Alternator Dash Light Flicker
 

After pulling up at work this morning in my 88, I noticed that the dash charge light would flicker at idle and kind of dim out when reved. I recently rebuilt my motor and the alternator worked OK for a couple of days, now this. I was wondering if there is a quick way to diagnose this problem and also where the main groung straps on the car are. I'm guessing transmission because I didn't remove any while pulling the engine.

I don't know where it is on an '88, but there SHOULD be a 30 mm or so wide, braided copper ground strap from the body to the front transaxle crossmember ... maybe the Bentley manual shows where it is ...



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Warren Hall
1973 911S Targa

beetos,

My 73T does the same thing. I have a freshly rebuilt motor and a new alternator with an internal regulator. I don't think there is any need for concern though...maybe you could increase your idle rpm a little if the light really bothers you. I would be concerned if the light stays on for any extended period of time though...

Bill

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William Armentrout
1973 911T
2.7 carerra rs specs
www.geocities.com/william_armentrout

Isn't there three diodes in the alternator and regulator system and, when one goes out things are still okay but it makes the alternator light glow? Enlighten me please, as I am 'in the dark.'

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'83 SC

The diodes take the sine wave produced by the alternator and rectify it into a direct current (dc) that is used to charge the battery. With one diode open, the output of the alternator is substantially reduced. I believe that if you lose one of the diodes in the alternator, you are not OK.

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Bob Thayer
1971 911T
rthayer@hdrinc.com

I have a 74 that has a rebuilt engine and Alt with internal regulator.

My dash light goes on when I start the engine and will stay on until I rev the engine to above 2000 RPM - then it goes out and stays out.

When I pulled my gauges to do the faces I looked to see if the modification that Porsche recommends ( I think it is a resistor across the + wires)was done and I could not find anything like what the P book showed.

The car runs fine and I have had no problems with it so I have just learned to live with it - much the same as using the throttle lever to ajust the warm up idle.

Don't ya` just love these older cars ?

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Tom Sharpes
74 911 Targa
http://members.rennlist.com/5150targa

It is indeed typical for alternator lights to stay on until the engine reaches a certain rpm, and then go off and stay off. Not unusual and no cause for alarm, that is.

I appreciate the additional info regarding diodes. Again, the symptom is an alternator light that barely glows much of the time.

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'83 SC

When this happened on our 1987 Turbo it was the alternator failing (insufficient output). The light on the dash shows which way the current is flowing, I.E. if the alternator is working correctly and sending current to the battery the light will be out, other wise it will glow and the degree of brightness depends on how much current is flowing from the battery to the rest of the circuits. There was a good explanation of this about 1 1/2 years ago in Panorama. Good luck.

I had this problem before and it was the carbon brushes in the alt. not making good contact....for what it's worth regards jer

Thanks guys,
I returned to the car after work and all it needed was to be reved as most of you say to eliminate the light. I checked with Zimms, they do a regulator for the alt, I guess I might just change it to be on the safe side. They say the brushes come with it.

[This message has been edited by beetos (edited 08-29-2000).]