Hi all - am a newbie here at mercedesshop, so pleased to meet y'all (and please be gentle!! ). I tried posting this in the general tech section but haven't had any luck, thought I'd give it a go here.

I'm looking for any ideas/thoughts as to why the charge light in a 220SEb (with a 4.5L) remains on although battery charge is good? Have just replaced the alternator and it seems to be working just fine...it's holding a steady charge at revs (14.1V), and maintaining charge at idle. Any suggestions or questions?

The charge light is controlled by the voltage regulator...is yours an integral unit (part of the alternator) or external? If it is external, then I would look there first. I believe in '65 it was still external but at some point after that they went to the integral regulator...

Are you sure you have a 4.5L engine? I thought that model had the 6 cyl FI model? Was it a retrofit?

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

I should probably elaborate a little.

The car was originally fitted with a 2.2Lt mech injected six, which has been politely traded for a 4.5Lt from a 74 model (D Jet) engine.

The original 55 Amp alternator was operational when the conversion was completed and stayed in the car for around 12 months. However, a 108 Amp alternator was sourced as the car has been fitted with some accessories (don't worry guys, the original car has not been destroyed with a stoopidly big radio).

The original wiring was used to connect the new alternator (battery lead- red and paper insulated, earth - back with paper insulation and the trigger wire - pink)

Let me know if you would like me to elaborate a little further because this little light is extremly bright and makes you feel like the job was done with only 1/2 effort

Seriously uncool

What type of regulator are you using? The original metal can type or is the alternator internally regulated?

Did you eliminate the old regulator? If you eliminated it you will have the red charge light on constantly even though you are charging. You might be having a compatability issue with an internally regulated alt trying to deal with the old mechanical regulator.

The old alternator was internally regulated, as is the new one so can't see any issues there. However, I do recall vaguely reading something to do with some Merc's alternators having an external regulator unit aswell as the internal one that the alternator switches between depending on its charge requirements. I'm not really sure if this is correct and if it is, how it works. Perhaps it could be something along those lines maybe? The oddball thing with the light is it stays on consistently without flickering or dimming - the same as though you just had the ignition switched on without engine running.

Sorry to ressurect such an old thread.

Can I see or hear more about this V8ed Finny???????