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| [GMCnet] installing radio [message #132100] |
Sun, 26 June 2011 13:17  |
Dave Motorhome
Messages: 175
Registered: July 2007
Karma: 2
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Senior Member |
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I am installing a radio, the PO made a real mess out of the wiring.
however i was able to use the books and figure out that the yellow 14
gauge wire is hot. the gray 18 gauge wire is ground. however the new
radio says to:
ground to ground
connect yellow to the constant 12 volt power
connect red to be controlled by ignition.
ground is easy, but the other two? it seems to me the yellow 14 gauge
power is constant, what wire is controlled by the ignition?
can i just hook both power to the yellow and just make sure to power
off the radio to stop battery drain?
all help is appreciated!
--
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
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| Re: [GMCnet] installing radio [message #132104 is a reply to message #132100] |
Sun, 26 June 2011 13:45  |
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Hardie Johnson
Messages: 483
Registered: January 2004
Location: Raleigh NC
Karma: 0
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| Dave Motorhome wrote on Sun, 26 June 2011 14:17 |
I am installing a radio, the PO made a real mess out of the wiring however i was able to use the books and figure out that the yellow 14 gauge wire is hot. the gray 18 gauge wire is ground. however the new radio says to:
ground to ground
connect yellow to the constant 12 volt power
connect red to be controlled by ignition.
ground is easy, but the other two? it seems to me the yellow 14 gauge power is constant, what wire is controlled by the ignition?
can i just hook both power to the yellow and just make sure to power off the radio to stop battery drain?
|
The yellow wire is memory, so if you don't mind reprogramming every time you turn it on . . . wire it thru the switch. Just kidding, it is better to have this one hot always, with a fuse, of course.
Crutchfield has a good installation guide.
http://a248.e.akamai.net/pix.crutchfield.com/ca/learningcenter/car/pdfs/receiver_guide.pdf
aka:
http://tinyurl.com/3pjlnt9
Sometimes there is another wire (color?) for an antenna or external amp.
Hopefully you are using the modern, standard DIN box and standard(sort of) wiring plug to make upgrades simpler?
I power my radio and disc changer off the house battery so I can listen while I work on the coach.
"works on it more than he drives it"
Hardie Johnson "Crashj"
1973 26 foot Glacier, White Thing
Raleigh NC
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| Re: [GMCnet] installing radio [message #132106 is a reply to message #132102] |
Sun, 26 June 2011 13:47 |
Dave Motorhome
Messages: 175
Registered: July 2007
Karma: 2
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Senior Member |
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right now the gray wire was just laying in there it was not connected
to anything, but had tape over the end, the PO had installed a
harness, on one side it had a wire that was not connected to anything
but i assumed it was meant to connect to the ground..
i used your pics to navigate, they did help!
http://www.gmcmhphotos.com/photos/showphoto.php?photo=24496&title=here-are-the-spec-s-for-the-radio&cat=4927
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
On Sun, Jun 26, 2011 at 1:37 PM, Mr.erf ERFisher <mr.erfisher@gmail.com> wrote:
> I am sure Emery will jump in here
>
> BUT
>
> the gray wire IS NOT GROUND. it connects to the dash lights and will cause
> many problems if you use it for a ground
>
> gene
>
>
> that the yellow 14
>
>> gauge wire is hot. the gray 18 gauge wire is ground.
>
>
> Gene Fisher -- 74-23,77PB/ore/ca
> “Give a man a fish; you have fed him for today --- give him a URL and
> -------
--
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| Re: [GMCnet] installing radio [message #132109 is a reply to message #132100] |
Sun, 26 June 2011 13:51 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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On Jun 26, 2011, at 12:17 PM, David wrote:
> I am installing a radio, the PO made a real mess out of the wiring.
> however i was able to use the books and figure out that the yellow 14
> gauge wire is hot. the gray 18 gauge wire is ground. however the new
> radio says to:
> ground to ground
> connect yellow to the constant 12 volt power
> connect red to be controlled by ignition.
>
> ground is easy, but the other two? it seems to me the yellow 14 gauge
> power is constant, what wire is controlled by the ignition?
> can i just hook both power to the yellow and just make sure to power
> off the radio to stop battery drain?
>
> all help is appreciated!
>
> --
> David Paliotta
> 75 Glenbrook
> Tulsa, OK
NO! The grey wire is not ground! DO NOT USE IT FOR A GROUND!
Here is something that I had posted back in 2002:
> For anyone putting in a new radio, bear in mind that the GMC original radios used a separate wire for the panel light in the radio so that it could be dimmed when one wanted to dim the dash lights. Not all newer radios use this feature.
>
> There is a grey wire that connected to the original radio for the panel light. If one were to test this wire with the dash lights off, it would appear to be a ground wire as it would ground through several instrument panel light filaments to ground. If this wire is used to connect to the radio ground wire it turns out that the radio will work just fine as the resistance of several bulb filaments in parallel will not put much resistance in the circuit.
>
> The problem is that when the lights are turned on, the current through the dash light fuse is immediately shorted to ground through the radio and will burn out and the dash lights will not work. If anyone is planning to install a new radio you may want to keep this in mind.
>
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: [GMCnet] installing radio [message #132111 is a reply to message #132108] |
Sun, 26 June 2011 14:08 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Emery is right. The grey wire comes from the reostat (variable resistance)
on the headlight switch and it's purpose is to dim the dash and instrument
lighting. Do not use it for a ground. The dash itself is very poorly
grounded in a GMC. When I did my renovation of my instruments, the new
radio, which used a DIN drawer type mount, no longer used the rigid mounting
point that the GMC tape deck radio used for the rear mount. Because it is
firmly attatched to the aluminum back panel, I used it for a binding post,
and grounded all modifications back to it including the radio, tach, vacuum,
trans oil temp, final drive oil temp, etc. That way, if I have a grounding
problem, all I have to do to check it is to slide the radio out of it's
drawer and directly behind it is the common ground binding post.
Incidentally, I also ran a separate ground from there back to the engine
block. It works for me.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sun, Jun 26, 2011 at 11:54 AM, Hardie Johnson <hardie.j@gmail.com> wrote:
>
>
> That gray wire could be speaker ground! There is no reason the chassis
> circuit ground wire would be thinner than the power lead.
> Are you wiring direct to the GMC harness? You may want to run ground wires
> to the speakers instead of relying on chassis ground for them.
> --
> Hardie Johnson "Crashj"
> 1973 26 foot Glacier, White Thing
> Raleigh NC
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| Re: [GMCnet] installing radio [message #132113 is a reply to message #132100] |
Sun, 26 June 2011 14:41 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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On Jun 26, 2011, at 12:55 PM, David wrote:
> i can run a new ground,
> the GMC Yellow seems to be constant 12 volt.
>
> what GMC wire is controlled by ignition?
>
> David Paliotta
> 75 Glenbrook
> Tulsa, OK
David
The original GMC radio used the yellow wire for the 12 volt source. It is powered through the 10 amp radio fuse in the fuse box and you are correct that it is a Batt (battery) lead, not an ACC (accessory) lead. The accessory leads are powered when the ignition switch is on. You could run a new radio lead from the windshield washer switch (that is an ACC 10 volt fused circuit) or from the heater controls. Both of those are hot only when the ignition is on. However, I would suggest that you power it from the house battery instead of from the engine battery. That way you could use the radio when camping without fearing running down the engine battery. To do this just run a lead from the front where you can tie into the solenoid for the house battery which is the large cable going to the back battery. If you do this then be sure to put a fuse into the line that you run to your radio.
The original GMC radio did not have a seperate ground lead. It was grounded through the radio case which was screwed to the metal dash when the radio was mounted.
You could run a ground wire to the metal dash plate and then to your radio.
Emery Stora
> http://75glenbrook.googlepages.com/
>
>
>
>>
>> NO! The grey wire is not ground! DO NOT USE IT FOR A GROUND!
>>
>> Here is something that I had posted back in 2002:
>>
>>> For anyone putting in a new radio, bear in mind that the GMC original radios used a separate wire for the panel light in the radio so that it could be dimmed when one wanted to dim the dash lights. Not all newer radios use this feature.
>>>
>>> There is a grey wire that connected to the original radio for the panel light. If one were to test this wire with the dash lights off, it would appear to be a ground wire as it would ground through several instrument panel light filaments to ground. If this wire is used to connect to the radio ground wire it turns out that the radio will work just fine as the resistance of several bulb filaments in parallel will not put much resistance in the circuit.
>>>
>>> The problem is that when the lights are turned on, the current through the dash light fuse is immediately shorted to ground through the radio and will burn out and the dash lights will not work. If anyone is planning to install a new radio you may want to keep this in mind.
>>>
>>
>> Emery Stora
>> 77 Kingsley
>> Santa Fe, NM
>>
>>
>>
>
>
>
> --
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: [GMCnet] installing radio [message #132118 is a reply to message #132100] |
Sun, 26 June 2011 16:43 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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Yes, it will drain the house battery but extremely slowly. Likewise it will drain the house battery but extremely slowly. The reason that there are two wires is so that the memory chip in the radio receives power all the time so that you don't lose the channels programed into it. Your car also likely has the same setup and you probably have never noticed it draining down the battery.
You can hook both wires to the house battery and then you will be able to play the radio without the ignition being on. My radio has been this way for years and it hss never run down the battery.
Emery Stora
On Jun 26, 2011, at 1:57 PM, David wrote:
> It requires both radio power lines connected. if i attach them to the
> house line does it drain the house battery even if the radio is off?
>
> thanks for eveyones help!
>
> David Paliotta
> 75 Glenbrook
> Tulsa, OK
> http://75glenbrook.googlepages.com/
>
> On Sun, Jun 26, 2011 at 2:41 PM, Emery Stora <emerystora@mac.com> wrote:
>>
>> On Jun 26, 2011, at 12:55 PM, David wrote:
>>
>>> i can run a new ground,
>>> the GMC Yellow seems to be constant 12 volt.
>>>
>>> what GMC wire is controlled by ignition?
>>>
>>> David Paliotta
>>> 75 Glenbrook
>>> Tulsa, OK
>>
>>
>> David
>>
>> The original GMC radio used the yellow wire for the 12 volt source. It is powered through the 10 amp radio fuse in the fuse box and you are correct that it is a Batt (battery) lead, not an ACC (accessory) lead. The accessory leads are powered when the ignition switch is on. You could run a new radio lead from the windshield washer switch (that is an ACC 10 volt fused circuit) or from the heater controls. Both of those are hot only when the ignition is on. However, I would suggest that you power it from the house battery instead of from the engine battery. That way you could use the radio when camping without fearing running down the engine battery. To do this just run a lead from the front where you can tie into the solenoid for the house battery which is the large cable going to the back battery. If you do this then be sure to put a fuse into the line that you run to your radio.
>>
>> The original GMC radio did not have a seperate ground lead. It was grounded through the radio case which was screwed to the metal dash when the radio was mounted.
>>
>> You could run a ground wire to the metal dash plate and then to your radio.
>>
>
> --
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