Home » Public Forums » GMCnet » guage lights
| guage lights [message #155981] |
Sun, 08 January 2012 17:56  |
LNelson
Messages: 335
Registered: December 2008
Location: Springfield, MO
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On my recent trip to New Orleans, my first trip in this coach that involved night time driving, when it came time to turn on my lights, my guage lights did not come on. Did they work when I bought the coach...I don't know. Prior to this trip, I did install a new radio (to replace the verklempt OEM radio). Did I do something in that process to make this happen? I will be checking the wiring diagrams tonight. All fuses are good. Thanks.
Larry Nelson Springfield, MO
Ex GMC'er, then GM Busnut
now '77 Eleganza ARS WB0JOT
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| Re: [GMCnet] guage lights [message #155985 is a reply to message #155981] |
Sun, 08 January 2012 18:10  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Larry, if you grounded your radio to the grey wire under the dash, that is
more than likely part of your problem. The grey wire is connected to the
rheostat dimmer for the instrument lighting in the headlight switch. When
it is turned so that it shows maximum resistance, it would appear to be a
ground wire. If you ground the radio to it, your instrument lamps don't
work. Worth a check.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sun, Jan 8, 2012 at 3:56 PM, Larry Nelson <larrynelsonarchitect@mchsi.com
> wrote:
>
>
> On my recent trip to New Orleans, my first trip in this coach that
> involved night time driving, when it came time to turn on my lights, my
> guage lights did not come on. Did they work when I bought the coach...I
> don't know. Prior to this trip, I did install a new radio (to replace the
> verklempt OEM radio). Did I do something in that process to make this
> happen? I will be checking the wiring diagrams tonight. All fuses are good.
> Thanks.
> --
> Springfield, MO
> Ex GMC'er, then GM Busnut
> now '77 Eleganza ARS WB0JOT
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: [GMCnet] guage lights [message #155988 is a reply to message #155981] |
Sun, 08 January 2012 18:15 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Here is something that I posted about 10 years ago and a few times since whenever this problem comes up.
> I had suggested Tuesday that the problem with non-working dash lights might be related to the installation of a new radio. It turns out that Terry's problem was exactly that.
>
> 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 Kingslely
Santa Fe, NM
On Jan 8, 2012, at 4:56 PM, Larry Nelson wrote:
>
>
> On my recent trip to New Orleans, my first trip in this coach that involved night time driving, when it came time to turn on my lights, my guage lights did not come on. Did they work when I bought the coach...I don't know. Prior to this trip, I did install a new radio (to replace the verklempt OEM radio). Did I do something in that process to make this happen? I will be checking the wiring diagrams tonight. All fuses are good. Thanks.
> --
> Springfield, MO
> Ex GMC'er, then GM Busnut
> now '77 Eleganza ARS WB0JOT
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: guage lights [message #156001 is a reply to message #155981] |
Sun, 08 January 2012 19:40 |
LNelson
Messages: 335
Registered: December 2008
Location: Springfield, MO
Karma: 0
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All of my fuses in the fuse block are good. I will check on the grey wire...I see it on the wiring diagram, but would a fuse not blow? Gene, I have wiggled the knob and will wiggle it some more. Thanks to all.
Larry Nelson Springfield, MO
Ex GMC'er, then GM Busnut
now '77 Eleganza ARS WB0JOT
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| Re: [GMCnet] guage lights [message #156037 is a reply to message #156001] |
Mon, 09 January 2012 01:10 |
Chuck Garton
Messages: 54
Registered: June 2006
Karma: 0
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Member |
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The dash lights fuse is fed from the tail lights fuse.
Anytime the dash lights go out, always check for tail lights
especially at night. With the tail lights fuse open, the only outside
lights that will be on will be the headlights.
Chuck Garton
77 Kingsley 455
Ridgecrest, CA
On Sun, Jan 8, 2012 at 5:40 PM, Larry Nelson
<larrynelsonarchitect@mchsi.com> wrote:
>
>
> All of my fuses in the fuse block are good. I will check on the grey wire...I see it on the wiring diagram, but would a fuse not blow? Gene, I have wiggled the knob and will wiggle it some more. Thanks to all.
> --
> Springfield, MO
> Ex GMC'er, then GM Busnut
> now '77 Eleganza ARS WB0JOT
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: guage lights [message #156197 is a reply to message #155981] |
Tue, 10 January 2012 06:01 |
LNelson
Messages: 335
Registered: December 2008
Location: Springfield, MO
Karma: 0
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Senior Member |
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Okay, I have confirmed that my ground wire was the grey wire, and I have replaced that ground with another (real) ground. Now, I still have no dash lights. My manual has a wiring diagram but only the 75-76. The various websites also only go that far. Nothing for the 77 and 78. I assume they are enough alike to keep diagnosing. I still have no dash lights and all of my fuses are good. Now, my next step is to see if there is power at the "instruments" fuse in the block. Also, the wiring diagram shows a "4a Panel Lights" fuse inline with the light switch. Is that the fuse block fuse.....or is it another fuse physically near the switch?
Thanks, as always.
Larry Nelson Springfield, MO
Ex GMC'er, then GM Busnut
now '77 Eleganza ARS WB0JOT
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| Re: [GMCnet] guage lights [message #156199 is a reply to message #156197] |
Tue, 10 January 2012 06:14 |
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Have you liiked at this one?:
From the 1977 / 1978 Maintenance Manual Suppliment on
http://www.bdub.net/wirediagrams/
http://www.bdub.net/wirediagrams/78-chassis-electrolevel-II.gif
bdub
On Tue, Jan 10, 2012 at 6:01 AM, Larry Nelson <
larrynelsonarchitect@mchsi.com> wrote:
>
>
> Okay, I have confirmed that my ground wire was the grey wire, and I have
> replaced that ground with another (real) ground. Now, I still have no dash
> lights. My manual has a wiring diagram but only the 75-76. The various
> websites also only go that far. Nothing for the 77 and 78. I assume they
> are enough alike to keep diagnosing. I still have no dash lights and all of
> my fuses are good. Now, my next step is to see if there is power at the
> "instruments" fuse in the block. Also, the wiring diagram shows a "4a Panel
> Lights" fuse inline with the light switch. Is that the fuse block
> fuse.....or is it another fuse physically near the switch?
>
> Thanks, as always.
> --
> Springfield, MO
> Ex GMC'er, then GM Busnut
> now '77 Eleganza ARS WB0JOT
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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bdub
bdub.net
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| Re: guage lights [message #156217 is a reply to message #155981] |
Tue, 10 January 2012 10:52 |
LNelson
Messages: 335
Registered: December 2008
Location: Springfield, MO
Karma: 0
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Senior Member |
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Okay, I rechecked the little short instrument light fuse and it was kaput.
I replaced it and I now have lights. However, they are either OFF or ON....no dimming capability. Any ideas?
Larry Nelson Springfield, MO
Ex GMC'er, then GM Busnut
now '77 Eleganza ARS WB0JOT
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| Re: [GMCnet] guage lights [message #156218 is a reply to message #156217] |
Tue, 10 January 2012 10:58 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Replace the light switch. The variable resistor (the nichrome wire coiled
looking thing) in the light switch is kaput. Can be tinkered with, but a
new light switch is cheap and readily available. It is a standard GM part
from the 70s/80s. Made by GM Delco, Standard, and a few others.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Tue, Jan 10, 2012 at 8:52 AM, Larry Nelson <
larrynelsonarchitect@mchsi.com> wrote:
>
>
> Okay, I rechecked the little short instrument light fuse and it was kaput.
>
> I replaced it and I now have lights. However, they are either OFF or
> ON....no dimming capability. Any ideas?
> --
> Springfield, MO
> Ex GMC'er, then GM Busnut
> now '77 Eleganza ARS WB0JOT
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] guage lights [message #156221 is a reply to message #156217] |
Tue, 10 January 2012 11:31 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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You may have burned out the variable resistor (wire coil) in the headlight switch.
This switch was used on many GM vehicles for many, many years. It is easy to find at about any auto parts store.
Just ask for an Olds Tornado 1975 head light switch.
To remove it you have to take the switch pull out first. Disconnect your battery cable first. Then pull it way out to the headlight on position and reach under and push the button that is on top (or bottom) of the switch. This will allow you to pull the knob and shaft out of the switch. Then turn the nut on the switch and reaching under the dash and unplug the connector from the switch and pull the switch down and out.
Replacement is just the opposite.
Emery Stora
On Jan 10, 2012, at 9:52 AM, Larry Nelson wrote:
>
>
> Okay, I rechecked the little short instrument light fuse and it was kaput.
>
> I replaced it and I now have lights. However, they are either OFF or ON....no dimming capability. Any ideas?
> --
> Springfield, MO
> Ex GMC'er, then GM Busnut
> now '77 Eleganza ARS WB0JOT
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: guage lights [message #156222 is a reply to message #155981] |
Tue, 10 January 2012 11:39 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Larry,
If you are to replace the headlight switch...here is a photo album by John H that describes the process for a 77....
http://www.gmcmhphotos.com/photos/showgallery.php?cat=4792
Dennis
| LNelson wrote on Sun, 08 January 2012 17:56 |
On my recent trip to New Orleans, my first trip in this coach that involved night time driving, when it came time to turn on my lights, my guage lights did not come on. Did they work when I bought the coach...I don't know. Prior to this trip, I did install a new radio (to replace the verklempt OEM radio). Did I do something in that process to make this happen? I will be checking the wiring diagrams tonight. All fuses are good. Thanks.
|
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] guage lights [message #156266 is a reply to message #156218] |
Tue, 10 January 2012 16:11 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Jim,
IIRC there's a trick to removing the switch or the knob, I can't remember which or what the trick is, can anyone remind me what it
is.
Regards,
Rob M.
-----Original Message-----
From: James Hupy
Replace the light switch. The variable resistor (the nichrome wire coiled
looking thing) in the light switch is kaput. Can be tinkered with, but a
new light switch is cheap and readily available. It is a standard GM part
from the 70s/80s. Made by GM Delco, Standard, and a few others.
Jim
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] guage lights [message #156274 is a reply to message #156266] |
Tue, 10 January 2012 16:31 |
gmcrv1
Messages: 839
Registered: August 2007
Location: Memphis
Karma: -1
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Senior Member |
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Isn't there a small button or detent that has to be depressed to release
the light switch? I'm an old Ford guy - so I may not be correct - refer to
the photo album...
Tom Eckert
On Tue, Jan 10, 2012 at 4:11 PM, Rob Mueller <robmueller@iinet.net.au>wrote:
> Jim,
>
> IIRC there's a trick to removing the switch or the knob, I can't remember
> which or what the trick is, can anyone remind me what it
> is.
>
> Regards,
> Rob M.
>
>
> -----Original Message-----
> From: James Hupy
>
> Replace the light switch. The variable resistor (the nichrome wire coiled
> looking thing) in the light switch is kaput. Can be tinkered with, but a
> new light switch is cheap and readily available. It is a standard GM part
> from the 70s/80s. Made by GM Delco, Standard, and a few others.
> Jim
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] guage lights [message #156275 is a reply to message #156274] |
Tue, 10 January 2012 16:34 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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You guys must not be reading the emails.
Here is something that I posted at 10:31 this morning:
> You may have burned out the variable resistor (wire coil) in the headlight switch.
> This switch was used on many GM vehicles for many, many years. It is easy to find at about any auto parts store.
> Just ask for an Olds Tornado 1975 head light switch.
>
> To remove it you have to take the switch pull out first. Disconnect your battery cable first. Then pull it way out to the headlight on position and reach under and push the button that is on top (or bottom) of the switch. This will allow you to pull the knob and shaft out of the switch. Then turn the nut on the switch and reaching under the dash and unplug the connector from the switch and pull the switch down and out.
>
> Replacement is just the opposite.
>
> Emery Stora
Emery
On Jan 10, 2012, at 3:31 PM, Tom Eckert wrote:
> Isn't there a small button or detent that has to be depressed to release
> the light switch? I'm an old Ford guy - so I may not be correct - refer to
> the photo album...
>
> Tom Eckert
>
>
> On Tue, Jan 10, 2012 at 4:11 PM, Rob Mueller <robmueller@iinet.net.au>wrote:
>
>> Jim,
>>
>> IIRC there's a trick to removing the switch or the knob, I can't remember
>> which or what the trick is, can anyone remind me what it
>> is.
>>
>> Regards,
>> Rob M.
>>
>>
>> -----Original Message-----
>> From: James Hupy
>>
>> Replace the light switch. The variable resistor (the nichrome wire coiled
>> looking thing) in the light switch is kaput. Can be tinkered with, but a
>> new light switch is cheap and readily available. It is a standard GM part
>> from the 70s/80s. Made by GM Delco, Standard, and a few others.
>> Jim
>>
>> _______________________________________________
>> 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
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: [GMCnet] guage lights [message #156279 is a reply to message #156267] |
Tue, 10 January 2012 16:50 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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""Dennis,
Regarding the trick - as Gilda Radner used to say on Saturday Night Live - NEVERMIND!
Regards,
Rob M.
-----Original Message-----
From: Dennis Sexton
Larry,
If you are to replace the headlight switch...here is a photo album by John H that describes the process for a 77....
http://www.gmcmhphotos.com/photos/showgallery.php?cat=4792
Dennis
""
Well there is still a bit of a trick most of the time. On some switches it takes a lot of fiddling and cursing to get that button and the shaft just right before it will disengage.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] guage lights [message #156283 is a reply to message #156222] |
Tue, 10 January 2012 16:56 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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WOW --- GREAT FIND
AND
A GREAT JOB ON THE POST JOHNH
I don't think I saw this before
going on my web site of pointers
thanks
gene
On Tue, Jan 10, 2012 at 9:39 AM, Dennis Sexton <dennisfsexton@aol.com>wrote:
>
>
> Larry,
> If you are to replace the headlight switch...here is a photo album by John
> H that describes the process for a 77....
>
> http://www.gmcmhphotos.com/photos/showgallery.php?cat=4792
>
> Dennis
>
> LNelson wrote on Sun, 08 January 2012 17:56
> > On my recent trip to New Orleans, my first trip in this coach that
> involved night time driving, when it came time to turn on my lights, my
> guage lights did not come on. Did they work when I bought the coach...I
> don't know. Prior to this trip, I did install a new radio (to replace the
> verklempt OEM radio). Did I do something in that process to make this
> happen? I will be checking the wiring diagrams tonight. All fuses are good.
> Thanks.
>
>
> --
> Dennis S
> 73 Painted Desert 230
> Germantown, TN
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
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] guage lights [message #156287 is a reply to message #156283] |
Tue, 10 January 2012 17:29 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Gene,
Yes, John Harper left a nice legacy on the photosite.
I miss him.
Dennis
quote..
WOW --- GREAT FIND
AND
A GREAT JOB ON THE POST JOHNH
I don't think I saw this before
going on my web site of pointers
thanks
gene
end quote....
Dennis S
73 Painted Desert 230
Memphis TN Metro
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