C220 CDI W204 2007 Alternator Brushes
02-10-2019, 06:02 PM
#1
Member
Thread Starter
C220 CDI W204 2007 Alternator Brushes
Hi,
At rest the battery reads 13.5V and at idle or 800 RPM, the charging voltage reads only 13.8. The battery is a fairly new Varta, the original one had a life of 10 (!) years. I will have to rev it up and check if the charging voltage goes above 14V as it should do. But sooner or later the brushes will have to be changed.Do you know if that can be done while the alternator is still inside the car or not? Any tip for the purchase of the brushes? Is it easy to read off the alternator model number to order the right brushes?
So many questions, so little time!
So many questions, so little time!
12-08-2021, 03:31 PM
#2
Newbie
Alternator issue
Sorry for bumping up an old thread with no replies, but i have the same issue now. Would you happen to remember how you solved this?
Hi,
At rest the battery reads 13.5V and at idle or 800 RPM, the charging voltage reads only 13.8. The battery is a fairly new Varta, the original one had a life of 10 (!) years. I will have to rev it up and check if the charging voltage goes above 14V as it should do. But sooner or later the brushes will have to be changed.Do you know if that can be done while the alternator is still inside the car or not? Any tip for the purchase of the brushes? Is it easy to read off the alternator model number to order the right brushes?
So many questions, so little time!
So many questions, so little time!
12-08-2021, 04:45 PM
#3
Member
Thread Starter
Aliexpress sells a US$4 thingy you plug into the cigarette lighter socket and it will display charging voltage plus it gives you two USB sockets. This way I saw the voltage climb up slowly during charging and according to my manual, it is not supposed to go beyond 14.3V. Pity is, it does not display voltage at rest.
I must have panicked and worried about the condition of the brushes of this older vehicle, but so far there has been no problem with the charging. I have however, a nasty problem like some Merc owners in regards to parasitic draw, which I have to find out where it is coming from. One problem was lights coming on intermittently when the light switch was OFF, but that is fixed by setting the switch to AUTO.
I must have panicked and worried about the condition of the brushes of this older vehicle, but so far there has been no problem with the charging. I have however, a nasty problem like some Merc owners in regards to parasitic draw, which I have to find out where it is coming from. One problem was lights coming on intermittently when the light switch was OFF, but that is fixed by setting the switch to AUTO.
12-15-2021, 02:15 PM
#4
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MY'14 W212 M276 3.5NA @55kMi
VReg + SAM + ECU...
Aliexpress sells a US$4 thingy you plug into the cigarette lighter socket and it will display charging voltage plus it gives you two USB sockets. This way I saw the voltage climb up slowly during charging and according to my manual, it is not supposed to go beyond 14.3V. Pity is, it does not display voltage at rest.
I must have panicked and worried about the condition of the brushes of this older vehicle, but so far there has been no problem with the charging. I have however, a nasty problem like some Merc owners in regards to parasitic draw, which I have to find out where it is coming from. One problem was lights coming on intermittently when the light switch was OFF, but that is fixed by setting the switch to AUTO.
I must have panicked and worried about the condition of the brushes of this older vehicle, but so far there has been no problem with the charging. I have however, a nasty problem like some Merc owners in regards to parasitic draw, which I have to find out where it is coming from. One problem was lights coming on intermittently when the light switch was OFF, but that is fixed by setting the switch to AUTO.
As for your parasitic drain, the No1 suspect are the twin SAM's. These modules always remain powered ON to manage power for all other modules.
Normally SAM's go into a perfectly good low-power mode. However for a couple reasons, the software control hangs into a sloppy state after seeing too many CAN glitches.
The easiest thing to do regularly is to simply REBOOT your car by unplugging the battery for 5mn.
You should find that having a freshly booted SAM's positively influence the smoothness of engine + transmission with good timely processing.
The front SAM computer is very much like an ECU's butler. It's designed to be "fault tolerant" however SAM's latencies are very capable of messing with ECU real-time PWM processes (injection, ignition, VVT, fans, ...)
Pleasing the SAM's is another chapter, let simple reboots bring you joy.
🎄
12-15-2021, 05:16 PM
#5
Member
Thread Starter
Thanks for that, CaliBenzDriver. At the moment the battery is disconnected to stop it discharging, so a forced "rebooting" is in place unbeknown to me. Looks like a Merc stealership has tried to work on the front ECU as the plastic holding lugs were broken.
12-15-2021, 05:36 PM
#6
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MY'14 W212 M276 3.5NA @55kMi
Have you scanned your car OBD port to see which modules have trouble codes? This will give you an idea of what is going on.... SAMs do not have the monopoly to drain the battery.
Most modules are simple to repair if you can pinch them (except Headlights, ECU). ECU use a pretty rugged design, thank God ie. Bosch!
Most owners keep getting batteries replaced every 2 or 3 years, not knowing better.
12-15-2021, 05:55 PM
#7
Member
Thread Starter
Thanks again. Have a good iCarsoft scanner to check the codes. Have had the misfortune of a dead Merc with a locked steering column due to the locking motor having lost its brushes, so I had to remove the entire steering column, etc., so it the moment I am past amusement stage as I managed to end up with a 180 deg. reversed steering wheel and have to do the repair again. So the novelty of riding a quiet elegant car after many Japanese buzz boxes has become diminished.
Other faults of this 14 year old 135,000km Merc: Needs $400 new light switch as lights are intermittent on OFF, has to be left on AUTO. LH front door does not lock/unlock. Merc stealerships never changed Diesel fuel filter nor changed auto gear box oil/filter at 60,000km and 120,000km. Excuse: Owner refused service! Rubbish! Oil stank and was black.
Other faults of this 14 year old 135,000km Merc: Needs $400 new light switch as lights are intermittent on OFF, has to be left on AUTO. LH front door does not lock/unlock. Merc stealerships never changed Diesel fuel filter nor changed auto gear box oil/filter at 60,000km and 120,000km. Excuse: Owner refused service! Rubbish! Oil stank and was black.
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12-15-2021, 06:14 PM
#8
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MY'14 W212 M276 3.5NA @55kMi
crazy HL SW ... sensor fix!
I totally agree with you about the novelty amusement vs. back to back drama 
On the up side, 90% chance I have the fix for your crazy HL!
You just need to solder the loose pins inside the windshield light-rain sensor.
In and Out under 40mn, nice and easy.
The chunky light switch itself is only a logical input for the F-SAM that manages HL power relay.
On the up side, 90% chance I have the fix for your crazy HL!
You just need to solder the loose pins inside the windshield light-rain sensor.
In and Out under 40mn, nice and easy.
The chunky light switch itself is only a logical input for the F-SAM that manages HL power relay.
Last edited by CaliBenzDriver; 12-15-2021 at 06:27 PM.
