Whats this wire for? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Gene · 02-08-2011, 06:30 PM

I'm replacing my underhood wiring with a new wiring harness and don't recall where or what this brown wire plugs into? It's not the brake pressure plug, it's on the other side running out of the wires and has a different plug?

1low · 02-08-2011, 06:44 PM

Not sure what it does but it pluge in to a wire that comes out of a gromet with 4 other wires that go uneder the dash i would like to know what it is for also

**slomotion** · 02-08-2011, 07:34 PM

If it's run the other way, will it reach the heater fan motor? (Just a SWAG)

Gene · 02-08-2011, 07:44 PM

Quote:

Originally Posted by slomotion

If it's run the other way, will it reach the heater fan motor? (Just a SWAG)

No, that one is part of the a/c /heater harness. I looked at my old wiring harness and it doesnt have this plug?

**leddzepp** · 02-08-2011, 07:37 PM

I was wondering what that wire is for too. power goes to it when the ignition is on...

BadaSs_Cal · 02-08-2011, 07:46 PM

that wire isnt even on mine.. ran out and check.

68custom396 · 02-08-2011, 07:49 PM

It's for the brake light warning that comes on in the cluster. It plugs in by the master cylinder on the porportioning valve. If it's like mine then it's a little to short and I had to add some wire
Posted via Mobile Device

**leddzepp** · 02-08-2011, 07:59 PM

Quote:

Originally Posted by 68custom396

It's for the brake light warning that comes on in the cluster. It plugs in by the master cylinder on the porportioning valve. If it's like mine then it's a little to short and I had to add some wire
Posted via Mobile Device

nope, that is a different wire

Gene · 02-08-2011, 08:00 PM

Quote:

Originally Posted by 68custom396

It's for the brake light warning that comes on in the cluster. It plugs in by the master cylinder on the porportioning valve. If it's like mine then it's a little to short and I had to add some wire
Posted via Mobile Device

Nope, I have a plug for that one and it reaches the proportioning valve just fine. Still a mystery???

Luvlegs · 02-08-2011, 07:57 PM

It's not part of the 72? anti transmission knock down shift carb fouly thingee by any chance? (there's something in that area on 72s I think that gets "eliminated" by everyone.

Roadmarks · 02-08-2011, 07:57 PM

68custom396, I disagree. That wire that you describe has a round rubber shield around it. I think the one in the picture is for the "Transmission Spark control" that some of the trucks had. Some of the other holes in the picture may be concerned also.

**leddzepp** · 02-08-2011, 08:01 PM

Quote:

Originally Posted by Roadmarks

68custom396, I disagree. That wire that you describe has a round rubber shield around it. I think the one in the picture is for the "Transmission Spark control" that some of the trucks had. Some of the other holes in the picture may be concerned also.

I think we have a winner...

sjarrett71 · 02-08-2011, 08:07 PM

I've got the same wire and it's not attached to anything. I have a 72 GMC.

68custom396 · 02-08-2011, 08:08 PM

That's right I do recall tucking that wire back into my rail now that I think about it. Thanks to all for being so quick to correct me lol
Posted via Mobile Device

DaSchlange · 02-08-2011, 08:22 PM

I went out and snapped this on my droid real quick. I think a lot of people disconnect this wire because it malfunctions and causes a light to stay on all of the time. Someone can clarify for me here? I can ask my dad when I get a chance, he's the one who disconnected it for that reason. This is on a 1972 Custom 10 3 speed on the tree 250 6 cylinder motor.

sjarrett71 · 02-08-2011, 08:40 PM

Quote:

Originally Posted by DaSchlange

I went out and snapped this on my droid real quick. I think a lot of people disconnect this wire because it malfunctions and causes a light to stay on all of the time. Someone can clarify for me here? I can ask my dad when I get a chance, he's the one who disconnected it for that reason. This is on a 1972 Custom 10 3 speed on the tree 250 6 cylinder motor.

I've got the factory wire you pictured connected to my proportioning valve and I have the wire the OP posted. They are 2 seperate wires.

**leddzepp** · 02-08-2011, 08:45 PM

Quote:

Originally Posted by sjarrett71

I've got the factory wire you pictured connected to my proportioning valve and I have the wire the OP posted. They are 2 seperate wires.

x 2.

68custom396 · 02-08-2011, 08:24 PM

I have a new powerbooster/master cylinder from CPP and the porportioning valve is mounted a lil different than stock plus the connector is different. Just incase anybodys was wondering why I added wire
Posted via Mobile Device

Longhorn Man · 02-08-2011, 08:27 PM

the spark control thing is a seperate add onharness (started in 69 or 70)... that's not part of it.

Gene · 02-08-2011, 08:47 PM

I know for a fact that it is not the wire that goes to the brakes. Here is a pic of both wires and plugs side by side.

Willys47 · 02-08-2011, 08:58 PM

would that wire be for a tranny kick down power for a turbo 400?

**leddzepp** · 02-08-2011, 09:04 PM

Quote:

Originally Posted by Willys47

would that wire be for a tranny kick down power for a turbo 400?

Nope. I have that too, it is separate.

vectorit · 02-08-2011, 09:17 PM

Under hood light?

I seem to remember there was a little lamp that attached to the fender, and you would twist it apart from the mount on the fender. Then it had a long cord with a light at the end, and you could use it to look around the engine compartment.

I actually have one of these, though it is not set up on my burb. It's probably in one of my bins of spare parts buried.

What about cruise control?

Just pulling guesses out my...

Bruce88 · 02-08-2011, 09:58 PM

I think its for the TCS circuit

Name: TCS-Circuit.jpg
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**leddzepp** · 02-09-2011, 02:31 AM

Quote:

Originally Posted by vectorit

Under hood light?

This was one of my guesses as well. I pulled my truck apart, put it all back together...and have this same wire that is "left over". I don't remember it attaching to anything prior to disassembly...it may have been tucked into the harness. It is not for the brakes. The trans kick down switch is on the gas pedal and the harness it attaches to is separate and goes directly to the TH400. My truck runs fine, no electrical problems, so it doesn't go to anything "important" as far as I can tell. 12 volts flow through it when the ignition is on, so it is a keyed source. The wire is very thin gauge, so I suspect it doesn't power anything that requires high amperage. It is solid brown also, but the TCS diagram makes sense to me. Where is the TCS located? I am currently using this wire for the electric choke on my Edelbrock...it plugged right in

02-08-2011, 06:30 PM	#1
Gene Registered User Join Date: Aug 2002 Location: Muskogee, Oklahoma Posts: 2,914	Whats this wire for? I'm replacing my underhood wiring with a new wiring harness and don't recall where or what this brown wire plugs into? It's not the brake pressure plug, it's on the other side running out of the wires and has a different plug? Last edited by Gene; 02-08-2011 at 06:31 PM.

02-08-2011, 06:44 PM	#2
1low Registered User Join Date: Feb 2010 Location: Moyie Springs ID. Posts: 160	Re: Whats this wire for? Not sure what it does but it pluge in to a wire that comes out of a gromet with 4 other wires that go uneder the dash i would like to know what it is for also

02-08-2011, 07:34 PM	#3
slomotion Old Duffer Join Date: Mar 2003 Location: Maine Posts: 1,821	Re: Whats this wire for? If it's run the other way, will it reach the heater fan motor? (Just a SWAG) __________________ '68 Short C20 Flatbed Dually w/ 292 4bbl, Langdon cast headers, and WC T5 trans. '81 G10 Shorty Van "Good judgement comes from experience, and a lot of that comes from bad judgement." Will Rogers "Under promise, then over achieve."

02-08-2011, 07:37 PM	#5
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 20,005	Re: Whats this wire for? I was wondering what that wire is for too. power goes to it when the ignition is on... __________________ 1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man

02-08-2011, 07:46 PM	#6
BadaSs_Cal Registered User Join Date: Feb 2010 Location: Walnut Grove, Ca Posts: 216	Re: Whats this wire for? that wire isnt even on mine.. ran out and check. __________________ 66 Gmc 1 ton. Long Step 351e V6 69 1/2 CHEVROLET (now a shortbed) LONGBED!:devil 61 Shortbed Fleetside 1/2 ton.. in progress Next a 50-53! MY BUILD THREAD http://67-72chevytrucks.com/vboard/s...d.php?t=447926

02-08-2011, 07:49 PM	#7
68custom396 Registered User Join Date: Nov 2009 Location: Lubbock Tx Posts: 21	Re: Whats this wire for? It's for the brake light warning that comes on in the cluster. It plugs in by the master cylinder on the porportioning valve. If it's like mine then it's a little to short and I had to add some wire Posted via Mobile Device

02-08-2011, 07:57 PM	#10
Luvlegs Registered User Join Date: Sep 2005 Location: Smith Mountain Lake Virginia Posts: 1,537	Re: Whats this wire for? It's not part of the 72? anti transmission knock down shift carb fouly thingee by any chance? (there's something in that area on 72s I think that gets "eliminated" by everyone. __________________ "A cat will almost always blink when hit between the eyes with a ball peen hammer" (you don't always have to state the obvious) Wear your PPE! You can eat with false teeth but you can't see with a false eye. 1959 Studebaker Silverhawk 350/400 1972 C10 L6 3OTT 2005 F350 - Built - whew!

02-08-2011, 07:57 PM	#11
Roadmarks Registered User Join Date: Apr 2010 Location: Raleigh NC Posts: 157	Re: Whats this wire for? 68custom396, I disagree. That wire that you describe has a round rubber shield around it. I think the one in the picture is for the "Transmission Spark control" that some of the trucks had. Some of the other holes in the picture may be concerned also.

02-08-2011, 08:07 PM	#13
sjarrett71 Registered User Join Date: Dec 2006 Location: Rolla, MO Posts: 2,463	Re: Whats this wire for? I've got the same wire and it's not attached to anything. I have a 72 GMC. __________________ -Scott-

02-08-2011, 08:08 PM	#14
68custom396 Registered User Join Date: Nov 2009 Location: Lubbock Tx Posts: 21	Re: Whats this wire for? That's right I do recall tucking that wire back into my rail now that I think about it. Thanks to all for being so quick to correct me lol Posted via Mobile Device

02-08-2011, 08:22 PM	#15
DaSchlange Registered User Join Date: Sep 2010 Location: Gainesville, MO Posts: 251	Re: Whats this wire for? I went out and snapped this on my droid real quick. I think a lot of people disconnect this wire because it malfunctions and causes a light to stay on all of the time. Someone can clarify for me here? I can ask my dad when I get a chance, he's the one who disconnected it for that reason. This is on a 1972 Custom 10 3 speed on the tree 250 6 cylinder motor.

02-08-2011, 08:24 PM	#18
68custom396 Registered User Join Date: Nov 2009 Location: Lubbock Tx Posts: 21	Re: Whats this wire for? I have a new powerbooster/master cylinder from CPP and the porportioning valve is mounted a lil different than stock plus the connector is different. Just incase anybodys was wondering why I added wire Posted via Mobile Device

02-08-2011, 08:27 PM	#19
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: Whats this wire for? the spark control thing is a seperate add onharness (started in 69 or 70)... that's not part of it.

02-08-2011, 08:47 PM	#20
Gene Registered User Join Date: Aug 2002 Location: Muskogee, Oklahoma Posts: 2,914	Re: Whats this wire for? I know for a fact that it is not the wire that goes to the brakes. Here is a pic of both wires and plugs side by side.

02-08-2011, 08:58 PM	#21
Willys47 Registered User Join Date: Dec 2007 Location: Nanaimo B.C. Posts: 604	Re: Whats this wire for? would that wire be for a tranny kick down power for a turbo 400? __________________ I was hooked on these trucks since 1982 when I drove my budys fathers 1968 Custum GMC 396 automatic dana 60 rear with a power lock diff what a ride more fun then we will we can ever tell!!



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02-08-2011, 09:17 PM	#23
vectorit What? Join Date: Jun 2007 Location: Southern California Posts: 7,617	Re: Whats this wire for? Under hood light? I seem to remember there was a little lamp that attached to the fender, and you would twist it apart from the mount on the fender. Then it had a long cord with a light at the end, and you could use it to look around the engine compartment. I actually have one of these, though it is not set up on my burb. It's probably in one of my bins of spare parts buried. What about cruise control? Just pulling guesses out my... __________________ Chris 1968 K20 Suburban 1972 K10 LWB PU Last edited by vectorit; 02-08-2011 at 09:18 PM.

02-08-2011, 09:58 PM	#24
Bruce88 Registered User Join Date: Oct 2008 Location: Everett, WA Posts: 326	Re: Whats this wire for? I think its for the TCS circuit __________________ My Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=318544

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