09 cls 350 cdi charging fault

[Johny]

Hi all
I was hoping someone could help with an issue I have with the charging system
I replace the battery a few weeks ago as it was flat in the morning all was ok for a while but then I noticed the head lamps dimmed when the windows were operated and also the headlights flicker on tickover I checked the charging and it can't make 13v but it doesn't drop when the lights are on there are no warning lights on the dash I can't find a wiring diagram any ware
Many thanks johny

 

[brucemillar]

Sounds like alternator or slipping belt. You should see 14v + at 2.5k revs. Measure across the battery terminals.

Sent from my iPhone using MBClub UK

 

[Johny]

Hi I'm sure it's not the belt have test the battery across the rev range it only rises a little but won't make 13v I don't think it's the altanater as it makes some charge I wondered if there was a battery control/charge unit or relay somewhere
Many thanks johny

 

[brucemillar]

Hi I'm sure it's not the belt have test the battery across the rev range it only rises a little but won't make 13v I don't think it's the altanater as it makes some charge I wondered if there was a battery control/charge unit or relay somewhere
Many thanks johny

The regulator pack is usually built into the alternator. I am not sure of your specific model. Somebody else on here would know. But of you cannot get above 13v that suggests that your alternator is not charging the battery.

 

[Johny]

Thanks any help is much appreciated
Johny

 

[Johny]

Altanator replaced yesterday still no good I think it must be a relay or control module but which one