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NoSparkNeeded 08-20-2008 03:25 PM

300TD alt. light
I noticed this morning in the dark driving to work that when I applied my brakes, the alt. light would faintly glow. Then messing around I discovered
that it did it when I used the turn signals as well.You can't see this happening in the day time because it's way too faint. Hydrometer indicates a fully charged battery.
Does it look like my alternator is failing or something else?

Thecorrupterx 08-20-2008 03:46 PM

you could ride by an autozone and have them do their free on car test, that would at least get you started in the right direction.

toomany MBZ 08-21-2008 05:41 AM

Often times this an indication of a failing voltage regulator, a cheap and easy fix. It's not too hard to pull the old one and inspect it.

NoSparkNeeded 08-23-2008 05:29 PM

Hasn't happened since
Drove to work the last couple days and no repeat on the dim glowing
alternator light when braking. Intermittent problems drive me bonkers:(.
I've been living with a V-12 Jag for many years and should be used to it
by now:eek:.

pawoSD 08-23-2008 11:07 PM

I had that happen before when going through a lot of heavy rain.....then it went away. I'd get a voltmeter and check the system voltage when the car is on at idle.....and at maybe 1500rpm.....should be between 13.2 and 14V....if lower than the alternator or voltage regulator has an issue.

bustedbenz 08-23-2008 11:20 PM

This happened to me as my alternator was dying last year. Only a faint little signal under certain conditions made it to the light at first. It never did glow nice and bright, but one day I pulled into the yard, having noticed that the headlights had been getting dimmer over the last 30 minutes of driving, and it wouldn't re-start itself. Replaced the alternator and the regulator (having tried a regulator and still reading low charging voltage), charged the battery, and haven't had trouble yet.

I've always wished these cars had volt AND ammeters just for the information. Ammeter would show whether the system was charging or discharging, and provide a way to monitor how much of a drain it was coping with. Voltmeter would be somewhat superfluous if the ammeter was present, but hey, more data is always good.

I know you can get volt meters that plug into the cigarette lighter and display what it's reading, that'd be better than nothing but I just haven't stopped to get one.

pawoSD 08-23-2008 11:26 PM

I added a voltmeter a long time ago to my tells me how wimpy the 65A alternator is on a regular basis.....I am looking to upgrade sometime in the near future to the 115A unit....

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