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billonwheels 08-26-2012 07:08 PM

Generator Lights on dim....
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Alright guys I got my 1970 Pontiac Grand Prix home, The 455 is running great. I changed mt 3 wire Alternator to a 1 wire and the dash lights and the interior lights are inop. I can track that down but the Gen light in the dash is dim. What can I do to iliminate that light and how do I get my Head lights to not dim with the raise and fall of the rpms? I have a powermaster 100 amp alternator, with March pullies, Flex Lite electric fan.

S10 Racer 08-26-2012 08:19 PM

Dim lights sound like a bad ground somewhere. Have you checked those?

billonwheels 08-26-2012 08:27 PM

no just got the car back home, I was thinking that also. I think I'll pull it in the garage tonight and check.

astroracer 08-27-2012 05:23 AM

You may want to do some reading. Look here: - Electrical Tech
Read the "voltage sensing" article then read the "one wire vs. three wire" article.
Then dig out your three wire and put it back on...

75gmck25 08-27-2012 05:47 AM

If you switched from three wire to one wire, you now have a two wire plug that is not connected. One of those wires goes to the generator light in the dash. When that wire is disconnected the generator light will come on, which is exactly what its supposed to do.

One wire alternators also kick in based on RPM only, since they do not have a voltage sense wire (the other wire you disconnected). The alternator may not kick in at idle, but once it does get enough RPM the power should keep up.


joe_padavano 08-27-2012 01:17 PM

Once again, what is the attraction of the one-wire alternator? GM doesn't typically include parts that are not needed (like those two extra wires). The aftermarket has brainwashed hobbyists into thinking they must have a one-wire, and now they are selling a $20 module to replace the idiot light function that you got for free with the factory alternator... :rolleyes:

EOD Guy 08-27-2012 04:09 PM

If you switch from a 3 wire to a 1 wire and leave the alt connector unpluged, the light shouldn't come on because it's not getting a ground from the internal voltage regulator/rectifier...... if you are getting a light, then the connector has shorted to ground and if that's shorted to ground....odds are so is the #2 wire, which is connected to the hot side of the system...... which is bad.

The one wire has an internal #2 wire or sense wire and as GMC stated you have to get the rpm's up in order for the regulator to see the demand etc.....

In order to eliminate the gen light, simply make sure the wire that used to go to the alt, #1 wire, ISN'T grounded. As far as you dash lights....... prob loose or bad ground.

billonwheels 09-05-2012 09:54 PM

2 Attachment(s)
replaced a few fuses, and some dash lights and everythings working, looking at replacing Guage lights with led's..... blacked out my rear lens.....looks good. Thanks for the comments.

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