| [GMCnet] Electrical question [message #68457] |
Sun, 27 December 2009 10:16  |
Kim David McNeill Sim
Messages: 26
Registered: May 2008
Karma: 0
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I have to apologize for asking about this upfront as I know this has been covered not all that long ago.
Seems with a little tightening up of wiring we just did I seem to have lost my headlights and right turn signal, bulbs are Ok, and to complicate matters when I pull the headlight switch I lose the PO added tach, even though no headlights at all.
So before I dive into all of this electrical mess I am hoping someone as I have seen it, might have the electrical schematic on the '76 Eleganza II.
I am thinking the PO did some strange wiring for the tach that involves the headlight switch- why else would this be happening? But I am not sure that will explain the turn signal.
Also I did notice the tail lights are just not very bright, but I also remember reading that new upgraded lights can be used as replacements, Anyone know what they are and what would be involved? I am not interested in adding a third tail light.
I also noticed today that my electric switches to the air pumps for the airbags seem to need some attention as well- I am sure there is a solution for that as well, because I have seen it some place on this forum.
I had thought I had saved these diagrams and information someplace, but I must have misplaced the information.
Thank you
Kim
Kim and Pat Simmons
'76 Eleganza II
New Richmond, Ohio
TZE166V101526
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| Re: [GMCnet] Electrical question [message #68469 is a reply to message #68457] |
Sun, 27 December 2009 11:25  |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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I'd say you have a poor connection supplying power to the headlights and the PO has connected the Tach to the power lead for the headlight switch. When you pull on the headlight switch, the load of the headlights pulls the voltage way down to near Zero volts because of a bad connection. Therefore, no headlights and no Tach.
According to my Electrical diagram for 1976, the power to the Headlight switch comes from the main power terminal on the Horn Relay under the right front hood. The power for the turn signals come on a separate wire to the Bat bus bar in the fuse panel. The only common point is the main battery connection on the Horn relay, or the fusable link supplying the power to that point. However if it was the fusable link, the entire coach front would appear dead as it supplies all power to the dash, ign switch etc.
BTW, has anyone ever had that fusable link go bad??
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: [GMCnet] Electrical question/ Fusable link [message #68487 is a reply to message #68469] |
Sun, 27 December 2009 13:26 |
Nelson Wright
Messages: 147
Registered: May 2004
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Has anyone had that go bad?? The answer is yes, and sometimes it's not
a pretty thing, as prior to actually burning itself out it has shorted
out many other things in the dash wiring harness. I would not replace
it with another piece of fusable wire, but make up a replacement wire
with a fuse in line. Call Jim Bounds at the Coop, he has an
inexpensive kit to rectify this problem.
HTH,
Nelson Wright
Orlando, Fl.
On Dec 27, 2009, at 12:25 PM, Bruce Hislop wrote:
>
>
> BTW, has anyone ever had that fusable link go bad??
> --
> Bruce Hislop,
> S. Ontario Canada
> 77PB, 455
> http://www.gmcmhphotos.com/photos/showgallery.php?cat=500&ppuser=1906
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| Re: [GMCnet] Electrical question [message #68518 is a reply to message #68469] |
Sun, 27 December 2009 16:13 |
Kim David McNeill Sim
Messages: 26
Registered: May 2008
Karma: 0
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Bruce,
Thank you for the suggestions, kind of what I was thinking but then when it comes to my GMC electrical "stuff" I guess I am somewhat afraid to do anything because of this kind of problem cropping up.
I have power everywhere but headlights or tach so I think the fusable link is OK.
I do have the upgraded headlights which now run ( I think power directly from battery) but it still uses the switch to turn them on and off. So I am going to assume the same logic applies, bad connection somewhere.
Of course I have not tried the horn to se if it works, not even sure if I have ever used the horn on the GMC.
On the turn signal issue, since I have a left turn signal could a problem be somewhere else "down the line"?
Thank you again
Kim
Kim and Pat Simmons
'76 Eleganza II
New Richmond, Ohio
On Dec 27, 2009, at 12:25 PM, Bruce Hislop wrote:
>
>
> I'd say you have a poor connection supplying power to the headlights and the PO has connected the Tach to the power lead for the headlight switch. When you pull on the headlight switch, the load of the headlights pulls the voltage way down to near Zero volts because of a bad connection. Therefore, no headlights and no Tach.
> According to my Electrical diagram for 1976, the power to the Headlight switch comes from the main power terminal on the Horn Relay under the right front hood. The power for the turn signals come on a separate wire to the Bat bus bar in the fuse panel. The only common point is the main battery connection on the Horn relay, or the fusable link supplying the power to that point. However if it was the fusable link, the entire coach front would appear dead as it supplies all power to the dash, ign switch etc.
>
> BTW, has anyone ever had that fusable link go bad??
> --
> Bruce Hislop,
> S. Ontario Canada
> 77PB, 455
> http://www.gmcmhphotos.com/photos/showgallery.php?cat=500&ppuser=1906
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Electrical question [message #68519 is a reply to message #68518] |
Sun, 27 December 2009 16:25 |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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Senior Member |
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I am thinking a bad ground might be part of your problem. I had same issue with tach on my vdub. Pull headlights on and tach quit. Was grounding issue. I knew my tach did not depend on the headlight switch because I installed it and did all the wiring myself on the vdub. On the headlights, get your voltmeter out. You can not fix this without properly diagnosing it. Don't forget to check your wiring to and from the dimmer switch. I would start at the headlights and work backwards. You can find it and fix it yourself. Make sure you report back to us what you are finding. I am no real mechanic, or wiring expert, but we have some on here so they will get you fixed up.
Dan
roscoe, tx.
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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