C Class 2003 Alternator / Battery warning light

[rowesa]

When I used my car recently it came up with the Alternator / Battery warning light, along with an error saying that the coolant is low. I checked the coolant and all was fine. The car started so I left it on for an hour to charge the battery.

The next day completely dead, so I called the RAC who checked the alternator and battery and said that whilst the battery only had the ability to store about 50% of the stated amps it should still be ok given that the alternator is kicking out sufficient amps.

He got the car running off his booster pack / jump leads and we took the car for a good run (30 mins), when we returned we turned the car off and messages appeared to disappear.

When we restated it really strange things happened, the headlights would not go off, the wipers ran randomly. He suggested that the SAM may be the issue.

I tried the car the next day and all was fine, I thought my luck was in. Just tried it again and doors will not even open with the fob. The car does not even recognise the fob when turning in the ignition - completely dead.

appreciate any thoughts on whether this is the battery / alternator or SAM.

Kind Regards

Steve

 

[television]

Welcome Steve,,, that RAC man should never jump start a early 203 with a flat battery, I find his remarks strange on the battery and the charging, and do not have much meaning.

Jump starting this car on a flat battery will have blown the front SAM

 

[Cole@MBS]

We see one last friday, same thing, jump started, front and rear SAM's blown!!

Costing the owners a lot of dosh!!

 

[rowesa]

Thanks for the comments. The RAC report says non start flat battery / test alternator 14.03 volts / 68 amps, may be a result of the body control unit and may just need software upgrade.

The RAC used leads with a spike protector, I assume this would protect the SAMs? If not I'll be writing to the RAC for an explanation on this practice.

I never noticed the random behavior from the wipers / lights before the RAC intervention, may be because I had not tested for this?

Cheers

Steve

 

[Alex Crow]

it does all point to a front sam issue, as has been said, but it seems it was already failing before the jump start. the rac will have used surge protection and a battery to start it (ie not a running engine), and will claim this is a safe procedure.

it is true, as has also been implied above, that jump starting the w203 can damage sam units, particularly the rear ones it seems.

 

[rowesa]

Thanks all for the comments so far.

I plan to get this into an independent at some point, however immediate issue is that the battery is flat and I cant start it.

I plan to charge the battery, appreciate the correct procedure and any pitfalls, i.e. will I need the command code or any other kind of info to reset any devices?

Kind Regards,

Steve

 

[Alex Crow]

no command code needed, best practice on this car is to remove the battery terminals before charging as it gets a bit touchy about such things.

 

[television]

If the battery is disconnected then better to cream off the possible over voltage that is enough to spike a SAM, just use a bulb or something to get the voltage back to 12.5 volts

Its worth reading this

http://forums.mercedesclub.org.uk/showthread.php?t=37364

 

[rowesa]

Thanks - when I reconnect should it be in any particular sequence.

Also I have read I may need to reset the windows - how is this done?

Kind Regards,

Steve

 

[television]

Take the key out of the ignition and have the car doors closed.

I would turn the headlamps on when reconnecting, it makes no difference as to what terminal first.
'
To re set windows and roof,, just close a window and hold the switch in the up mode for a few seconds while the key is turned to 2,,the same with the roof.

The ESP lamp will go away as you drive

 

[rowesa]

Thanks very much for the advice. If this issue does prove to be one of the SAMs, is there any guidance for DIY replacment?

I have also read on this site that the wiper / headlamp sensor is placed close to the rear view mirror, and given the random behavior of the wipers/headlamps it has been suggested that this could be at fault - welcome any thoughts on this.

Kind Regards

Steve

 

[Alex Crow]

if the wipers are in the off position they should not move at all, regardless of any rain sensor problems. the wiper motor is triggered through the front sam unit btw, as are the headlamps. diy swapping of the sam units are not possible i am afraid, they would both need coding with a star machine. but you absolutely need a proper diagnosis before buying any parts - we can only do so much over the internet.

 

[rowesa]

Hi - Just to update you all on the solution in my case. The battery was removed and tested at Halfords. It was that poor that it could not even run the test cycle, I purchased a new battery and feared that it would just be drained. I have had the new battery on for 4 days and all is well, just shows how sensitive the car is to poor voltage.

Many thanks for all the advice.

 

[monet208]

Hi
03 C180K coupe Alternator warning message - comes up every few weeks then goes off afetr 5-20 seconds.
garage says charging ok and one of diode packs could be failing. Can these be replaced or could it be brushes ?

 

[rowesa]

Change Alternator on C220 CDI 2003

Hi does anyone have any instructions on how to remove the aux belt and alternator. I want to change the IC unit in the Alternator as the charge is intermittent especially on start up.

I found this great way to check the charge - turn key to position 1 (select mileage with steering wheel controls) and then press the reset button three times this displays the battery voltage, standing and charging voltage.

Thanks

Steve

 

[Stoney Ground]

Just tried that little diagnostic trick, as we just had the water pump replaced and drive belt (is this the same as the V belt) replaced.

Since having that done, the baterry warning light has been continually on the engineer at an independant speciaist told my wife its all running fine and to leave it for a week or so to see if it goes out 'it may have got damp as its under the water pump.

The reading I get is 12.4
ESP Dynaometer test
ON
W term 15 off

Any feedback welcome