Generator light on ... alternator is charging...

[a.]

> Greetings,
> The 100 amp alternator on my 78 Royale is putting out 13+v, and yet the GEN light on the dash is on. The belt is tight and the connections are
> clean. Has anyone had this problem? Is there a relay or??? that might be faulty ... and Where might it be located? Any help would be greatly
> appreciated of course.
>
> Thanks,
If not already done, get and install an APC from Mr. ERF. Then, if that doesn't fix it, post back here.
http://bdub.net/gmcmotorhome.info/APC.html
--
73 23' Sequoia 4 Sale
73 23' CanyonLands Parts Unit 4 Sale
Upper Alabama
"When I grow up I am going to be a curmudgeon."

 

[alan m deluccio]

Greetings,

Can an APC go bad? I have had one installed on my GMC for quite a few years and just recently the GEN light has come on. Dim ... but on. It is a 78,
and I read that GM solved a problem in later models that occurred on earlier models that caused the GEN light to glow dim.The GEN is putting out
voltage ... approx 13 volts, so maybe the APC is bad? I had an 100 amp Alternator installed by Miguel at MGM in 2014, so I'm hoping it is not bad.

Comments and suggestions appreciated.

Thanks,
--
AMDGMCMan
Alan M DeLuccio
78 Royale with
Coachmen,Center Kitchen Floorplan
09 Harley Davidson Street Glide
65 Corvair Monza Convertible
96 RAV4 2 door Manual 4WD
Long Beach, CA

 

[Gene Fisher]

Your earlier post said you removed it
Barton told you the alternato volts should be 15 volts
Read here
http://www.gmcmotorhome.info/engine.html

Is prob not the APC

On Fri, Mar 24, 2017 at 9:00 PM Alan M DeLuccio
wrote:

> Greetings,
>
> Can an APC go bad? I have had one installed on my GMC for quite a few
> years and just recently the GEN light has come on. Dim ... but on. It is a
> 78,
> and I read that GM solved a problem in later models that occurred on
> earlier models that caused the GEN light to glow dim.The GEN is putting out
> voltage ... approx 13 volts, so maybe the APC is bad? I had an 100 amp
> Alternator installed by Miguel at MGM in 2014, so I'm hoping it is not bad.
>
> Comments and suggestions appreciated.
>
> Thanks,
> --
> AMDGMCMan
> Alan M DeLuccio
> 78 Royale with
> Coachmen,Center Kitchen Floorplan
> 09 Harley Davidson Street Glide
> 65 Corvair Monza Convertible
> 96 RAV4 2 door Manual 4WD
> Long Beach, CA
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://bdub.net/gmcmotorhome.info/
Alternator Protection Cable
http://bdub.net/gmcmotorhome.info/APC.html

 

[a.]

> Your earlier post said you removed it
> Barton told you the alternato volts should be 15 volts
> Read here
> http://www.gmcmotorhome.info/engine.html
>
> Is prob not the APC
15V sustained is too high, except in sub-zero tempeatures. But 13.6V minimum, generally. More than 14 after a long starter crank.
--
73 23' Sequoia 4 Sale
73 23' CanyonLands Parts Unit 4 Sale
Upper Alabama
"When I grow up I am going to be a curmudgeon."

 

[a.]

> > Your earlier post said you removed it
> > Barton told you the alternato volts should be 15 volts
> > Read here
> > http://www.gmcmotorhome.info/engine.html
> >
> > Is prob not the APC
> 15V sustained is too high, except in sub-zero tempeatures. But 13.6V minimum, generally. More than 14 after a long starter crank.
Oops. Forgot about the 0.7V drop across the isolator. 15V is not too high.
--
73 23' Sequoia 4 Sale
73 23' CanyonLands Parts Unit 4 Sale
Upper Alabama
"When I grow up I am going to be a curmudgeon."

 

[john r. lebetski]

He needs to tell us how and where he is metering. 13.6-14.2 is ok after the isolator. Where the 13 is metered is important as the sense to the
alternator is after the isolator and 13 minus .7 would cause the lamp to glow.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[Gene Fisher]

Here is the bible, do this
http://www.gmcmhphotos.com/photos/data/15/GMC_charging_system_checkout.pdf

On Sat, Mar 25, 2017 at 2:49 PM John R. Lebetski
wrote:

> He needs to tell us how and where he is metering. 13.6-14.2 is ok after
> the isolator. Where the 13 is metered is important as the sense to the
> alternator is after the isolator and 13 minus .7 would cause the lamp to
> glow.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://bdub.net/gmcmotorhome.info/
Alternator Protection Cable
http://bdub.net/gmcmotorhome.info/APC.html

 

[alan m deluccio]

A bench test performed on the alternator showed that a diode was bad. After dimantling it and further investigation the capacitor was defective as
well. I also noticed that the unit had an unusual whine since it was installed. Needless to say I replaced it & all is well.
--
AMDGMCMan
Alan M DeLuccio
78 Royale with
Coachmen,Center Kitchen Floorplan
09 Harley Davidson Street Glide
65 Corvair Monza Convertible
96 RAV4 2 door Manual 4WD
Long Beach, CA

 

[john r. lebetski]

A bad diode will cause 1 of 3 phases to be missing. The "gap" in output will cause louder whine. This may have taken out the filter cap is my guess.
--
John Lebetski
Woodstock, IL
77 Eleganza II