W220 S500 not starting

[Suki]

Hi All,
My father has a s500 (w220 I believe.)
It appears that the alternator is not charging the battery, but would like to know if anyone else has had this issue. (The reason I beleive it is the alternator is because the car starts instantly when I charge the battery, and when I check battery voltage is <12 volts on a brand new one)

We connected it upto a diagnostic kit and it said voltage to circuit 87 is low.
We have the WIS CD's but can't find circuit 87. (For those of you whom are experienced, this is the alternator that is not water cooled.)

Has anyone had this? If so was it the diode pack or the alternator? Has anyone relaced a single diode? Has anyone ever tested an alternator by connecting it up to, say a drill, and then looking at the output on a scope?

Thanks in advance


Suki

 

[Chas]

It might be the alternator regulator (£46)

http://www.detali.ru/cat/oem_mb2.as...GA=722.618&CT=F&cat=66H&SID=54&SGR=026&SGN=03

It was when mine started playing up

 

[Suki]

Hi Thanks for the reply.
it seems that when I remove the bolts to remove the alternator it is sill 'locked' in place by 2 split collars (half is in the engine mount and the other half is in the alternator housing).
Any ideas how to remove this?
I have looked it WIS and it does not mention this 'modification'!
Regards
Suki

 

[television]

With the engine running the voltage should be 13.8-14volts if it is it is not the alternator

 

[Suki]

Hi Television,
I am pretty convinced that that batter is not charging..
the only problem is attempting to get the alternator out!
Now merc are saying that they can not sell me the tool!!!
btw a website people may be interested in...
http://www.service-and-parts.net/dcagportal/DCAGPortal/workshopDb.action

 

[Chas]

Hi Television,
I am pretty convinced that that batter is not charging..
the only problem is attempting to get the alternator out!
Now merc are saying that they can not sell me the tool!!!
btw a website people may be interested in...
http://www.service-and-parts.net/dcagportal/DCAGPortal/workshopDb.action

Did you check the regulator?

 

[Suki]

HI, No I have not, Are you suggesting that I can get the regulator out with out removing the alternator?
Regards
Suki
If so how!

 

[Chas]

HI, No I have not, Are you suggesting that I can get the regulator out with out removing the alternator?
Regards
Suki
If so how!

Maybe Malcolm can tell you how to check if the regulator is regulating the voltage properly ??
I would have thought you could check it in situ ?

ps what year is the car?

 

[Suki]

Hi Chas, the car is a 04 plate.
The technical way to check if it is charging is with a scope.
I can confirm that it is not charing, but I can not confirm if it is the diode pack or say the windings.
I was going to connect the alternator to a drill then connect to a scope before and after the diode pack.
Suki

 

[Chas]

Hi Chas, the car is a 04 plate.
The technical way to check if it is charging is with a scope.
I can confirm that it is not charing, but I can not confirm if it is the diode pack or say the windings.
I was going to connect the alternator to a drill then connect to a scope before and after the diode pack.
Suki

I think you should check the regulator, not the alternator.
Also you should be getting an error showing up with "low battery warning" in instrument cluster.

 

[television]

The brush pack is only held on with 2 screws.

But it is so simple, why do you need a scope, do you know what you are looking at if you had one, cant see where the thread is leading.
'
Its so simple, the car runs on the alternator not the battery, start up and if you have 13.8volt on the battery with the engine running then the alternator is fine, if not change the brush pack and try again

 

[Suki]

Ahh Malcom...
I understand what you mean....
I was using a scope as I was assuming that it was the DIODE PACK. You are referring to the BRUSH pack!!!
I shall have a look tonight!
Thanks in advance.
Suki

The reason for the scope is to see if the voltage from alternator is being converted from AC to DC!


CHAS: I did a diagnostic telling me that the voltage is low.

 

[television]

Ahh Malcom...
I understand what you mean....
I was using a scope as I was assuming that it was the DIODE PACK. You are referring to the BRUSH pack!!!
I shall have a look tonight!
Thanks in advance.
Suki

The reason for the scope is to see if the voltage from alternator is being converted from AC to DC!


CHAS: I did a diagnostic telling me that the voltage is low.

You cant access the diode pack, only the brush pack with 3 brushes that pick up from the slip rings

 

[Suki]

Hi Malcom, We managed to get the alternator out.
The brushes are fine. I think the diodes are gone. I tested the alternator before and after the diodes. Before the diodes I get ac, but after the diodes I get nothing....
I will let you know how I progress
Regards
Suki

 

[Suki]

Hi All,
I thought I would write and let people know how we resolved the alternator issue.
Basically there are some components (presumably a series of high power transistors) in the alternator brush pack.
We ordered this unit and connected it back to the car!
it worked first time.
If this happens to someone else there would be a couple of things I would check first
a) check at the battery side and see if voltage is ~13 v.
If not disconnect the alternator and see if there is a circuit between the alternator and the battery. (The reason for this is to check the fuse which is in the drivers side footwell).
If this is ok, then you will have to examine the alternator, if this is not ok you will need to check and possibly replace the fuse.
I tested the alternator by connecting it to a drill and looking at the AC directly from the coils on a scope.
Hope this helps someone else in the future!
Regards
Suki

 

[television]

Hi All,
I thought I would write and let people know how we resolved the alternator issue.
Basically there are some components (presumably a series of high power transistors) in the alternator brush pack.
We ordered this unit and connected it back to the car!
it worked first time.
If this happens to someone else there would be a couple of things I would check first
a) check at the battery side and see if voltage is ~13 v.
If not disconnect the alternator and see if there is a circuit between the alternator and the battery. (The reason for this is to check the fuse which is in the drivers side footwell).
If this is ok, then you will have to examine the alternator, if this is not ok you will need to check and possibly replace the fuse.
I tested the alternator by connecting it to a drill and looking at the AC directly from the coils on a scope.
Hope this helps someone else in the future!
Regards
Suki

Thanks for your super post and job done, thats the way things used to be

 

[BlackC55]

There was a service measure replacing this part for this exact fault

 

[duraman]

Had mine replaced at service free of charge as there was supposed to be a recall on this part, might be worth checking for other owners.