Electrical help

D

Digger

New member
Apr 11, 2018
16
0
1
66
Aledo, Illinois
I am wondering where I can begin to understand the basics of automotive (gmcmh) electricity. Other than knowing what a battery is and the fact that
it has a positive and negative terminal, that is about the extent of my electrical prowess. (Oh yah, fuses, I know when one is blown!!) Is there a
book or manual or whatever for me to read and understand the basics of electrical automotive engineering. Thanks
 
There are 3 electrical systems in the GMC and most motorhomes.

The first is the engine driven 12 volt system that is not much different that any car or truck built on the 1970's. It has an alternator to provide
power and a bunch of accessories like ignition, heater fan, lights, radio, battery for storage and to supply the starter.

The second is another 12 vdc system that supplies 12vdc to all of the house stuff like inside lights, exhaust fans, etc. This system has a separate
battery or batteries that is charged from a 120vac converter when plugged in to 120vac or by the engine driven alternator when going down the road.

The last system is 120VAC. It is supplied power by being plugged in somewhere or by running the generator (usually an Onan). This system supplies
higher current things like the water heater , microwave, or converter to charge the 12vdc batteries.

When you want to work on something electrical, first determine which of the 3 systems it is on and then use the appropriate diagram from the three GMC
electrical diagrams in the GMC maintenance manual.

You can also order very large diagrams from Ken Henderson.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
And read here
http://bdub.net/gmcmotorhome.info/list.html

> There are 3 electrical systems in the GMC and most motorhomes.
>
> The first is the engine driven 12 volt system that is not much different
> that any car or truck built on the 1970's. It has an alternator to provide
> power and a bunch of accessories like ignition, heater fan, lights, radio,
> battery for storage and to supply the starter.
>
> The second is another 12 vdc system that supplies 12vdc to all of the
> house stuff like inside lights, exhaust fans, etc. This system has a
> separate
> battery or batteries that is charged from a 120vac converter when plugged
> in to 120vac or by the engine driven alternator when going down the road.
>
>
> The last system is 120VAC. It is supplied power by being plugged in
> somewhere or by running the generator (usually an Onan). This system
> supplies
> higher current things like the water heater , microwave, or converter to
> charge the 12vdc batteries.
>
> When you want to work on something electrical, first determine which of
> the 3 systems it is on and then use the appropriate diagram from the three
> GMC
> electrical diagrams in the GMC maintenance manual.
>
> You can also order very large diagrams from Ken Henderson.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> 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
 
Scott,

Here, you'll find several publications by GMCers which are specifically
about the GMC's electrical system: http://gmceast.com/technical/

As for those large wiring diagrams, it's not me, but my son, Alan, who
prints and sells them:
https://docs.google.com/viewer?url=http%3A%2F%2Fwww.bdub.net%2FGMC_Motorhome_Wiring_Diagrams.pdf
or
https://goo.gl/3CtDtm

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

On Sat, Nov 24, 2018 at 11:51 PM Scott Fippinger <

> I am wondering where I can begin to understand the basics of automotive
> (gmcmh) electricity. Other than knowing what a battery is and the fact that
> it has a positive and negative terminal, that is about the extent of my
> electrical prowess. (Oh yah, fuses, I know when one is blown!!) Is there a
> book or manual or whatever for me to read and understand the basics of
> electrical automotive engineering. Thanks
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Thanks, everyone, I have plenty of reading today during this storm. What started all of this was turn signals, they quit working which led me to the
fuse box in the glove compartment which Bob Dunahugh suggested was probably contact problem. He was right. I filed the points for the old glass
fuses which helped but now I'm wondering if I could actually replace the fuse box with an updated one. I was researching on the gmcnet and found a
box from I think it was west marine but does anyone have any suggestions or thoughts.
 
Scott,

I, trained as an Electrical Engineer, have never gotten up the nerve to
replace the firewall fuse block -- even when I replaced the entire dash and
HVAC system. That's a unique box which connects directly to the
through-the-firewall wiring. Replacing it would be a MAJOR wiring task.
CAREFULLY cleaning each of the contacts, with a spray cleaner (such as CRC
2-26) and fine wet/dry sandpaper (220-300 grit) wrapped around a short
piece of dowel will be a MUCH easier and almost as effective solution.

JMHO,
I
Ken H.

On Sun, Nov 25, 2018 at 9:27 AM Scott Fippinger <

> Thanks, everyone, I have plenty of reading today during this storm. What
> started all of this was turn signals, they quit working which led me to the
> fuse box in the glove compartment which Bob Dunahugh suggested was
> probably contact problem. He was right. I filed the points for the old
> glass
> fuses which helped but now I'm wondering if I could actually replace the
> fuse box with an updated one. I was researching on the gmcnet and found a
> box from I think it was west marine but does anyone have any suggestions
> or thoughts.
>
>
 
Those are readily available from 'most any parts supplier. But, they don't
address the problem of corroded connections. Nor are they an economical
solution for MOST of the fuses, which seldom blow. They ARE good for heavy
loads and "must have" circuits.

Ken H.

On Sun, Nov 25, 2018 at 1:47 PM Scott Fippinger <

> I did see in Applied GMCMH a fuse style breaker switch to replace glass
> fuses
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
The vendor to use for this kind of stuff is Waytek Wire or Del City. Either one is totally about 12V wiring. Especially Waytek. They have EATON/Littlefuse fuse blocks as used in current cars and trucks. Several models have a bussed common for all fuses or all separate. They take the now standard Delphi connectors that snap into the fuse holder directly. Pricing is not out of this world either.

>
>
> Scott,
>
> Here, you'll find several publications by GMCers which are specifically
> about the GMC's electrical system: http://gmceast.com/technical/
>
> As for those large wiring diagrams, it's not me, but my son, Alan, who
> prints and sells them:
> https://docs.google.com/viewer?url=http%3A%2F%2Fwww.bdub.net%2FGMC_Motorhome_Wiring_Diagrams.pdf
> or
> https://goo.gl/3CtDtm
>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
> www.gmcwipersetc.com
>
>
> On Sat, Nov 24, 2018 at 11:51 PM Scott Fippinger <

>
> > I am wondering where I can begin to understand the basics of automotive
> > (gmcmh) electricity. Other than knowing what a battery is and the fact that
> > it has a positive and negative terminal, that is about the extent of my
> > electrical prowess. (Oh yah, fuses, I know when one is blown!!) Is there a
> > book or manual or whatever for me to read and understand the basics of
> > electrical automotive engineering. Thanks
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Automotive electrical systems have been an evolutionary process. Originally
the only electrical concern was ignition. A number of systems were tried.
Make n break, hit and miss, magneto, dry cell battery, wet cell battery,
all were tried.
What was kinda settled on was points and condenser located inside a
weather resistant housing with an integral rotor and cap with multiple
conductors to each plug. Initially timing was static, and no advance
mechanism was used. Then came manually advanced spark, followed by
mechanical and finally vacuum advance.
Then, someone wanted headlights so they could drive at night. So,
batteries were used, then charging systems to keep them charged, and more
electrical demands led to improvements. Most of the systems were 6 volt.
As demands grew, voltage increased as did automotive wire harnesses.
With 12 volt systems, came through the firewall harnesses like our coaches
use.
Modern cars? A further step in the process. And the beat goes on.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Tue, Nov 27, 2018, 9:53 AM RICHARD/MARLI SHOOP
wrote:

> The vendor to use for this kind of stuff is Waytek Wire or Del City.
> Either one is totally about 12V wiring. Especially Waytek. They have
> EATON/Littlefuse fuse blocks as used in current cars and trucks. Several
> models have a bussed common for all fuses or all separate. They take the
> now standard Delphi connectors that snap into the fuse holder directly.
> Pricing is not out of this world either.
> > On November 25, 2018 at 4:50 AM Ken Henderson

> >
> >
> > Scott,
> >
> > Here, you'll find several publications by GMCers which are specifically
> > about the GMC's electrical system: http://gmceast.com/technical/
> >
> > As for those large wiring diagrams, it's not me, but my son, Alan, who
> > prints and sells them:
> >
> https://docs.google.com/viewer?url=http%3A%2F%2Fwww.bdub.net%2FGMC_Motorhome_Wiring_Diagrams.pdf
> > or
> > https://goo.gl/3CtDtm
> >
> > Ken H.
> > Americus, GA
> > '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> > Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
> > www.gmcwipersetc.com
> >
> >
> > On Sat, Nov 24, 2018 at 11:51 PM Scott Fippinger <

> >
> > > I am wondering where I can begin to understand the basics of automotive
> > > (gmcmh) electricity. Other than knowing what a battery is and the
> fact that
> > > it has a positive and negative terminal, that is about the extent of my
> > > electrical prowess. (Oh yah, fuses, I know when one is blown!!) Is
> there a
> > > book or manual or whatever for me to read and understand the basics of
> > > electrical automotive engineering. Thanks
> > >
> > > _______________________________________________
> > > GMCnet mailing list
> > > Unsubscribe or Change List Options:
> > > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> > >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
How I started learning about this stuff was over the hood of model T, then
Model A, then Fords of the 40's and 50's. When they put the valves in the
heads instead of the blocks where they should be, I lost interest in Fords.
I switched to Olds Rockets and Cadillacs, then VW and other Foreign
(european) cars.
Japanese (rice grinders) were held in low esteem in my circle of
friends. Still are, by some.
My formal training started with General Motors Training Centers, then,
Porsche/Audi/ VW/Dasher/etc. Blue Mountain Community College Diesel School,
Mercury OB, OMC, VOLVO PENTA, Honda MC, etc., etc.
It continued until my retirement as a Vocational Instructor for the
Department of Corrections in 1996.
Oh yes somewhere in there was a drag racing addiction, a formal
apprenticeship, partnership in an Automotive Machine Shop, marriage, kids,
etc.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Automotive electrical systems have been an evolutionary process.
> Originally the only electrical concern was ignition. A number of systems
> were tried. Make n break, hit and miss, magneto, dry cell battery, wet cell
> battery, all were tried.
> What was kinda settled on was points and condenser located inside a
> weather resistant housing with an integral rotor and cap with multiple
> conductors to each plug. Initially timing was static, and no advance
> mechanism was used. Then came manually advanced spark, followed by
> mechanical and finally vacuum advance.
> Then, someone wanted headlights so they could drive at night. So,
> batteries were used, then charging systems to keep them charged, and more
> electrical demands led to improvements. Most of the systems were 6 volt.
> As demands grew, voltage increased as did automotive wire harnesses.
> With 12 volt systems, came through the firewall harnesses like our coaches
> use.
> Modern cars? A further step in the process. And the beat goes on.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>
> On Tue, Nov 27, 2018, 9:53 AM RICHARD/MARLI SHOOP

>
>> The vendor to use for this kind of stuff is Waytek Wire or Del City.
>> Either one is totally about 12V wiring. Especially Waytek. They have
>> EATON/Littlefuse fuse blocks as used in current cars and trucks. Several
>> models have a bussed common for all fuses or all separate. They take the
>> now standard Delphi connectors that snap into the fuse holder directly.
>> Pricing is not out of this world either.
>> > On November 25, 2018 at 4:50 AM Ken Henderson

>> >
>> >
>> > Scott,
>> >
>> > Here, you'll find several publications by GMCers which are specifically
>> > about the GMC's electrical system: http://gmceast.com/technical/
>> >
>> > As for those large wiring diagrams, it's not me, but my son, Alan, who
>> > prints and sells them:
>> >
>> https://docs.google.com/viewer?url=http%3A%2F%2Fwww.bdub.net%2FGMC_Motorhome_Wiring_Diagrams.pdf
>> > or
>> > https://goo.gl/3CtDtm
>> >
>> > Ken H.
>> > Americus, GA
>> > '76 X-Birchaven w/Cad500/Howell EFI & EBL,
>> > Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
>> > www.gmcwipersetc.com
>> >
>> >
>> > On Sat, Nov 24, 2018 at 11:51 PM Scott Fippinger <

>> >
>> > > I am wondering where I can begin to understand the basics of
>> automotive
>> > > (gmcmh) electricity. Other than knowing what a battery is and the
>> fact that
>> > > it has a positive and negative terminal, that is about the extent of
>> my
>> > > electrical prowess. (Oh yah, fuses, I know when one is blown!!) Is
>> there a
>> > > book or manual or whatever for me to read and understand the basics of
>> > > electrical automotive engineering. Thanks
>> > >
>> > > _______________________________________________
>> > > GMCnet mailing list
>> > > Unsubscribe or Change List Options:
>> > > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>> > >
>> > _______________________________________________
>> > GMCnet mailing list
>> > Unsubscribe or Change List Options:
>> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
 
When I was about 8-10 years old (1945-1947) I found, in my grandparents'
attic, a copy of Audel's Automotive Guide. One of my uncles had bought it
some time earlier -- probably in the late '30's or early '40's. Reading
that cover-to-cover was my introduction to auto mechanics. I wound up
thinking all auto engines had poured babbitt bearings! And I knew how to
do them, including scraping for clearance! :-)

So, if some of my comments seem a bit outdated, just remember: That was my
total formal automotive education -- all the rest was OJT. :-)

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

> How I started learning about this stuff was over the hood of model T, then
> Model A, then Fords of the 40's and 50's. When they put the valves in the
> heads instead of the blocks where they should be, I lost interest in Fords.
> I switched to Olds Rockets and Cadillacs, then VW and other Foreign
> (european) cars.
> Japanese (rice grinders) were held in low esteem in my circle of
> friends. Still are, by some.
> My formal training started with General Motors Training Centers, then,
> Porsche/Audi/ VW/Dasher/etc. Blue Mountain Community College Diesel School,
> Mercury OB, OMC, VOLVO PENTA, Honda MC, etc., etc.
> It continued until my retirement as a Vocational Instructor for the
> Department of Corrections in 1996.
> Oh yes somewhere in there was a drag racing addiction, a formal
> apprenticeship, partnership in an Automotive Machine Shop, marriage, kids,
> etc.
>
...
 
Ken,

Ojt. On the Job Training?

Sully
Bellevue wa

On Tue, Nov 27, 2018 at 4:21 PM Ken Henderson
wrote:

> When I was about 8-10 years old (1945-1947) I found, in my grandparents'
> attic, a copy of Audel's Automotive Guide. One of my uncles had bought it
> some time earlier -- probably in the late '30's or early '40's. Reading
> that cover-to-cover was my introduction to auto mechanics. I wound up
> thinking all auto engines had poured babbitt bearings! And I knew how to
> do them, including scraping for clearance! :-)
>
> So, if some of my comments seem a bit outdated, just remember: That was my
> total formal automotive education -- all the rest was OJT. :-)
>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
> www.gmcwipersetc.com
>
>

>
> > How I started learning about this stuff was over the hood of model T,
> then
> > Model A, then Fords of the 40's and 50's. When they put the valves in the
> > heads instead of the blocks where they should be, I lost interest in
> Fords.
> > I switched to Olds Rockets and Cadillacs, then VW and other Foreign
> > (european) cars.
> > Japanese (rice grinders) were held in low esteem in my circle of
> > friends. Still are, by some.
> > My formal training started with General Motors Training Centers,
> then,
> > Porsche/Audi/ VW/Dasher/etc. Blue Mountain Community College Diesel
> School,
> > Mercury OB, OMC, VOLVO PENTA, Honda MC, etc., etc.
> > It continued until my retirement as a Vocational Instructor for the
> > Department of Corrections in 1996.
> > Oh yes somewhere in there was a drag racing addiction, a formal
> > apprenticeship, partnership in an Automotive Machine Shop, marriage,
> kids,
> > etc.
> >
> ...
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Yep. OJT=On the Job Training. The military's primary method of producing
experienced craftsmen. For example, in USAF, every member has an AFSC (Air
Force Specialty Code). One newly assigned to an AFSC, perhaps as a
Tech(nical) School graduate, picks up the five digit (XYZ3A) AFSC. As the
member progresses in his field, with formal OJT, exams, etc., and serves a
prescribed period of practice, the 4th digit will be advanced to a 5
(XYZ5A). And later, when he's reached the "ultimate" of skill in the
field, he/she'll be awarded the "7 Level" -- XYZ7A. For most fields, there
are correspondence courses and/or residence courses which are prerequisite
to advancement through the "Skill Levels". Too bad more of our youth can't
receive such effective training.

(My OJT wasn't anything like that formal -- I just tinkered alone and under
the tutelage of a lot of sometimes skilled mechanics! :-)

Ken H.
Lt.Col, USAF, Ret. http://www.gmcwipersetc.com

> Ken,
>
> Ojt. On the Job Training?
>
> Sully
> Bellevue wa
>
>
 
Ken, those through connectors were used on a lot of GM stuff in the era. Hie yourself to the local Men's Mall with your cutters and find one or more
sets with the same or more number of connections. Sacrifice one to determine the connector of each sex. Also learn how the connector can be
released from the plug or socket, usually by pressing a tang with a jeweler's screwdriver or equal.
Obtain new connecters and a crimping tool therefor. ONE WIRE AT A TIME replace the contacts on both the plug and socket then remount it. You can
work enough slack in the underhood wires to push the plug into the coach an inch or three.. makes it much easier. A touch of the grease they put on
modern cars and they will go a long time without further ado.

--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" - ol Andy, paraphrased
 
Good advice, Johnny. Fortunately, I've never had any trouble with my fuse
panel, so I'm not in the market for any replacements! :-)

Ken H.

On Wed, Nov 28, 2018 at 1:46 PM Johnny Bridges via Gmclist <

> Ken, those through connectors were used on a lot of GM stuff in the era.
> Hie yourself to the local Men's Mall with your cutters and find one or more
> sets with the same or more number of connections. Sacrifice one to
> determine the connector of each sex. Also learn how the connector can be
> released from the plug or socket, usually by pressing a tang with a
> jeweler's screwdriver or equal.
> Obtain new connecters and a crimping tool therefor. ONE WIRE AT A TIME
> replace the contacts on both the plug and socket then remount it. You can
> work enough slack in the underhood wires to push the plug into the coach
> an inch or three.. makes it much easier. A touch of the grease they put on
> modern cars and they will go a long time without further ado.
>
> --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" - ol Andy, paraphrased
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Depends on how you want to accomplish the task. I used the fuse box from a Chevy pickup and merely spliced it into the existing harness. Crimp, solder
and heat shrink each circuit/wire one at a time. I needed additional circuits and the diesel truck fuse box worked although there always seems to be a
need for more-oil cooler fans, differential oil pumps, electronic fan clutch controls, fuel pumps, parking brake actuators, etc, etc,etc. Additional
aftermarket boxes are available if needed but the factory stuff is just about always good quality and compact. Have fun, Hal
--
1977 Royale 101348,

1977 Royale 101586, Diesel powered,

1975 Eleganza II, 101230,

1974 Eagle Bus 45',w/slideout,

Rio Rancho, NM
 
Ken you left out the Superintendent (9) level :)
I anm toying with the idea of rewiring the chassis setup. As Hal indicates, thins have been added, things have been dropped, it's a mess. I like
chassis mount Molex(tm) plugs. I'm toying with the idea of removing the current setup and installing a modern (blade) fuse holder. Remove the
glovrebox,take the fuse block and socket out, plate the hole, which may need to be enlarged, and fit enough 12 connector Molexes to handle all the
cuircuits, and one or two large Molexes for the heavy current dircuits. Remove the extra wires from the underhood, and rerout the ones still used to
Molex plugs.

--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" - ol Andy, paraphrased
 
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