is a list of all things "electrical" wrong with the car as we speak:

CD CHANGER IS "PARTIALLY" DEAD
The reason why I say partially, is because the magazine can eject, but the Radio doesn't detect the CDs, nor does the changer change the CDs. I actually did not mention the CD Changer at all until now during the post, lol perhaps this could very well be the culprit. The CD Changer is totally dead when Fuse 64 is removed. Carsy, I couldn't find anything else connected to the CD changer. I think you mentioned Fuse 24/26 those fuses were empty. The "Sound" fuse in the diagram was also empty as well..

RADIO, WHEN ENABLED CAUSES CANBUS AND SAM PROBLEMS
The radio when enabled, causes problems with the car's computer system, causing the Front SAM to Fail, and then the Rear SAM then Fails also follows. (Lots of errors showing up on screen, display malfunction, SRS, Tele-Aid, No Blinkers, Audio and Tel with Dashes, No Wipers, no sunroof, rear sunshade doesn't work, no climate control, no heated seats, no blower, etc..)

PASSENGER ELECTRONIC SEAT ADJUSTMENT HASN'T WORKED IN TWO YEARS..
This was something that I planned to fix, but I haven't gotten to it, but the passenger seat, the electrical portion has been dead for over two years now. (adjustment of seat height and back height) I took it in for service, just when the warranty expired, and apparently whenever they put a new 30A fuse in the Rear SAM the fuse would immediately blow. Anyway I never bothered fixing it because I rarely drive the car with anyone else in it..

So thats pretty much it, man I feel like this thread is becoming a new blog for me now, lol.

Now I did schedule a service appointment with my local "stealership" again, because the service advisor told me to bring the car in the moment the car starts acting up again. I would bring the car in again, but the thing is that I'm still unsure of what is causing the problem.

WHAT THE PROBLEM COULD BE:

I personally do not think its the RADIO because the radio turns on and it works. The problem as I've said is intermittent, up until yesterday. Its been permanent, so the only remedy is to remove the Fuse and disable the radio. Now the CD Changer is another thing, the Radio when operating normally, does not detect the changer. Yet the Changer can eject the magazine, but it doesn't read the CDs, so maybe the Changer could be the problem too.

I'm also thinking that the Voltage Regulator on the Alternator could be faulty because why is the car using upwards of 1.4 Amps when its off? What in the world could be draining and using all that power?

So my next logical guess is that its probably some loose or defective wiring somewhere in the interior of the Car. Now I've checked all the wiring in the front hood, and engine compartment, and I did not notice anything. The HIDs are wired fine, (they've been on for over a year with no issues). I've already ruled them out anyway..

So I'm not sure if I should bring it to the dealership, or to an indy.. I'm lost, but I need this problem fixed and put behind me so that I can work on the mechanical regular maitenance of the car..

Now that we know that the battery is being drained, it lead me to this post by Hackman from 2004:

https://mbworld.org/forums/mercedes-...g-battery.html

He has a 2001 C240, with the Command System. The post mentions that the CD Changers could cause issues with the CANBUS as well, so maybe physically disconnecting that CD Changer would be the next course of action to take. I'm gonna try doing that tomorrow to see if there are any changes.

Here's My Rant:

Based on my research, This is a common problem for a lot of the Pre-Facelifted W203s. How could Mercedes Benz manufacter such a nice reliable car, but fail miserably with its electronic systems? This is so ridiculous, and it sucks because the CPO Warranty that I have is expired, it has been since 2008.

Any New Suggestions?

 

I have noticed in other threads that the W203 electrics are very sensitive to low battery volts.

With a power drain of about 1.5 amps over 24 hours would take 36 amp hours from your battery therefore lowering the voltage if the cars was idling .

What you need to do is to find which circuit is draining the battery. Put your mates ampmeter gear on & pull each fuse in turn until you find which circuit is at fault. It's a matter of elimination. Thats is what an auto electrician would do.

 

Could it be the short in the seat circuit causing the battery drain?

 

If you haven't already, disconnect the 4 wire power plug going to the module under the seat. It's not being used anyway. Also, be aware that there are some electrical functions that continue for X minutes after you turn off the car, or even just open the door. Like the little fan in the overhead console and outside courtesy lights (if enabled) or just the key being in port. Some pointers: if they are the correct value fuses are either good (closed), or bad (open = blown). The only reason to "pull" fuses is to see if they are blown or to isolate circuits. The 'voltage regulator' only controls the battery charging from the alternator and doesn't regulate current throughout the car. If pulling fuse 64 solves the errors then you are on the right track. I'm assuming you do not have Command. First disconnect (remove power) from the CD changer and see if that helps.

 

The fuse for the seat is blown though so there is no power at all being supplied to the seat. So I think I could rule the seat out.

 

So with the results shown above, is it safe to completely rule out the alternator / volyage regulator as suspects to the problem? The car has about 79000 miles on it and I've seen many posts with users withb Alternators giving problems as low as 25K...

 

Where is the CD Changer Power Connector? I haven't found any fuses directly related to the changer so I guess its part of the same Circuit. It makes sense that it would be considering that I do not have the Command System in the car.

Now as for the amp, it could be that I didn't wait "long" enough before testing the drain because the drain was tested right after the car was shut off. So that could be a false error or reading due to something functioning in the car like the blower or convenience lighting and etc..

I still do not believe that there would be anything draining the battery because I've had the battery in the car for about two years. And it seems to be fine. The battery was installed by Roadside Assistance in 2009.

 

I suspect you did not wait long enough for the CANBUS to go to sleep or you would be suffering flat batteries.

 

If I remember correctly, there is just one screw in the glove box to a bracket holding in the changer. Remove it and pull out the changer and the power wire and fibre optics line will stay connected and follow it out. I'm not sure if you need to terminate the FO line, unplug it at the radio, or it's OK to just let it be.

 

Yeah the drain test was actually done right after, there was no time that was waited in between the tests so the CANBUS probably was still active, plus i don't have any issues with the Battery or anything of that nature, because the car sometimes is left idle for about 2 - 3 days and starts fine. So it could be because I did not wait long enough..

I'm starting to come to the conclusion that the Radio is defective and is the source of the fault. After all of these weeks of trial and error, removing Fuse 64, was the key to determining the problem. And i'm gonna now rule out the Battery and the Alternator. I've examined all of the wires that are exposed, and found nothing unusual, the dealer also did this as well, and they even did a water test, they couldn't find anything unsual niether. I've also unplugged the passenger seat from the seat module, since its not working anyway and the fuse is blown... Thats the next thing I have to work on fixing, figuring out why the seat keeps blowing the fuse, but thats for another day..

CD CHANGER IS PROBABLY NOT THE SOURCE...

I've disconnected the CD Changer from the Radio and no difference. I still get the array of errors (Display Malfunction, and etc). The reason I say "probably" is because I don't know if the changer is also bad as well, I haven't used it in so long because I've been using an FM transmitter for so long, lol with my iPod. But anyway I think I'm in need of a new radio.

This is all interesting because:

On the second page of this thread, Annonymousmouse mentioned that he knew someone who had the same problem and changing the Radio was the solution. I don't know why and how the Radio went bad, i guess from 10 years of use, its a normal thing. But anyway the Radio would actually be the least costly option to check first, considering that they are not as expensive on eBay at least, lol. (Dealer is asking $700-900 for the regular stock radio) The CD Changer Works, as the magazine ejects, but the Changer doesn't accept the CDs or reads it, I guess that could be because the Radio isn't sending the signal to the changer to load the discs, hence why the Radio could be defective right there.

Whats interesting though is that the Radio does work, but its just faulty.

So Now What?
Well first of all I have to find a way to remove that radio. Which I am gonna do, I found the Audio-10 site, now anyone know where I can get a good radio that also supports iPod and MP3 Auxilliary Inputs as well as retaining the Steering Controls or do I have to stick to the stock Radio? I did see one with a CD player instead of a tape player that goes in front of the car.

Now from what I've been reading, removing and changing the radio is no easy task, the dealer is asking about $1,000 to do the job, which is not an option for me, especially since I've already lost $400 for nothing..

Anyone know any good Radios that will plug and play in a 2002 C240?

Also I need second opinions as well, lol is it safe to say that the Radio is bad?

 

Changing the radio is a 15 minute job. Pull out ashtray so you can get your fingers behind the center console trim around the radio and just pull it out. A couple of screws mount the radio. I would first check out the wiring going to the radio by pulling it out, pulling/moving the wires, and mounting it again. It could be a wire is shorting someplace and simple movement might get it clear. Yea, sounds like the radio and If it comes down to needing one go ebay.

 

Yeah thats the only option I might have mleskovar, Since the Stealership's parts center is asking an inexplicable $1700 for a brand new stock radio. I was fuming. I mean, for God's sake, a brand new command system can be found on eBay for a fraction of this. That is just pure insanity in its own right, beyond my understanding. Anyway I'm certainly not dumping all of that money for an old tape radio that is obsolete.

So I'll be checking eBay, but before I spend anything, I spent 7 dollars on a couple of 30A fuses to fix the passenger seat, along with a 3 bucks for a T20 long screw driver. I hope its something as simple as a loose wire or something.. Who knows, maybe some insect got in there and chewed the wire, lol. Anyway I'll post updates. The car is out of warranty so I have nothing to lose at this point, (except doing more damage). I'm actually really worried about doing this.

I was looking only apparently there is a CD version of the Becker Audio 10, only problem is that they don't sell it here, and the price is certainly better, than the ridiculous 1700 that the stealership is asking for.

Imagine if I had checked the car in to do that? It would've been easilly 2000+ dollars to fix.

Anyway apparenty the parts cashier told me that there is a guy there who knows Mercedes Radios from top to bottom and told me to come talk to him on Tuesday apparently he does, some car radio work on the side.

I'm really hoping its the Radio and Annonymousmouse's hunch was right. at this point, I'm honestly sick, tired and pretty much spent on this CANBUS problem.

I had planned to do so many things with the car this summer, especially since its nearling the 80000 mile mark, such as getting some new tires and rims, changing the passenger side lights etc and doing some cosmetic work to embrace the 80K milestone, which I'll probably obtain sometime this August..

Anyway I'm gonna attempt to remove the radio and try to move the wires around to see what happens.

 

The seat motors are a common fail item. If it's blowing fuses disconnect the motors and see if it still blows fuses and hook the motors back up one by one until you find the cuprit.

 

Yeah apparently there is a solution to this problem on BenzWorld, they were saying that I could splice two wires together in the four pin connector. (Connecting the Black Wire with the Red Wire) or something like that to disable the power to the seat whilst the car is off or something like that, if it blows the fuse again, I may just have to do that.

 

That's for a different problem. That fixes the seat module draining the battery.

 

Send the Radio to Becker for repair.

 

Oh ok, so no point in doing that then... So to add more to the problem, I have to figure out why the fuse keeps being blown, but anyway thats for another topic, maybe i'll continue this topic with the seat next, but first the radio has to be corrected. I guess I can do what Glynn suggested and send the radio to Becker for repair.

Here is another interesting note this was actually taken directly from the Becker Audio Manual that Mercedes Benz supplied:

The Radio is connected to the CANBUS network, hence why all of these malfunctions are occuring when the Radio is enabled. I'm about 95% sure that I believe I've hit the jackpot, and finally discovered this problem. The manual also talks about a code that has to be re-entered upon removing the radio. My car did not come with a Radio Code. So I'm worried that this may be an issue in the future when I'm putting the Radio back.

Anyway I explored the Becker Website turns out they have a couple of options, I have the option of swapping the radio out for another one, repairing it, or even doing an upgrade repair, in which they fix whatever is wrong with the radio and they update the radio so that it works with an Auxilliary Input such as an iPod or MP3 Player which would work through the Tape Setting. It is something I'm certainly considering, so that I can finally eliminate the need of an FM Transmitter and get the clearest sound possible.

The site mentioned that two keys can be obtained to make the removal of the radio easier. I'm not sure if these keys are for the W202s (The First Gen C-Class) because those radios were easier to remove, it seems that the ones on the W203 (01 - 04) require the removal of the vents though, but then again I'm not sure, I would much rather use keys to remove them easilly than to risk damaging my center console by taking it all apart...

 

The Problem In Action:

http://www.youtube.com/watch?v=IMn2aVWzgBg

The above is the video of the problems when they were occuring, on Monday.

 

To make sure I understand this correctly.... Radio off, problem appears when ignition is turned on, then disappears when car starts. If radio is then turned on while the car is running the problem reappears. Right?

 

The CANbus is actually a serial port that allows communication between the consumers and the SAM's. It appears that the radio HU is clamping the signals causing a variety of errors because no other consumers can talk when the signals are clamped.

Send the head unit to repair or exchange, but first look at the price of a new to you unit at a salvage yard. $ 50 to $ 100 might be easier.

Look into the seat modules. In your vintage they have a habit of staying awake long after the sandman has told them to sleep. Does not seem to be connected to your problems, but it would be nice to have working seat motors in case a horizontal mombo opportunity arises.

 

Yes the problem occurs when the ignition is on in the car regardless of whether the radio is on or not. The car is on though. And it makes sense for this to occur because when the car is on, that's when the CANBUS network is actively monitoring other components. So if the Radio is faulty it doesn't communicate well with the bus and it results in a crash. (The Display Malfunction and the Array of Errors) So long as the Fuse is in the SAM the problem would occur. It was temporary, but on Monday the problem became permanent and since then I've been driving without a radio. Although I'm 90% sure it is the radio, what in the Radio could cause it to crash the C240's computer system?