| A "Short" Question [message #93700] |
Wed, 28 July 2010 18:58  |
Dave Wilson
Messages: 94
Registered: September 2009
Location: Livonia, MI
Karma: 0
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Hi Everyone,
Recently our GMC developed a short lurking somewhere in the vehicle, I'm guessing the instrument panel. When I shift into Drive, the heater/AC cluster light comes on (the illumination light). Also, when the headlights are turned on, in Drive again, the front overhead clearance lights go out. Those same clearance lights stay on in Nuetral. Finally, when I shift into Drive, the "Set Power Level to Auto" light comes on; when I click the power level into "Auto", the idiot light stays dimly lit in the background. I can make it turn off by moving the gear selector closer to Nuetral while still staying in Drive. These different occurences may all be their own problems, or as I suspect they all may be related. I don't know where to look specifically, or how to eliminate each area. If anyone can offer ideas where to look or other advice, I would greatly appreciate it! Thanks for any suggestions.
Dave Wilson
'77 Eleganza II
Photos @ http://www.gmcmhphotos.com/photos/member.php?uid=2183&protype=1
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| Re: A "Short" Question [message #93702 is a reply to message #93700] |
Wed, 28 July 2010 19:15  |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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| Dave Wilson wrote on Wed, 28 July 2010 19:58 |
Hi Everyone,
Recently our GMC developed a short lurking somewhere in the vehicle, I'm guessing the instrument panel. When I shift into Drive, the heater/AC cluster light comes on (the illumination light). Also, when the headlights are turned on, in Drive again, the front overhead clearance lights go out. Those same clearance lights stay on in Nuetral. Finally, when I shift into Drive, the "Set Power Level to Auto" light comes on; when I click the power level into "Auto", the idiot light stays dimly lit in the background. I can make it turn off by moving the gear selector closer to Nuetral while still staying in Drive. These different occurences may all be their own problems, or as I suspect they all may be related. I don't know where to look specifically, or how to eliminate each area. If anyone can offer ideas where to look or other advice, I would greatly appreciate it! Thanks for any suggestions.
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Sir: have you "fixed" anything electrical lately? Maybe unplug the neutral safety switch on the bottom of the column and see if anything changes.
Good luck
C. Boyd
76 Crestmont
East Tennessee
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| Re: A "Short" Question [message #93705 is a reply to message #93702] |
Wed, 28 July 2010 19:30 |
Dave Wilson
Messages: 94
Registered: September 2009
Location: Livonia, MI
Karma: 0
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| C Boyd wrote on Wed, 28 July 2010 19:15 |
Sir: have you "fixed" anything electrical lately? Maybe unplug the neutral safety switch on the bottom of the column and see if anything changes.
Good luck
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About two years ago I put in a radio and the fiberoptic dash panel lights. Everything worked fine until late June of this year....(and yes, I have had the panel off the back of the IP before writing this and gave everything a good look over- nothing seems to stand out)
Dave Wilson
'77 Eleganza II
Photos @ http://www.gmcmhphotos.com/photos/member.php?uid=2183&protype=1
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| Re: A "Short" Question [message #93707 is a reply to message #93700] |
Wed, 28 July 2010 19:38 |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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Have you ever been behind an old car with one dim tail lite and one bright one??? When they step on the brake it goes out! No Ground!! Current flows through the tail filament, through the brake fillament to the oposite side brake fillament and then to the good ground. When voltage is applied to the brake filament current won't flow through ether, because of no or poor ground. Check all your grounds. Remove, clean, wire brush and replace. Tighten. Not only can it not hurt, might prevent problems later. Good luck,,,PL
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| Re: [GMCnet] A "Short" Question [message #93753 is a reply to message #93708] |
Thu, 29 July 2010 01:04 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| Mr ERFisher wrote on Wed, 28 July 2010 19:46 |
>
> Have you ever been behind an old car with one dim tail lite and one bright
> one??? When they step on the brake it goes out! No Ground!!
that is my guess also,
there are 2 grounds to the dash, and neither one are any good.
Run one from the dash to the engine (mother earth ground)
read here
http://www.gmcmotorhome.info/chassis.html#GROUND
sent by iGene
Gene Fisher -- 74-23,77PB/ore/ca
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I have two guesses:
One is the above mentioned ground. The factory ground runs from the IP out the front to the aluminum plate that has the boost solenoid mounted on it. From the plate there is a second wire that runs to the negative engine battery terminal. The wire is usually loose at the IP itself.
My second guess is a melted nichrome wire. This is wire that Gene protects with his APC. If you do not have the APC, or Jim Bound's alternator resistor mod, I would investigate the melted nichrome wire problem.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: A "Short" Question [message #93803 is a reply to message #93700] |
Thu, 29 July 2010 10:59 |
Dave Wilson
Messages: 94
Registered: September 2009
Location: Livonia, MI
Karma: 0
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Thank you all for the helpful suggestions. I plan on grounding this weekend (why did my kids just run away from me?) 
Dave Wilson
'77 Eleganza II
Photos @ http://www.gmcmhphotos.com/photos/member.php?uid=2183&protype=1
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