Black or white?

[boybach]

After finding out the fridge in my coach was wired backwards and blew fuses and diodes every time it was hooked up, I was ready to correct the wiring
problem but wasn't sure whether to swap the 12v feed wires at the fusebox or at the pigtail from the fridge.
Right now, in order to get the fridge running, I connected the pigtail from the control board at the fridge so that the black is positive and the red
is negative ...not an ideal situation so I'd like to sort it out and correct the polarity so future owners won't have to go through what I had to.
This fridge, even though about 10 years old, had NEVER worked. It is basically brand new and now works perfectly.

Question is: What wire coming to the fridge supposed to be + ? Is it the black or the white?

Is that the same system throughout the coach in the 12v system?

TIA

Larry
--
Larry - Victoria BC -

1977 Palm Beach 40,000 miles, PO said everything working but forgot the word NOT. New Atwood fridge, water heater & furnace. New SS exhaust system,
6000w Onan, Iota Converter, R134A A/C, New fuel lines & heat exchange hoses

 

[lawrence belland]

The white wire is universally the "common" wire the black (or any other
color except green) carries the current. Green is the ground. If you ever
see a white wire that looks like it may be carrying power look along the
wire to see if black tape was wrapped around it. You can use a white wire
for power as long as you indicate the change. It should be marked at both
ends.

> After finding out the fridge in my coach was wired backwards and blew
> fuses and diodes every time it was hooked up, I was ready to correct the
> wiring
> problem but wasn't sure whether to swap the 12v feed wires at the fusebox
> or at the pigtail from the fridge.
> Right now, in order to get the fridge running, I connected the pigtail
> from the control board at the fridge so that the black is positive and the
> red
> is negative ...not an ideal situation so I'd like to sort it out and
> correct the polarity so future owners won't have to go through what I had
> to.
> This fridge, even though about 10 years old, had NEVER worked. It is
> basically brand new and now works perfectly.
>
> Question is: What wire coming to the fridge supposed to be + ? Is it the
> black or the white?
>
> Is that the same system throughout the coach in the 12v system?
>
> TIA
>
> Larry
> --
> Larry - Victoria BC -
>
> 1977 Palm Beach 40,000 miles, PO said everything working but forgot the
> word NOT. New Atwood fridge, water heater & furnace. New SS exhaust system,
> 6000w Onan, Iota Converter, R134A A/C, New fuel lines & heat exchange hoses
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

 

[LQQKatJon]

not sure there is a good answer.

usually red should be the + 12v.

but when it comes to some more modern RV stuff, you will find that the black might be + and white ground.

sometimes you need to trace it out. many times you have to pay attention. nice to label for future once you do find out.

http://www.rv-project.com/resources/wirecodes.php#:~:text=Basically%2C%20each%20SOLID%20color%20represents,color%20represents%20a%20different%20circuit.
--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/

 

[Jim Hupy]

Test, test, and verify polarity and voltage. RV's are the worst hodge podge
mess you are likely to ever encounter. A mix of 240 volt AC, 120 voltAC, 12
voly DC. Polarity and color code often wrong. Schematics seldom match
actual conditions.
Jim Hupy
Salem, Oregon

> not sure there is a good answer.
>
> usually red should be the + 12v.
>
> but when it comes to some more modern RV stuff, you will find that the
> black might be + and white ground.
>
> sometimes you need to trace it out. many times you have to pay
> attention. nice to label for future once you do find out.
>
>
>
>
> http://www.rv-project.com/resources/wirecodes.php#:~:text=Basically%2C%20each%20SOLID%20color%20represents,color%20represents%20a%20different%20circuit
> .
> --
> Jon Roche
> 75 palm beach
> EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
> St. Cloud, MN
> http://lqqkatjon.blogspot.com/
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

 

[Stu Rasmussen]

Perusing the DC wiring diagram for my 76 Transmode Birchaven it
appears that BLACK is BATTERY NEGATIVE and goes to FRAME GROUND.

The confusion arises when you think of NEC wiring code for houses,
etc. that specifies white is neutral (common) (also gray can be
neutral) and black is HOT.

So, a prudent sparkie will carefully check what is and what isn't
before inadvertently connecting automotive wiring in the same manner
and color code with house wiring.

Particularly confusing since our coaches have both 12VDC and 120VAC
independent yet interconnected systems.

Stu

Quoting Lawrence Belland :

> The white wire is universally the "common" wire the black (or any other
> color except green) carries the current. Green is the ground. If you ever
> see a white wire that looks like it may be carrying power look along the
> wire to see if black tape was wrapped around it. You can use a white wire
> for power as long as you indicate the change. It should be marked at both
> ends.
>

 

[ghickey]

It seems that some of the automotive industry (maybe a lot) have a
standard convention of using white for ground. Sort of flies in the face
of all the electronics background that I have, but it is what it is. I
have rewired the living area of my coach and replaced everything with
red and black zip cord. So I won't have the problem in the future. There
are a few things that still have white as a ground such as the
replacement marker lights. All of those have white as the ground and
black as +12v. Nothing I can really do about that.

What I would do with your fridge is keep red as +12v but then mark the
white and black wires coming off the fridge as ground and +12v
accordingly. That way the wire coming from the fusebox is still the
polarity that people would expect given the color combination and the
fridge is marked to avoid confusion. Any decent labeler will do a good
job of making tags that you can wrap around each wire to mark them.

--
Gerard Hickey / WTØF IRLP:3067/Echolink:529661
hickey DMR: 3102272
425-395-4554 Allstar: 531920

> After finding out the fridge in my coach was wired backwards and blew fuses and diodes every time it was hooked up, I was ready to correct the wiring
> problem but wasn't sure whether to swap the 12v feed wires at the fusebox or at the pigtail from the fridge.
> Right now, in order to get the fridge running, I connected the pigtail from the control board at the fridge so that the black is positive and the red
> is negative ...not an ideal situation so I'd like to sort it out and correct the polarity so future owners won't have to go through what I had to.
> This fridge, even though about 10 years old, had NEVER worked. It is basically brand new and now works perfectly.
>
> Question is: What wire coming to the fridge supposed to be + ? Is it the black or the white?
>
> Is that the same system throughout the coach in the 12v system?
>
> TIA
>
> Larry

 

[Ken H.]

This thread illustrates exactly why I have my Brother label maker handy any
time I work on GMC wiring. The flag labels I put on every wire I identify
save me a lot of errors and repeated tracing jobs. The Brother is
especially good because the tape comes in multiple colors. The printed
characters are thermally transferred from a black ribbon onto the base
color, then a transparent layer of tape is put on top of that -- all
"automatically" and perfectly. When applied as a "flag" by removing the
protective paper from the adhesive back of the base tape, the label is
there to stay. I've had them under my hood for 20 years with no noticeable
deterioration. Even when I intentionally tested them with a heat gun, the
printing was still legible until the base tape was completely shriveled
around it. And I don't even use the "heavy duty" tape. Can't beat that!

Ken H.

> After finding out the fridge in my coach was wired backwards and blew
> fuses and diodes every time it was hooked up, I was ready to correct the
> wiring
> problem but wasn't sure whether to swap the 12v feed wires at the fusebox
> or at the pigtail from the fridge.
> Right now, in order to get the fridge running, I connected the pigtail
> from the control board at the fridge so that the black is positive and the
> red
> is negative ...not an ideal situation so I'd like to sort it out and
> correct the polarity so future owners won't have to go through what I had
> to.
> This fridge, even though about 10 years old, had NEVER worked. It is
> basically brand new and now works perfectly.
>
> Question is: What wire coming to the fridge supposed to be + ? Is it the
> black or the white?
>
> Is that the same system throughout the coach in the 12v system?
>
> TIA
>
> Larry
> --
> Larry - Victoria BC -
>
> 1977 Palm Beach 40,000 miles, PO said everything working but forgot the
> word NOT. New Atwood fridge, water heater & furnace. New SS exhaust system,
> 6000w Onan, Iota Converter, R134A A/C, New fuel lines & heat exchange hoses
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

 

[Matt Colie]

> This thread illustrates exactly why I have my Brother label maker handy any time I work on GMC wiring. The flag labels I put on every wire I
> identify save me a lot of errors and repeated tracing jobs. The Brother is especially good because the tape comes in multiple colors. The printed
> characters are thermally transferred from a black ribbon onto the base color, then a transparent layer of tape is put on top of that -- all
> "automatically" and perfectly. When applied as a "flag" by removing the protective paper from the adhesive back of the base tape, the label is
> there to stay. I've had them under my hood for 20 years with no noticeable deterioration. Even when I intentionally tested them with a heat gun,
> the
> printing was still legible until the base tape was completely shriveled around it. And I don't even use the "heavy duty" tape. Can't beat
> that!
>
> Ken H.

I very seldom disagree with anything Ken posts. This isn't going to be one of those times.....
The Brother labeler came aboard when I was just about full time doing boat work before the depression set in for the auto industry. I used it to
relabel breaker and switch panels. The grand move there was that the machine I bought can be a printer for a computer. That meant that I could match
the size and font on the existing panels. That was a real score to some owners. One owner almost accused me of not updating his panel....

Shortly after that, I was at a rally at Berrien Springs and I looked under the hood of a coach there and noticed how the owner had used that same
label type to flag just about every wire in evidence. That idea stuck.

A real score to me was that the switch labels on the coach's instrument panel were fading and/or braking up. By going to the laptop (what I had it
connected to) I could create a black background with white letters by reverse printing those labels. Yes, I have tape that make white letters on a
black background, but they are not at all transparent.

Timing was always a bear so, I printed a picture of the timing scale copied right out of the manual and put it on the air filter housing for easy
reference.
When working on the air for the rear suspension, I labeled every one of those plastic air lines and got them back together right on the first try.
I even numbered the spark plug wires. After how many years, so still exist, but they were not a great success everything else has been.

If you are doing serious work or might some day do serious work on your coach, go out and buy a label maker as soon as you can.

There is a very flexible 18mm tape for electric wire labeling. It does not work as well as hoped on most of the GMC sized wires. Big stuff is OK.

If you are ever sitting near Ken, ask him about his friends idea of labeling wires.....

Matt

--
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

 

[mghamms]

I learned to test everything and to expect the unexpected.
When I changed to radio that didn't work when i bought my GMC I don't think any of the wires were correct.
Tested every wire ground + and speaker wires before wiring up the new unit.
--
1977 Kingsley 455 as stock as it gets except lots of Ragusa parts

 

[d c *mac* macdonald]

Marine wiring is moving toward use of red for positive
and yellow for negative in DC wiring.

AC wiring uses black for hot (LINE 1) in 120VAC circuits
and red for the other hot side (LINE 2) in 240VAC circuits
with white being the "common" just as in house wiring.
Green is still safety ground for AC wiring.

D C "Mac" Macdonald
Retired USAF & FAA
Electronic Technician
Oklahoma City, OK
Personally, I recommend using that system for
DC wiring of RVs as well.

Use of this convention can eliminate the confusion
of what "black" signifies.

________________________________
From: stu
Sent: Wednesday, June 16, 2021 12:51
To: gmclist
Subject: [GMCnet] Re: Black or white?

Perusing the DC wiring diagram for my 76 Transmode Birchaven it
appears that BLACK is BATTERY NEGATIVE and goes to FRAME GROUND.

The confusion arises when you think of NEC wiring code for houses,
etc. that specifies white is neutral (common) (also gray can be
neutral) and black is HOT.

So, a prudent sparkie will carefully check what is and what isn't
before inadvertently connecting automotive wiring in the same manner
and color code with house wiring.

Particularly confusing since our coaches have both 12VDC and 120VAC
independent yet interconnected systems.

Stu

Quoting Lawrence Belland :

> The white wire is universally the "common" wire the black (or any other
> color except green) carries the current. Green is the ground. If you ever
> see a white wire that looks like it may be carrying power look along the
> wire to see if black tape was wrapped around it. You can use a white wire
> for power as long as you indicate the change. It should be marked at both
> ends.
>

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:

 

[john r. lebetski]

When it comes to DC and no Red is present all bets are off. That’s why the Evans heater booster fans behind the the stove ran backwards on many GM
coaches.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[Ken H.]

In my X-Birchaven, fitted out by Coachmen, all the DC wiring was White for
Ground and either Blue or Green for +12 VDC. And, I'm almost ashamed
to admit, still is, 'cause the wire was all 10-12 gauge and in excellent
condition, so I reused it when I gutted and rebuilt the interior.

Ken H.

On Wed, Jun 16, 2021 at 7:24 PM John R. Lebetski
wrote:

> When it comes to DC and no Red is present all bets are off. That’s why
> the Evans heater booster fans behind the the stove ran backwards on many GM
> coaches.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

 

[boybach]

So I opened up the pigtail plug and switched the wires there and at the control board. I had some red and black electrical tape and tagged the coach
black and white feed. Job done.

Larry
--
Larry - Victoria BC -

1977 Palm Beach 40,000 miles, PO said everything working but forgot the word NOT. New Atwood fridge, water heater & furnace. New SS exhaust system,
6000w Onan, Iota Converter, R134A A/C, New fuel lines & heat exchange hoses

 

[steve southworth]

As someone said "it depends". I hae found on my early '74:

- The chassis 12v wiring (vehicle related stuff) installed by GM the negative is black. White is a switched wire such as from brake switch to the
turn-signal switch. GM seems to have used some common color codes across the lines. For instance the color codes on the GMCMH are the same as my '75
vette. Get the wiring diagram for your year coach. Get one as large as you can so you can read the small print. If you are not "electrical" the
diagrams are still useable. Think of them like a road map. Follow the "road" to find out where a wire goes, its color. What it connects to will
indicate its function. Color codes are part of this drawing.

- 120VAC GM installed coach wiring follows NEC. That is White is the neutral. Black or Red is hot. green is ground.

- For the coach 12v wiring all bets are off. If your MH coach wiring was installed by GM the wiring diagram for the house wiring will show the color
codes. Do not trust other up-fitters wiring diagrams for color. Test.

After market 12v stuff I have found is relatively consistent. If the leads are red and black then the black is negative. If red and white the white
is negative. Black and white good luck.. One warning that was noted here is things like clearance lights, aisle lights, are not polarity sensitive
and could be wired either way. LED's are polarity sensitive and the correct lead must go to negative. See the note prior note on colors. I have yet
to find one that does not follow this convention.

Basic instruction as noted by others. Don't assume. Always check with a meter. GM did theres their way, up-fitters did it their way. Who knows
what the PO did.

Bottom line is if you have questions ask them here. You will get a correct answer. Maybe more than one.

--
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI