Home » Public Forums » GMCnet » No Charging, light off in RUN, light on in ACCESSORY (How does this sound?)
| No Charging, light off in RUN, light on in ACCESSORY [message #322065] |
Mon, 14 August 2017 10:48  |
DetroitDan
Messages: 51
Registered: March 2017
Location: Taylor, MI
Karma: 0
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Every few days, I take the Chief out for about 15 miles - Up and down the freeway -- to see what breaks. When I finally get it ready to camp most of the running bugs should be swatted.
Last night, the coughed and died a couple of blocks from home. The battery voltage dropped below the Pertronix module's ignition level.
To get it home, I fired up the Honda and jumped the systems.
Here's what I found:
Engine running at the stock isolator:
Nothing worth counting (~0 VDC)at the alternator terminal on the isolator (Random, spurious voltages due to the high-impedance DMM)
12.6 VDC at the house side
10.8 at the chassis side
The GENERATOR light:
Illuminates in the ACCESSORY position
Does not illuminate in the RUN position (engine running or not)
I might not have tine to look at it today, but as I eat my lunch, looking at the schematic, here are my guesses:
1) The exciter wire lost connection with the alternator.
OR
2) The field or (field connection)in the alternator is open.
Here is my reasoning:
The generator is not charging because the field is not excited.
The GENERATOR indicator illuminates in ACCESSORY, because the ACCESSORY feed to the bulb is ground seeking through the bulb (and resistor) to un-powered loads connected to IGNITION 1.
The GENERATOR indicator does not illuminate in RUN, because, without the field load, the ACCESSORY and IGNITION 1 feeds are at the same potential. So, no current flows through the bulb (and resistor).
I ask those of you with more experience, other ideas?
I'll post what I find, but it may be a few days.
Dan Wallace
Detroit Metro
1974 Canyon Lands 260
Headers, 3.55, 16"
Floor plan 26-9
Honda 6010
Harrison 4-bag
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| Re: [GMCnet] No Charging, light off in RUN, light on in ACCESSORY [message #322068 is a reply to message #322065] |
Mon, 14 August 2017 10:54  |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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Do you have an APC cable
On Mon, Aug 14, 2017 at 8:49 AM Dan Wallace
wrote:
> Every few days, I take the Chief out for about 15 miles - Up and down the
> freeway -- to see what breaks. When I finally get it ready to camp most of
> the running bugs should be swatted.
>
> Last night, the coughed and died a couple of blocks from home. The
> battery voltage dropped below the Pertronix module's ignition level.
>
> To get it home, I fired up the Honda and jumped the systems.
>
>
> Here's what I found:
>
> Engine running at the stock isolator:
>
> Nothing worth counting (~0 VDC)at the alternator terminal on the isolator
> (Random, spurious voltages due to the high-impedance DMM)
> 12.6 VDC at the house side
> 10.8 at the chassis side
>
> The GENERATOR light:
> Illuminates in the ACCESSORY position
> Does not illuminate in the RUN position (engine running or not)
>
> I might not have tine to look at it today, but as I eat my lunch, looking
> at the schematic, here are my guesses:
>
> 1) The exciter wire lost connection with the alternator.
>
> OR
>
> 2) The field or (field connection)in the alternator is open.
>
> Here is my reasoning:
>
> The generator is not charging because the field is not excited.
>
> The GENERATOR indicator illuminates in ACCESSORY, because the ACCESSORY
> feed to the bulb is ground seeking through the bulb (and resistor) to
> un-powered loads connected to IGNITION 1.
>
> The GENERATOR indicator does not illuminate in RUN, because, without the
> field load, the ACCESSORY and IGNITION 1 feeds are at the same potential.
> So,
> no current flows through the bulb (and resistor).
>
>
> I ask those of you with more experience, other ideas?
>
> I'll post what I find, but it may be a few days.
>
>
>
>
>
>
>
>
>
> --
> Dan Wallace
> Detroit Metro
> 1974 Canyon Lands 260
> Headers, 3.55, 16"
> Floor plan 26-9
>
>
> _______________________________________________
> 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://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: No Charging, light off in RUN, light on in ACCESSORY [message #322072 is a reply to message #322065] |
Mon, 14 August 2017 11:07 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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It sounds like you are right on with your diagnosis. If you have an APC in line with the alternator, disconnect it temporarily and try again. I had a problem with the connections loosing tension on the APC connector on the back of the alternator. A little bit of tightening on the connectors took care of the problem. The APC was installed for years before the failure appeared. I'm assuming many, many hot and cold cycles caused it to loose tension.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: No Charging, light off in RUN, light on in ACCESSORY [message #322079 is a reply to message #322065] |
Mon, 14 August 2017 11:34 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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I think you are on the right track. Spray the connections to the plug going into the internal reg and or APC. Your house battery is dead. Charge it for a day with an external charger then see if it holds charge, then load test it. If either battery is failed in the mode where they get hot when attempting charging, that can take out your alt or isolator.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: No Charging, light off in RUN, light on in ACCESSORY [message #322084 is a reply to message #322065] |
Mon, 14 August 2017 12:47 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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No alternator output. Easiest cause - poor connection at the two-wire plug on the rear side of the alternator, clean it and bend the tabs to give better contact. Next is bad regulator or diode pak in the alternator. Both cheap and easy to replace but you hafta unship the alternator from the coach. A good parts house should be able to supply you the diode pak and the regulator. Ad a set of brushes, they're cheap. Take it apart, replace regulator and diodes (keep the takeouts, one or both might be OK). Take some crocus cloth to the slip rings, then note how the wire in the brush assembly keeps them out of the way until the thing is reassembled. Greas the back bearing and put it back together. Option - buy a lifetime warranty rebuild from Advance, Keep the receipt and every time it quits (it will) go get another one.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
[Updated on: Mon, 14 August 2017 12:51] Report message to a moderator |
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| SOLVED - No Charging, light off in RUN, light on in ACCESSORY - No Field. [message #322138 is a reply to message #322084] |
Tue, 15 August 2017 10:32 |
DetroitDan
Messages: 51
Registered: March 2017
Location: Taylor, MI
Karma: 0
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Member |
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Thank you all for the feedback!
The alternator field connection was open -- I did not open the case to find a root cause.
It looked pretty corroded inside, and since it was pretty noisy last week, it may have an open output diode too.
Also, it was kind of "rumbly" when I spun it by hand.
The resistance in the Chief's bulb/field tickler, remote sense, and output circuits are all acceptable.
So, I went to O'Reilly's, gave them $105, and they gave me a limited lifetime of charging bliss.
While I have it out, I will install a tickler circuit diode for resistor protection.
The Chief has less than 38k miles on the clock, but as you know, for many components, sitting is worse than operating.
Dan Wallace
Detroit Metro
1974 Canyon Lands 260
Headers, 3.55, 16"
Floor plan 26-9
Honda 6010
Harrison 4-bag
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| Re: [GMCnet] SOLVED - No Charging, light off in RUN, light on in ACCESSORY - No Field. [message #322139 is a reply to message #322138] |
Tue, 15 August 2017 10:42 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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You might want to rephrase that to" a lifetime of changing bliss" with
alternators. (Grin)
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Aug 15, 2017 8:33 AM, "Dan Wallace" wrote:
> Thank you all for the feedback!
>
> The alternator field connection was open -- I did not open the case to
> find a root cause.
>
> It looked pretty corroded inside, and since it was pretty noisy last week,
> it may have an open output diode too.
>
> Also, it was kind of "rumbly" when I spun it by hand.
>
> The resistance in the Chief's bulb/field tickler, remote sense, and output
> circuits are all acceptable.
>
> So, I went to O'Reilly's, gave them $105, and they gave me a limited
> lifetime of charging bliss.
>
> While I have it out, I will install a tickler circuit diode for resistor
> protection.
>
> The Chief has less than 38k miles on the clock, but as you know, for many
> components, sitting is worse than operating.
>
>
>
> --
> Dan Wallace
> Detroit Metro
> 1974 Canyon Lands 260
> Headers, 3.55, 16"
> Floor plan 26-9
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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