Mystery wire under my hood - The 1947 - Present Chevrolet & GMC Truck Message Board Network

71Shortbed · 10-14-2005, 07:33 PM

Anybody know where this wire should go? It's a tan wire coming out of the harness in the firewall gutter. It has a 90 degree plugin connector with a 12 inch pigtail pulled into it. The other end of the pigtail is broken off and it's just hanging loose.

OhioDan · 10-14-2005, 07:37 PM

Looks like it goes to the plug on the proportioning valve?

Sweet72 · 10-14-2005, 07:42 PM

Ohio is right but I think your proportioning valve is a replacement and doesn't appear to have the brake warning switch.

72BLAZERDUDE · 10-14-2005, 07:54 PM

71Shortbed · 10-14-2005, 07:58 PM

Thanks guys. That explains why my warning light never comes on.

**uncle** · 10-14-2005, 08:04 PM

Looks like a drum brake P valve to me.

71Shortbed · 10-14-2005, 09:44 PM

I checked it and there is a rubber wire connecter on the bottom of the valve. You can see part of it in the picture. I guess I'll hook the sucker up.

Longhorn Man · 10-14-2005, 10:40 PM

I was going to recomend looking there for it...
How can one tell if it is a drum distrabution valve, or a disc/drum proportioning valve?

**pjmoreland** · 10-14-2005, 11:10 PM

It looks like the drum/drum proportioning valve that was on my '67. My '72 has a disk/drum proportioning valve that is way bigger than that and has a little rubber cap in the front of it. Also the front brake line attaches to the bottom of the proportioning valve instead of the front.

Longhorn Man · 10-15-2005, 06:13 AM

well hot dam... I didn't know they looked so different. cool.

krue · 10-15-2005, 07:11 AM

Learn something new everyday.

OhioDan · 10-15-2005, 10:21 AM

I was going to say that the prop. valve in the pic looked like the one I had on mine (all drum) before I changed it to drum/disk. Well Andy, at least ya learned something today? So it's not entirely wasted?

Longhorn Man · 10-16-2005, 10:54 AM

Yeah, but I was trying soooo hard NOT to learn anything today!

10-14-2005, 07:33 PM	#1
71Shortbed Registered User Join Date: Jul 2004 Location: Lilburn, GA Posts: 209	Mystery wire under my hood Anybody know where this wire should go? It's a tan wire coming out of the harness in the firewall gutter. It has a 90 degree plugin connector with a 12 inch pigtail pulled into it. The other end of the pigtail is broken off and it's just hanging loose. Attached Images Last edited by 71Shortbed; 10-14-2005 at 07:34 PM.

10-14-2005, 07:37 PM	#2
OhioDan Registered User Join Date: Apr 2002 Location: New Carlisle, Ohio,USA Posts: 1,404	Looks like it goes to the plug on the proportioning valve? __________________ LIFE AIN'T EASY WHEN YER FAT AND GREASY! GMC= Got More Class! 1970 GMC LWB, Fleetside, 350/4spd, Flowmaster "40's", 2002 GMC 16" Rallies, cowl hood,and added a bunch of options that weren't there when I started.

10-14-2005, 07:42 PM	#3
Sweet72 Registered User Join Date: Nov 2003 Location: Alexandria, VA Posts: 1,534	Ohio is right but I think your proportioning valve is a replacement and doesn't appear to have the brake warning switch. __________________ '72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction.

10-14-2005, 07:54 PM	#4
72BLAZERDUDE Registered User Join Date: Jan 2002 Location: WATAUGA,TX Posts: 660	__________________ 72 2wd 307/AT/AC/TILT WHEEL 78 JIMMY HIGH SIERRA

10-14-2005, 08:04 PM	#6
uncle Senior Member Join Date: Aug 2003 Location: Conyers,Ga. Posts: 7,286	P Valve Looks like a drum brake P valve to me.

10-14-2005, 07:58 PM	#5
71Shortbed Registered User Join Date: Jul 2004 Location: Lilburn, GA Posts: 209	Thanks guys. That explains why my warning light never comes on.

10-14-2005, 09:44 PM	#7
71Shortbed Registered User Join Date: Jul 2004 Location: Lilburn, GA Posts: 209	I checked it and there is a rubber wire connecter on the bottom of the valve. You can see part of it in the picture. I guess I'll hook the sucker up. Attached Images Last edited by 71Shortbed; 10-14-2005 at 09:47 PM.

10-14-2005, 10:40 PM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	I was going to recomend looking there for it... How can one tell if it is a drum distrabution valve, or a disc/drum proportioning valve?

10-14-2005, 11:10 PM	#9
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,426	It looks like the drum/drum proportioning valve that was on my '67. My '72 has a disk/drum proportioning valve that is way bigger than that and has a little rubber cap in the front of it. Also the front brake line attaches to the bottom of the proportioning valve instead of the front.

10-15-2005, 06:13 AM	#10
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	well hot dam... I didn't know they looked so different. cool.

10-15-2005, 07:11 AM	#11
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Learn something new everyday. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

10-15-2005, 10:21 AM	#12
OhioDan Registered User Join Date: Apr 2002 Location: New Carlisle, Ohio,USA Posts: 1,404	I was going to say that the prop. valve in the pic looked like the one I had on mine (all drum) before I changed it to drum/disk. Well Andy, at least ya learned something today? So it's not entirely wasted? __________________ LIFE AIN'T EASY WHEN YER FAT AND GREASY! GMC= Got More Class! 1970 GMC LWB, Fleetside, 350/4spd, Flowmaster "40's", 2002 GMC 16" Rallies, cowl hood,and added a bunch of options that weren't there when I started. Last edited by OhioDan; 10-15-2005 at 10:22 AM.

10-16-2005, 10:54 AM	#13
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: Mystery wire under my hood Yeah, but I was trying soooo hard NOT to learn anything today!



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.