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C3 Electrical

Dimmer switch? (1/6)
 5/29/15 8:23am
bcliffGold Member
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TOPTON, PA - USA

Vette(s):
71 454 convertible, mulsanne blue,a/c, matching numbers, 48K miles


Joined: 5/5/2002
Posts: 313

HI Guys,
Quick question, I was driving my 71 last night and all of a sudden my lights that are controlled by the dimmer switch went out. When I turn on all the way the interior lights work, headlights work but nothing for speedo, tach, guages etc. I haven't had a chance to troubleshoot but thought I would see what your suggestions are. Not looking forward to taking the dash apart AGAIN!

Thanks,
Tom



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Tom
71 454/365 Mulsanne Blue Convertible


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Re: Dimmer switch? (2/6)
 5/29/15 10:20am
F4Gary
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Grapevine, TX - USA

Vette(s):
1972 LT-1 convertible with factory air.


Joined: 8/26/2006
Posts: 961

Fuse?

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Re: Dimmer switch? (3/6)
 5/29/15 12:10pm
bcliffGold Member
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TOPTON, PA - USA

Vette(s):
71 454 convertible, mulsanne blue,a/c, matching numbers, 48K miles


Joined: 5/5/2002
Posts: 313

At first I thought fuse, but the tach/speedometer and center console fuses are not on the same fuse.

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Tom
71 454/365 Mulsanne Blue Convertible


Re: Dimmer switch? (4/6)
 5/29/15 12:19pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
Posts: 19601

So....you're talking about the dash light dimmer on the headlight switch, right?
IF they all went out at the same time, I'd suspect either a problem with the connector on the headlight switch, or the switch itself. Unhappy


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Joel Adams
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Re: Dimmer switch? (5/6)
 5/29/15 2:55pm
kstyerLifetime Member
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CUYAHOGA FALLS, OH - USA

Vette(s):
1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!


Joined: 12/2/2003
Posts: 6411

The interior lights and others controlled by turn the headlight dimmer all of the way is connected to a switch in the headlight switch.  There are several different and separate switches in the headlight switch.
The dash light dimmer operated by rotating the headlight switch, but not all the way to activate interior lights, is a variable resistor.  That power comes from the parking light circuit, but not the headlight circuit.  So the park or running lights must be on first.  Power comes from that circuit to a usually 5 amp fuse and returns to the headlight switch resistor to feed the variable dash lights.
The park/running lights work so the power feed is good.  Check the separate 5 amp fuse (maybe 4, maybe 7.5) If that is good, back to the resistor.  If the power to the lights is good but the problem still exists, be sure to check the ground wire attached to the gauges/speedo/tach units.  They all run together into one ground point.  If it becomes weak it will affect all of those lights.
The dash light wire is light grey,  the ground is black. 
Re: Dimmer switch? (6/6)
 5/29/15 5:09pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
Posts: 19601

Shocked Hey stranger!!! Good to see ya back on the forums!! Hug

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Joel Adams
C3VR Lifetime Member #56    

My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"