I had an earlier post decribing the problem of all the dash lights coming on in my 88 300E. I read some posts and got some advice and changed the voltage regulator. The brushes were worn and when I changed it all the dash lights went out and the car ran fine.

I started it this morning to warm it up and no problems. I went back in the house and when I came out the ABS light was on then the SRS light came on and then bulb out indicator. The other issues are when I hit the brakes the tack drops to 0 the idle doesn't change it just drops and when I turn on the lights the tack drops and it sounds like the car is going to stall.

Any ideas?

Thanks in advance.

Jon

Sounds like you may need more then a regulartor..how many volts is your system putting out at idle?

What brand of regulator did you install?

Also, letting your car sit and idle for extended periods does it zero favours as well as wastes a Lot of gas (engines are very inneficent 2 idle).

Check your OVP fuse as well.

Jonathan

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Jonathan Hodgman
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The #'s were Battery w/out the car running gave out 12.56 with the car at idle and warm it registered 14.27. What is the OVP fuse and where is it? and the reason I warm it up is it's better than driving down the street with my head out the window while I wait for the window to de-fog.

One other thing I forgot to mention is when I tried to put on the rear defogger the light just blinks and it wouldn't go on.

Thanks

Well your output is within spec..........

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former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL

If you are getting blinking lights when you press an accesory that's your #1 indication you don't have enough voltage. Check your output again.

The OVP is a small silver box located behind the battery in your car..has a 10 amp gm style fuse in it..check that fuse.

Jonathan

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Jonathan Hodgman
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Enthusiast Service, Restoration & Tuning.
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Located in the Atlanta area
Specializing in all pre and post merger AMG's including Hammers and DOHC M117 engines.
Mercedes Repair Atlanta

Thanks for the tips Jonathan I'll check it when I get home.

When I got home I started it and the output was down to 9 and change then it just died. Took a chance that it was the battery. I have no idea when the previous owner put the one that was in there. Fired right up and no lights were on. The battery had been sitting on my bench for awhile so I'm letting it run for a bit and will go re-check the output. If it's normal problem solved if not then will check fuses then change the alternator if necessary. Any other ideas?

Well I let the battery charge a bit and the output is around 11 and change. So it's better than the 9 with the old battery but not better than the 14 I was getting with the old battery and old voltage regulator.

There are no lights on the dash and all the accesories are working so one problem was solved but now the alternator is not really charging the battery. Could it be fuses? or should I bite the bullet and get an alternator?

For my curiousity, did you also replace the brushes too, or just the alternator? Worn brushes can make the voltage come and go, and if they've gone, it would explain all that has happened to you since you changed the regulator.

Isn't there a way to measure the output from the alternator alone?

I don't know I'm not good with electricl issues. Could it be a faulty regulator?

When driving Wife's 300E across (very deserted) SW Kansas, suddenly cruise control shut off. Then radio wouldn't work. Got to a town, and tach and turn signals didn't work. When shut off engine, car would not restart.

These are all symptoms of failing alternator.

Nice that the car "shuts down" various loads to get you home.

Never saw a red charging light.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
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If the alternator fails, all of the electrical loads must run from the battery. Since loads have different voltage requirements, the lower the battery voltage goes, the more loads 'shut down.'

I had a similar experience with a diesel you may find entertaining.

http://www.peachparts.com/shopforum/showthread.php?t=128023&highlight=alternator

You were lucky that the battery voltage did not get low enough that your fuel injection or ignition systems did not shut down.

I'm confused!

A proper electrical system includes:
1. A 'good' alternator core.
2. A 'good' regulator, with brushes making proper contact.
3. A 'good' battery, capable of holding a full charge.
4. 'Good' wiring connections between the battery, alternator and ground.

You should read 13-14 volts at idle with no large loads such as headlights, blower motor on high, or rear defogger. 11 volts at idle means either the alternator/regulator is not producing a charge, or the battery is not taking a charge.

Let's go back what I understand that you have done so far...

1. You replaced the regulator.
2. You replaced the battery with a 'spare' battery, not brand-new.
3. You charged the battery, but only got 9-11 volts.
Was this with a portable charger, or using the car at idle?

So, we don't know about how good the battery is...

The battery is new I bought it but never put it in. I actually junked the car it was supposed to go in. It has just been sitting on my work bench for about 4 monthes.

The reason I think it could be a bad regulator is I was getting 14 with the old regulator but all my idiot lights were on so that's why I changed it and the brushes were worn. All of the other issues started after I changed the regulator. So it could be a bad regulator or was the alternator on the way out and by changing the regulator it finally just crapped out.