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Topic: Whats the brown wire for

in Forum: C3 Electrical

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Whats the brown wire for (1/9)
11/12/07 8:31pm

lukesvette

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HOWELL, NJ - USA

Vette(s):
1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.

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that runs from the AC seceltor switch to the ignition switch? Wits%20End

Is that the wire that starts a spinnin my blower motor every time I puts the key in the run position?? Geek

Thanks Team!

Paul

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Whats the brown wire for (2/9)
11/12/07 9:00pm

Adams' Apple

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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

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The brown wire comes from the fuse box...or at least, it's supposed to! Sounds like "Bubba" done been there...

The fan switch should have two orange wires, one goes to the blower motor, the other to the heater resister, mounted in the A/C plenum, under the hood.
The brown wire is power from the fuse box.
The blue, and yellow wires also go to the heater resistor...this is what gives you the low, med, and med/high blower speeds.
Does the brown wire look like it ain't supposed to be on the ign. switch connector, as in, someone spliced it in?

I see NO brown wires coming from, or going to the ign. switch...

What speed does the fan run when you turn the key on? If it is slow/low, your fan switch may have problems. The fan on A/C cars should be OFF if the switch is in the off position. I think the blower does run on low on the non-A/C cars, regardless of the switch position. Adams' Apple2007-11-12 22:04:45

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Whats the brown wire for (3/9)
11/13/07 2:54am

tuxblacray

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Greensburg, IN - USA

Vette(s):
Previous: 1984 Silver / Charcoal Coupe, 1988 Maroon Coupe / 1989 Artic White Coupe / 2001 Speedway White Roadster / Present:1976 Stingray Black / Black, Auto, 350 slightly modified (355 hp) Luxor Wires Redline Tires. / 1989 Roadster Bright Red...

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What in world is that..... sorry Paul I couldn't resist!

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Whats the brown wire for (4/9)
11/13/07 7:17am

lukesvette

Joel,

According to the wiring diagram, there are 2 spliced brown wires on the factory connector (just as it is on the actual harness). One runs to the blower relay on the firewall, and the other runs to a fuse, however, it shows an orange wire on the other side of that fuse going to ignition. The blower runs at low speed any time the ignition is in the run position.

This may just be me learning how to read wiring diagrams in detail. So does the orange wire generally power up any ignition driven accessory at the fuse block or is it exclusive to the brown wire on the diagram. Looks that way to me.

Tux, have no fear - there is no AC in the car for now. promise you a ride on a nice hot day!!!!

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Whats the brown wire for (5/9)
11/13/07 10:03am

Adams' Apple

I don't have the diagrams here, but it sounds like we have different diagrams. If you have the factory service manual diagram, then it is prolly more correct. The one I looked at last nite only showed one brn wire. I'll check again when I gits home this eve.

The only blower relay I'm aware of is the high speed relay, which only comes into play when "high" is selected.
If your car was originally built with A/C, the fan switch should have 4 positions, one of them being "Off". Your fan switch may be bad, causing the continuous operation of the blower at low speed. There are other possibilities, but that would be the most common.

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Whats the brown wire for (6/9)
11/14/07 5:35am

6880Mike
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Horse Cave, KY - USA

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1968 convertible; 1980 L-82

Joined: 10/22/2007
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[QUOTE=Adams' Apple]...I think the blower does run on low on the non-A/C cars, regardless of the switch position.... [/QUOTE]

Correct. On some years, the blower fan automatically comes on at low speed when the vehicle is started. GM felt this would aid cabin ventilation. Might occur with the AC cars, too.

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Whats the brown wire for (7/9)
11/17/07 12:27pm

2 cruzn

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Poquoson, VA - USA

Vette(s):
73 Conv, Blue-Green/White Top - 454, M21 - Dark Saddle Leather, Power Windows, A/C, Tilt/Tele, AM/FM St. (orig. and sounds like it too).#2 -- 2007 Coupe,3 LT package, Z51 option, Victory Red, Ebony Int. Clear Top.

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Mystery brown wire! (8/9)
3/16/24 11:49am

dblackwell
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1974 coupe

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I am rebuilding dash wiring harness on my 74 Vette. The ignition switch had one brown wire and one hanging lose. I think it goes to heater resistor.

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Re: Whats the brown wire for (9/9)
3/20/24 5:16pm

Steevo
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San Diego, CA - USA

Vette(s):
'73 L48 Coupe, 383, M20, A/C, Electric Windows. Matterhorn White Jet-Glo w/ Dark Blue interior. Rochester, Edelbrock, Blackjack Ceramics, Borlas w/ 2.5" mandrel X over, Cooper Cobras on both OEM Steel and Aluminum Wheels.

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For what it's worth, on my '73 L-48, a brown wire powers the Dukes of Hazard Hood Intake flap panel when you floor it (guess they figured the 190HP 350 needed ALL the help it could get back then 😄).

So, the brown wire seems to be a 12vdc supplier (not necessarily Common) to a number of circuits.

It wasn't exactly a Burn Job, but I rewired the Main Harness on this car, finding wires with melted insulation throughout. Was fun though; far easier than that of an A-6. 😉

Steve

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