| [GMCnet] Engine generator light on [message #285039] |
Sat, 15 August 2015 17:00  |
Advanced Concept Ener
Messages: 112
Registered: December 2014
Karma: 0
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Ok I have a MAC dash and the tell tale engine generator light came on. It first flickered on and of as I went from acceleration to braking then came on full time. Belt is ok. Voltmeter reads 14.7 volts. Double checked with VOM and they both read 14.7 volts. Battery on generator was dead and generator would not start until engine ran. Even after starting generator would not power up coach bus. It has a battery paralleling solid state device. I am charging up house batteries to see if that affects anything. Don't know if these are related but figured I would give you the full initial analysis. I guess it c outdoor be I knocked something loose when in engine compartment changing AC compressor and replacing and tightening belts.
Jon Darcy ACES
North Jersey 76 stretch, flares, 4 bag, Alcoa's, bunkhouse,MAC Dash
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| Re: [GMCnet] Engine generator light on [message #285085 is a reply to message #285039] |
Sun, 16 August 2015 01:50  |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Advanced Concept Ener wrote on Sat, 15 August 2015 15:00Ok I have a MAC dash and the tell tale engine generator light came on. It first flickered on and of as I went from acceleration to braking then came on full time. Belt is ok. Voltmeter reads 14.7 volts. Double checked with VOM and they both read 14.7 volts. Battery on generator was dead and generator would not start until engine ran. Even after starting generator would not power up coach bus. It has a battery paralleling solid state device. I am charging up house batteries to see if that affects anything. Don't know if these are related but figured I would give you the full initial analysis. I guess it c outdoor be I knocked something loose when in engine compartment changing AC compressor and replacing and tightening belts.
Darcy,
I am not sure how the telltale in the Mac Dash works. I think most of them have a diode circuit that triggers the light. The fact that it started flickering at lower RPMs and moved on to full light makes me think the alternator was failing. But 14.7 shows higher than a battery at rest. I am assuming that this is with the engine running and no shore or generator. You can test that theory by shutting the engine off while keeping the tester attached. Voltage should drop, probably to the 13s.
I don't think the generator battery would cause the alternator light to come one. If I remember right, without some changes in the system the Onan battery is charged by the Onan. Many of us have that rear battery (or one of more capacity) as part of the house system and not charged by the Onan. My Onan runs the charger that charges the house and engine battery.
Sorry I am not more help. You are doing the right thing, putting a voltage test on it. Unless changed that line from the Alternator lug (the big nut on the back of the unit) goes to the center post of the isolator in front under the rider's side eyebrow. You can test the upper and lower posts as well. There will be a slight drop in voltage on both the house and the engine battery. That is just the nature of the unit.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] Engine generator light on [message #285087 is a reply to message #285039] |
Sun, 16 August 2015 02:38 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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I am not sure about the Mac dash, but read here
http://www.gmcmotorhome.info/engine.html#alternator
On Saturday, August 15, 2015, Advanced Concept Energy Solutions <
aces4nrg@gmail.com> wrote:
> Ok I have a MAC dash and the tell tale engine generator light came on. It
> first flickered on and of as I went from acceleration to braking then came
> on full time. Belt is ok. Voltmeter reads 14.7 volts. Double checked with
> VOM and they both read 14.7 volts. Battery on generator was dead and
> generator would not start until engine ran. Even after starting generator
> would not power up coach bus. It has a battery paralleling solid state
> device. I am charging up house batteries to see if that affects anything.
> Don't know if these are related but figured I would give you the full
> initial analysis. I guess it c outdoor be I knocked something loose when in
> engine compartment changing AC compressor and replacing and tightening
> belts.
>
> Jon Darcy ACES
> North Jersey 76 stretch, flares, 4 bag, Alcoa's, bunkhouse,MAC Dash
> _______________________________________________
> 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: [GMCnet] Engine generator light on [message #285091 is a reply to message #285039] |
Sun, 16 August 2015 05:46 |
Jim at the Co-op
Messages: 291
Registered: May 2014
Location: Orlando Florida
Karma: 2
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Jon, give me a call in the morning, I can step you through my install, no problem,
Jim Bounds
Sent from my T-Mobile 4G LTE Device
-------- Original message --------
From: George Beckman
Date: 08/16/2015 2:50 AM (GMT-05:00)
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Engine generator light on
Advanced Concept Ener wrote on Sat, 15 August 2015 15:00
> Ok I have a MAC dash and the tell tale engine generator light came on. It first flickered on and of as I went from acceleration to braking then
> came on full time. Belt is ok. Voltmeter reads 14.7 volts. Double checked with VOM and they both read 14.7 volts. Battery on generator was dead and
> generator would not start until engine ran. Even after starting generator would not power up coach bus. It has a battery paralleling solid state
> device. I am charging up house batteries to see if that affects anything. Don't know if these are related but figured I would give you the full
> initial analysis. I guess it c outdoor be I knocked something loose when in engine compartment changing AC compressor and replacing and tightening
> belts.
Darcy,
I am not sure how the telltale in the Mac Dash works. I think most of them have a diode circuit that triggers the light. The fact that it started
flickering at lower RPMs and moved on to full light makes me think the alternator was failing. But 14.7 shows higher than a battery at rest. I am
assuming that this is with the engine running and no shore or generator. You can test that theory by shutting the engine off while keeping the tester
attached. Voltage should drop, probably to the 13s.
I don't think the generator battery would cause the alternator light to come one. If I remember right, without some changes in the system the Onan
battery is charged by the Onan. Many of us have that rear battery (or one of more capacity) as part of the house system and not charged by the Onan.
My Onan runs the charger that charges the house and engine battery.
Sorry I am not more help. You are doing the right thing, putting a voltage test on it. Unless changed that line from the Alternator lug (the big nut
on the back of the unit) goes to the center post of the isolator in front under the rider's side eyebrow. You can test the upper and lower posts as
well. There will be a slight drop in voltage on both the house and the engine battery. That is just the nature of the unit.
--
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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