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[GMCnet] Trailer wiring "blue wire" [message #179042] Sun, 05 August 2012 00:00 Go to next message
Dolph Santorine is currently offline  Dolph Santorine   United States
Messages: 1236
Registered: April 2011
Location: Wheeling, WV
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Hi all

My coach has the factory blue wire for trailer brakes.

Where can I find it in the front of the coach?

I see it referenced in a number of threads but no location is mentioned.

Thanks

Dolph Santorine

Dolph@DolphSantorine.com

Excuse me for not being my usual wordy and sporadically verbose self. This message is sent from my iPhone.

No trees were killed in the sending of this message and few long dead dinosaurs were involved. A large number of electrons were terribly inconvenienced.

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Re: [GMCnet] Trailer wiring "blue wire" [message #179054 is a reply to message #179042] Sun, 05 August 2012 07:37 Go to previous messageGo to next message
carguy is currently offline  carguy   United States
Messages: 498
Registered: June 2006
Location: Coshocton OH
Karma: 0
Senior Member

The blue wire is to power electric brakes on the trailer, if present. I don't know where the source of the blue wire is but it may be tied into the wiring that activates the brake lights at the rear.

Bill Brown - '77 Buckeye Cruiser
Coshocton OH
carguybill@sbcglobal.net
Re: [GMCnet] Trailer wiring "blue wire" [message #179055 is a reply to message #179042] Sun, 05 August 2012 07:47 Go to previous messageGo to next message
emerystora is currently offline  emerystora   United States
Messages: 4442
Registered: January 2004
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Senior Member
That wire runs along the inside of the driver's side wall all the way to the front and ends in a multi- wire connector in the panel just above the drivers left knee.

I have seen the connector in the wiring diagram but I don't have the book with me right now.





Emery Stora

On Aug 4, 2012, at 11:00 PM, Dolph Santorine <dolph@dolphsantorine.com> wrote:

> Hi all
>
> My coach has the factory blue wire for trailer brakes.
>
> Where can I find it in the front of the coach?
>
> I see it referenced in a number of threads but no location is mentioned.
>
> Thanks
>
> Dolph Santorine
>
> Dolph@DolphSantorine.com
>
> Excuse me for not being my usual wordy and sporadically verbose self. This message is sent from my iPhone.
>
> No trees were killed in the sending of this message and few long dead dinosaurs were involved. A large number of electrons were terribly inconvenienced.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Re: [GMCnet] Trailer wiring "blue wire" [message #179058 is a reply to message #179042] Sun, 05 August 2012 08:46 Go to previous messageGo to next message
skip2 is currently offline  skip2   United States
Messages: 544
Registered: September 2011
Location: Winter Haven,FL (center o...
Karma: 3
Senior Member
my gmc manual wiring harness page just says "spare wire"
Skip Hartline


74 Canyon Lands, FiTech, 3.7 FD LSD, Manny Tranny, Springfield Distributor, 2001 Chevy Tracker Ragtop Towd

[Updated on: Sun, 05 August 2012 08:47]

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Re: [GMCnet] Trailer wiring "blue wire" [message #179061 is a reply to message #179058] Sun, 05 August 2012 09:41 Go to previous messageGo to next message
Carl S. is currently offline  Carl S.   United States
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
Senior Member

I installed my electric brake controller before I was active in this group. I saw that there was a 'blue wire' in the wiring harness, but I couldn't find it at the front either, so I ran another one from the brake controller to the back. It seemed easier to me although, obviously, not as clean. I ran it under the coach and tied it to the gas lines. It has worked well for four years. If I ever have to redo this, I will attempt to utilize the provided wire.

Carl Stouffer '75 ex Palm Beach Tucson, AZ. Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
[GMCnet] Fwd: Trailer wiring "blue wire" [message #179063 is a reply to message #179055] Sun, 05 August 2012 10:02 Go to previous messageGo to next message
emerystora is currently offline  emerystora   United States
Messages: 4442
Registered: January 2004
Karma: 13
Senior Member
More information on that "blue wire".
Look for a six wire connector tucked behind the left panel just under the dash to the driver's left side. It has a yellow wire which is the left hand stop and directional light, a dark green which is the right hand stop and directional, a brown which is the stop lights, a white which is the trailer ground and the light blue (extra wire).

This all is called the trailer wiring RPO in the wiring diagrams.

I will look in the GMC assembly book when I get back home and can perhaps give more definite directions on when the connector is.

Emery Stora

Begin forwarded message

> From: Emery Stora <emerystora@mac.com>
> Subject: Re: [GMCnet] Trailer wiring "blue wire"
> Date: August 5, 2012 6:47:59 AM MDT
> To: "gmclist@temp.gmcnet.org" <gmclist@temp.gmcnet.org>
> Bcc: Emery Stora <emerystora@mac.com>
>
> That wire runs along the inside of the driver's side wall all the way to the front and ends in a multi- wire connector in the panel just above the drivers left knee.
>
> I have seen the connector in the wiring diagram but I don't have the book with me right now.
>
>
>
>
>
> Emery Stora
>
> On Aug 4, 2012, at 11:00 PM, Dolph Santorine <dolph@dolphsantorine.com> wrote:
>
>> Hi all
>>
>> My coach has the factory blue wire for trailer brakes.
>>
>> Where can I find it in the front of the coach?
>>
>> I see it referenced in a number of threads but no location is mentioned.
>>
>> Thanks
>>
>> Dolph Santorine
>>
>> Dolph@DolphSantorine.com
>>
>> Excuse me for not being my usual wordy and sporadically verbose self. This message is sent from my iPhone.
>>
>> No trees were killed in the sending of this message and few long dead dinosaurs were involved. A large number of electrons were terribly inconvenienced.
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

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Re: [GMCnet] Trailer wiring "blue wire" [message #180306 is a reply to message #179042] Tue, 14 August 2012 22:44 Go to previous messageGo to next message
Gerald Wheeler is currently offline  Gerald Wheeler   United States
Messages: 152
Registered: February 2004
Karma: 0
Senior Member

Speaking of blue wires, I have the blues as I am having problems with my
daughter's coach towing wiring. I have tested my daughter's towd wiring
system with my coach and all lights work correctly (brakes, turn signals,
etc). But plugged into her coach, a number of things happen. With the
coach lights off, both turn signals work and the proper filaments light up.
But the other bulb filament lights when the brakes are applied (should be
same filament). With the coach lights on, the turn signal lights the
wrong filament (not the same filament when the coach lights are off) and
the other towd light flashes too. I won't list the other combinations
that don't work properly. What I need to know is where I should tap into
the coach wiring system to run all NEW wires for the towing lights?? Would
also like to know where to hook a blue wire for trailer brakes. All
suggestions are appreciated.

JR Wheeler NC/OR



> [Original Message]
> From: Bill Brown <carguybill@sbcglobal.net>
> To: <gmclist@temp.gmcnet.org>
> Date: 8/5/2012 5:37:37 AM
> Subject: Re: [GMCnet] Trailer wiring "blue wire"
>
>
>
> The blue wire is to power electric brakes on the trailer, if present. I
don't know where the source of the blue wire is but it may be tied into the
wiring that activates the brake lights at the rear.
> --
> Bill Brown - '77 Buckeye Cruiser
> Coshocton OH
> carguybill@sbcglobal.net
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2012.0.2197 / Virus Database: 2437/5178 - Release Date: 08/04/12


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Re: [GMCnet] Trailer wiring "blue wire" [message #180308 is a reply to message #180306] Tue, 14 August 2012 22:59 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
Messages: 6806
Registered: May 2010
Karma: -62
Senior Member
JR, ALWAYS establish a good ground between the two vehicles before you do
anything else. That is the source of more problems with trailer connections
than anything I can think of. They will back feed and cross feed if you
don't have a good ground.
Jim Hupy
Salem, OR
78 GMC Royale 403

On Tue, Aug 14, 2012 at 8:44 PM, Gerald Wheeler <jrwheeler7@earthlink.net>wrote:

>
> Speaking of blue wires, I have the blues as I am having problems with my
> daughter's coach towing wiring. I have tested my daughter's towd wiring
> system with my coach and all lights work correctly (brakes, turn signals,
> etc). But plugged into her coach, a number of things happen. With the
> coach lights off, both turn signals work and the proper filaments light up.
> But the other bulb filament lights when the brakes are applied (should be
> same filament). With the coach lights on, the turn signal lights the
> wrong filament (not the same filament when the coach lights are off) and
> the other towd light flashes too. I won't list the other combinations
> that don't work properly. What I need to know is where I should tap into
> the coach wiring system to run all NEW wires for the towing lights?? Would
> also like to know where to hook a blue wire for trailer brakes. All
> suggestions are appreciated.
>
> JR Wheeler NC/OR
>
>
>
> > [Original Message]
> > From: Bill Brown <carguybill@sbcglobal.net>
> > To: <gmclist@temp.gmcnet.org>
> > Date: 8/5/2012 5:37:37 AM
> > Subject: Re: [GMCnet] Trailer wiring "blue wire"
> >
> >
> >
> > The blue wire is to power electric brakes on the trailer, if present. I
> don't know where the source of the blue wire is but it may be tied into the
> wiring that activates the brake lights at the rear.
> > --
> > Bill Brown - '77 Buckeye Cruiser
> > Coshocton OH
> > carguybill@sbcglobal.net
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >
> >
> > -----
> > No virus found in this message.
> > Checked by AVG - www.avg.com
> > Version: 2012.0.2197 / Virus Database: 2437/5178 - Release Date: 08/04/12
>
>
> _______________________________________________
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>
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Re: [GMCnet] Trailer wiring "blue wire" [message #180309 is a reply to message #180308] Tue, 14 August 2012 23:26 Go to previous messageGo to next message
John Sharpe is currently offline  John Sharpe   United States
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
Senior Member
Quote:

JR, ALWAYS establish a good ground between the two vehicles before you do
anything else. That is the source of more problems with trailer connections
than anything I can think of. They will back feed and cross feed if you
don't have a good ground.
Jim Hupy
Salem, OR
78 GMC Royale 403


Jim I concur. It's a ground problem.


John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
Re: [GMCnet] Trailer wiring "blue wire" [message #180310 is a reply to message #180306] Tue, 14 August 2012 23:49 Go to previous messageGo to next message
mickeysss is currently offline  mickeysss   United States
Messages: 1476
Registered: January 2012
Karma: 0
Senior Member

when in doubt go to u haul and give them 20 bucks for wiring.

i also get these bulbs from uhaul that two wires hang out side the lens from the bulbs you buy and then you

just plug into the bulbs if you know what i mean. they sell them there. piggy back bulbs and connections.

sort of an emergency design only but i put one in 10 years ago for a boat and never changed them.

mick
77 palm beach
disneyland ca.


On Aug 14, 2012, at 8:44 PM, Gerald Wheeler wrote:

>
> Speaking of blue wires, I have the blues as I am having problems with my
> daughter's coach towing wiring. I have tested my daughter's towd wiring
> system with my coach and all lights work correctly (brakes, turn signals,
> etc). But plugged into her coach, a number of things happen. With the
> coach lights off, both turn signals work and the proper filaments light up.
> But the other bulb filament lights when the brakes are applied (should be
> same filament). With the coach lights on, the turn signal lights the
> wrong filament (not the same filament when the coach lights are off) and
> the other towd light flashes too. I won't list the other combinations
> that don't work properly. What I need to know is where I should tap into
> the coach wiring system to run all NEW wires for the towing lights?? Would
> also like to know where to hook a blue wire for trailer brakes. All
> suggestions are appreciated.
>
> JR Wheeler NC/OR
>
>
>
>> [Original Message]
>> From: Bill Brown <carguybill@sbcglobal.net>
>> To: <gmclist@temp.gmcnet.org>
>> Date: 8/5/2012 5:37:37 AM
>> Subject: Re: [GMCnet] Trailer wiring "blue wire"
>>
>>
>>
>> The blue wire is to power electric brakes on the trailer, if present. I
> don't know where the source of the blue wire is but it may be tied into the
> wiring that activates the brake lights at the rear.
>> --
>> Bill Brown - '77 Buckeye Cruiser
>> Coshocton OH
>> carguybill@sbcglobal.net
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2012.0.2197 / Virus Database: 2437/5178 - Release Date: 08/04/12
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Re: [GMCnet] Trailer wiring "blue wire" [message #180320 is a reply to message #179042] Wed, 15 August 2012 00:24 Go to previous messageGo to next message
Gerald Wheeler is currently offline  Gerald Wheeler   United States
Messages: 152
Registered: February 2004
Karma: 0
Senior Member

This coach had some wires hanging near the bumper, all taped up, which I
assumed was for towd/trailer. I unwrapped them and tested each wire
individually for all functions, identifying which wire did what with a
single test bulb. I had purchased many years ago a standard towd/trailer
magnetic running light set; 30' of wire, 6 pin connector with four wires:
white ground, green rt turn, yellow left turn, brown running lights. I
took the plug apart to make sure they were wired in the correct positions.
I installed Merrill's thru the bumper hitch and installed a 6 pin connector
using the wires I identified thru testing on the coach. I wired the coach
connector correctly to mate with the towd/trailer connector. Since the
towd/trailer system tested properly with my coach, the problem has to be
with the wiring in my daughter's coach. I actually used two different
ground wires. I'll remove the coach ground wire (as determined by my
testing) and use only the ground wire I put in. Perhaps that coach
ground wire is doing something funny. I'll report back tomorrow. The
GMC guru Gene Fisher along with Gary Bovee are dropping by tomorrow, so
maybe they will have some ideas. Report around 3pm PST.

JR Wheeler NC/OR



> [Original Message]
> From: James Hupy <jamesh1296@gmail.com>
> To: <gmclist@temp.gmcnet.org>
> Date: 8/14/2012 8:59:22 PM
> Subject: Re: [GMCnet] Trailer wiring "blue wire"
>
> JR, ALWAYS establish a good ground between the two vehicles before you do
> anything else. That is the source of more problems with trailer
connections
> than anything I can think of. They will back feed and cross feed if you
> don't have a good ground.
> Jim Hupy
> Salem, OR
> 78 GMC Royale 403
>
> On Tue, Aug 14, 2012 at 8:44 PM, Gerald Wheeler
<jrwheeler7@earthlink.net>wrote:
>
> >
> > Speaking of blue wires, I have the blues as I am having problems with my
> > daughter's coach towing wiring. I have tested my daughter's towd
wiring
> > system with my coach and all lights work correctly (brakes, turn
signals,
> > etc). But plugged into her coach, a number of things happen. With the
> > coach lights off, both turn signals work and the proper filaments light
up.
> > But the other bulb filament lights when the brakes are applied (should
be
> > same filament). With the coach lights on, the turn signal lights the
> > wrong filament (not the same filament when the coach lights are off) and
> > the other towd light flashes too. I won't list the other combinations
> > that don't work properly. What I need to know is where I should tap
into
> > the coach wiring system to run all NEW wires for the towing lights??
Would
> > also like to know where to hook a blue wire for trailer brakes. All
> > suggestions are appreciated.
> >
> > JR Wheeler NC/OR
> >
> >
> >
> > > [Original Message]
> > > From: Bill Brown <carguybill@sbcglobal.net>
> > > To: <gmclist@temp.gmcnet.org>
> > > Date: 8/5/2012 5:37:37 AM
> > > Subject: Re: [GMCnet] Trailer wiring "blue wire"
> > >
> > >
> > >
> > > The blue wire is to power electric brakes on the trailer, if present.
I
> > don't know where the source of the blue wire is but it may be tied into
the
> > wiring that activates the brake lights at the rear.
> > > --
> > > Bill Brown - '77 Buckeye Cruiser
> > > Coshocton OH
> > > carguybill@sbcglobal.net
> > > _______________________________________________
> > > GMCnet mailing list
> > > Unsubscribe or Change List Options:
> > > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> > >
> > >
> > > -----
> > > No virus found in this message.
> > > Checked by AVG - www.avg.com
> > > Version: 2012.0.2197 / Virus Database: 2437/5178 - Release Date:
08/04/12
> >
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2012.0.2197 / Virus Database: 2437/5201 - Release Date: 08/14/12


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Re: [GMCnet] Trailer wiring "blue wire" [message #180322 is a reply to message #180309] Wed, 15 August 2012 00:36 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
Senior Member
John Sharpe wrote on Tue, 14 August 2012 23:26

Quote:

JR, ALWAYS establish a good ground between the two vehicles before you do
anything else. That is the source of more problems with trailer connections
than anything I can think of. They will back feed and cross feed if you
don't have a good ground.
Jim Hupy
Salem, OR
78 GMC Royale 403


Jim I concur. It's a ground problem.


That was my first thought also.

Grab a set of jumper cables. Connect one to the steel bumpers of the towing vehicle and the towd. If the lights work correctly then you will know that you need to correct the ground connections.

What kind of vehicle are you towing? I am assuming that the towing vehicle is a GMC.




Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: [GMCnet] Trailer wiring "blue wire" [message #180329 is a reply to message #180306] Wed, 15 August 2012 06:31 Go to previous messageGo to next message
Steven Ferguson is currently offline  Steven Ferguson   United States
Messages: 3447
Registered: May 2006
Karma: 0
Senior Member
http://www.harborfreight.com/four-way-trailer-light-tester-66526.html or
http://www.tlt-tool.com/

Or, the best I have found so far are the wireless, magnetic base lights.
Pay once, easily xferable from vehicle to vehicle or to a trailer. NO
connections and they are extremely bright. I use rechargeable batteries
(Sony Eneloop are the industry leaders) and I keep a charger in the coach.
Batteries last well over 24 towing hours.

On Tue, Aug 14, 2012 at 8:44 PM, Gerald Wheeler <jrwheeler7@earthlink.net>wrote:

>
> Speaking of blue wires, I have the blues as I am having problems with my
> daughter's coach towing wiring. I have tested my daughter's towd wiring
> system with my coach and all lights work correctly (brakes, turn signals,
> etc). But plugged into her coach, a number of things happen. With the
> coach lights off, both turn signals work and the proper filaments light up.
> But the other bulb filament lights when the brakes are applied (should be
> same filament). With the coach lights on, the turn signal lights the
> wrong filament (not the same filament when the coach lights are off) and
> the other towd light flashes too. I won't list the other combinations
> that don't work properly. What I need to know is where I should tap into
> the coach wiring system to run all NEW wires for the towing lights?? Would
> also like to know where to hook a blue wire for trailer brakes. All
> suggestions are appreciated.
>
> JR Wheeler NC/OR
>
>
>
> > [Original Message]
> > From: Bill Brown <carguybill@sbcglobal.net>
> > To: <gmclist@temp.gmcnet.org>
> > Date: 8/5/2012 5:37:37 AM
> > Subject: Re: [GMCnet] Trailer wiring "blue wire"
> >
> >
> >
> > The blue wire is to power electric brakes on the trailer, if present. I
> don't know where the source of the blue wire is but it may be tied into the
> wiring that activates the brake lights at the rear.
> > --
> > Bill Brown - '77 Buckeye Cruiser
> > Coshocton OH
> > carguybill@sbcglobal.net
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >
> >
> > -----
> > No virus found in this message.
> > Checked by AVG - www.avg.com
> > Version: 2012.0.2197 / Virus Database: 2437/5178 - Release Date: 08/04/12
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>



--
Fathom the hypocrisy of a nation where every citizen must prove they have
health insurance......but not everyone has to prove they're a citizen.
Steve Ferguson
Sierra Vista, AZ
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Re: [GMCnet] Trailer wiring "blue wire" [message #180341 is a reply to message #179042] Wed, 15 August 2012 08:35 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
Senior Member
I'm not going to quote all of what Jerry wrote.

Jerry,

Trust everybody. Don't bother digging into the daughter's coach to fix this. When you have done KenB's jumper cable test to prove it is a ground issue, then run a new clean ground from the screw you just put in the frame into your trailer connector.

I have seen this so very times in boat trailers, I can't even guess at a count.

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
Re: [GMCnet] Trailer wiring "blue wire" [message #180342 is a reply to message #180320] Wed, 15 August 2012 09:03 Go to previous messageGo to next message
Mr ERFisher is currently offline  Mr ERFisher   United States
Messages: 7117
Registered: August 2005
Karma: 2
Senior Member
Gene Fisher along with Gary Bovee are dropping by tomorrow, so

> maybe they will have some ideas. Report around 3pm PST.
>
>
will bring the
test light
meter
8X10 glossy photos ( well maybe charged iPod)

see you bout noon

gene

--
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] Trailer wiring "blue wire" [message #180383 is a reply to message #179042] Wed, 15 August 2012 14:21 Go to previous messageGo to next message
Gerald Wheeler is currently offline  Gerald Wheeler   United States
Messages: 152
Registered: February 2004
Karma: 0
Senior Member

I'll report back tomorrow. The
GMC guru Gene Fisher along with Gary Bovee are dropping by tomorrow, so
maybe they will have some ideas. Report around 3pm PST.

Gene Fisher and Gary Bovee came early and Gene was able to solve my
problem. It was a grounding problem as several of you suggested; but one
that I would never have thought of. I installed a new 6 pin round plug on
my daughter's coach. All wires were attached correctly to the male and
female plugs. The ground wire was connected to the frame properly. What
it turned out to be was the male pin on the new 6 pin round connector was
making intermittent contact with the female receptacle ( the sides of the
male pin didn't touch the sides of the female receptacle). Problem was
solved by spreading the ends of that male pin of the new plug. When I
tested the towd/trailer light assembly with my other coach, the plugs mated
properly and the lights worked. I would have bet good dollars that
grounding was not the problem given the number of wires the coach had
available for towd/trailer towing. Thanks again Gene Fisher.

JR Wheeler NC/OR



> [Original Message]
> From: Gerald Wheeler <jrwheeler7@earthlink.net>
> To: <gmclist@temp.gmcnet.org>
> Date: 8/14/2012 10:24:31 PM
> Subject: Re: [GMCnet] Trailer wiring "blue wire"
>
>
> This coach had some wires hanging near the bumper, all taped up, which I
> assumed was for towd/trailer. I unwrapped them and tested each wire
> individually for all functions, identifying which wire did what with a
> single test bulb. I had purchased many years ago a standard towd/trailer
> magnetic running light set; 30' of wire, 6 pin connector with four wires:
> white ground, green rt turn, yellow left turn, brown running lights. I
> took the plug apart to make sure they were wired in the correct
positions.
> I installed Merrill's thru the bumper hitch and installed a 6 pin
connector
> using the wires I identified thru testing on the coach. I wired the
coach
> connector correctly to mate with the towd/trailer connector. Since the
> towd/trailer system tested properly with my coach, the problem has to be
> with the wiring in my daughter's coach. I actually used two different
> ground wires. I'll remove the coach ground wire (as determined by my
> testing) and use only the ground wire I put in. Perhaps that coach
> ground wire is doing something funny. I'll report back tomorrow. The
> GMC guru Gene Fisher along with Gary Bovee are dropping by tomorrow, so
> maybe they will have some ideas. Report around 3pm PST.
>
> JR Wheeler NC/OR
>
>
>
> > [Original Message]
> > From: James Hupy <jamesh1296@gmail.com>
> > To: <gmclist@temp.gmcnet.org>
> > Date: 8/14/2012 8:59:22 PM
> > Subject: Re: [GMCnet] Trailer wiring "blue wire"
> >
> > JR, ALWAYS establish a good ground between the two vehicles before you
do
> > anything else. That is the source of more problems with trailer
> connections
> > than anything I can think of. They will back feed and cross feed if you
> > don't have a good ground.
> > Jim Hupy
> > Salem, OR
> > 78 GMC Royale 403
> >
> > On Tue, Aug 14, 2012 at 8:44 PM, Gerald Wheeler
> <jrwheeler7@earthlink.net>wrote:
> >
> > >
> > > Speaking of blue wires, I have the blues as I am having problems with
my
> > > daughter's coach towing wiring. I have tested my daughter's towd
> wiring
> > > system with my coach and all lights work correctly (brakes, turn
> signals,
> > > etc). But plugged into her coach, a number of things happen. With
the
> > > coach lights off, both turn signals work and the proper filaments
light
> up.
> > > But the other bulb filament lights when the brakes are applied (should
> be
> > > same filament). With the coach lights on, the turn signal lights the
> > > wrong filament (not the same filament when the coach lights are off)
and
> > > the other towd light flashes too. I won't list the other
combinations
> > > that don't work properly. What I need to know is where I should tap
> into
> > > the coach wiring system to run all NEW wires for the towing lights??
> Would
> > > also like to know where to hook a blue wire for trailer brakes. All
> > > suggestions are appreciated.
> > >
> > > JR Wheeler NC/OR
> > >
> > >
> > >
> > > > [Original Message]
> > > > From: Bill Brown <carguybill@sbcglobal.net>
> > > > To: <gmclist@temp.gmcnet.org>
> > > > Date: 8/5/2012 5:37:37 AM
> > > > Subject: Re: [GMCnet] Trailer wiring "blue wire"
> > > >
> > > >
> > > >
> > > > The blue wire is to power electric brakes on the trailer, if
present.
> I
> > > don't know where the source of the blue wire is but it may be tied
into
> the
> > > wiring that activates the brake lights at the rear.
> > > > --
> > > > Bill Brown - '77 Buckeye Cruiser
> > > > Coshocton OH
> > > > carguybill@sbcglobal.net
> > > > _______________________________________________
> > > > GMCnet mailing list
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> > > >
> > > >
> > > > -----
> > > > No virus found in this message.
> > > > Checked by AVG - www.avg.com
> > > > Version: 2012.0.2197 / Virus Database: 2437/5178 - Release Date:
> 08/04/12
> > >
> > >
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Re: [GMCnet] Trailer wiring "blue wire" [message #180396 is a reply to message #179042] Wed, 15 August 2012 16:10 Go to previous messageGo to next message
zhagrieb is currently offline  zhagrieb   United States
Messages: 676
Registered: August 2009
Location: Portland Oregon
Karma: 0
Senior Member
Dolph,

If yours is an early coach the blue wire may go nowhere.

Glenn


Glenn Giere, Portland OR, K7GAG '73 "Moby the Motorhome" 26'
Re: [GMCnet] Trailer wiring "blue wire" [message #180427 is a reply to message #179042] Wed, 15 August 2012 20:23 Go to previous messageGo to next message
tphipps is currently offline  tphipps   United States
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
Senior Member
Can the blue wire be used to fire up a 3rd brake light? Hate to reinvent something, if it is already there.
Tom, MS I I


2012 Phoenix Cruiser model 2552 KA4CSG
Re: [GMCnet] Trailer wiring "blue wire" [message #180436 is a reply to message #180427] Wed, 15 August 2012 21:06 Go to previous messageGo to next message
midlf is currently offline  midlf   United States
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
Senior Member
tphipps wrote on Wed, 15 August 2012 20:23

Can the blue wire be used to fire up a 3rd brake light? Hate to reinvent something, if it is already there.
Tom, MS I I


Yes - if you can find the head end of it. Some have reported this is difficult. I haven't found mine yet. I want to use it, as intended, for electric brakes.


Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
Re: [GMCnet] Trailer wiring "blue wire" [message #180438 is a reply to message #180427] Wed, 15 August 2012 21:13 Go to previous messageGo to previous message
Matt Colie is currently offline  Matt Colie   United States
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
Senior Member
tphipps wrote on Wed, 15 August 2012 21:23

Can the blue wire be used to fire up a 3rd brake light? Hate to reinvent something, if it is already there.
Tom, MS I I

Tom,

Emery says that it runs up to the side panel by the driver's left. That may be, but I can't find mine - even with a good RF wire tracker.

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
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