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

72gmcshorty · 05-15-2003, 03:57 PM

On my wiring harness, at the firewall junction, on the top row. One Red , one black, one black with white stripe. I know what the red and the black with white stripe are for but what about black? It's not in my wiring diagram. Its a 72 harness.

AND after doing the removal of external regulator, I should get a complete circuit from the tan wire in the harness to the white wire going to the alternator, correct? (when using a tester)

1969 GMC · 05-15-2003, 03:58 PM

isn't black usually ground?

72gmcshorty · 05-15-2003, 05:24 PM

In the wiring diagrams the ground wires for the headlight harness splice into a dark blue on one side and go straight to ground on the other side. This black wire begins right at the firewall connector and i have no idea what it connects to or where it goes.

72gmcshorty · 05-16-2003, 02:41 AM

Anyone help? My manual doesn't show 72 wiring diagram.

72 CustomCamper · 05-16-2003, 02:49 AM

Hey 72gmcshorty the black wire goes to the junction block on the pass side finder and connects with the pos side of the battery.
http://www.geocities.com/chevroletc1070/v8engcomp.html ...

Chuck

73stepside · 05-16-2003, 03:39 AM

black with whit stripe is for the ammeter guage it should have a fuse in it at the radiator support on either corner. that's how i chased it in the 70 chassis service manual

72gmcshorty · 05-16-2003, 12:38 PM

Thanks for the link. Any idea what size fuse is needed and what this wire is for?

71Chev · 05-16-2003, 12:55 PM

4 amp

72gmcshorty · 05-16-2003, 01:00 PM

I mean the pure black wire. Not the one for the gauge

71Chev · 05-16-2003, 01:13 PM

Both wires for the amp gauge take 4 amp fuses.

72gmcshorty · 05-16-2003, 01:20 PM

There's 2 wires for the gauge? Now you have me confused. I know the black wire with white stripe has two inline fuses at 4 amps each. I'm sure this wire is for the gauge. I need to know about the solid black wire that is located right next to the black/white stripe wire on the firewall junction of the harness. In the diagram from the link above it shows the Black wire and the B/W wire as both having inline fuses. What size fuse is in the other wire? Look at the picture and you'll see what I mean.

71Chev · 05-16-2003, 02:51 PM

The black wire that goes to the junction block takes a 4 amp.
the black w/ white stripe and the black going to the junction block are both for the amp gauge.

05-15-2003, 03:57 PM	#1
72gmcshorty Registered User Join Date: Jul 2001 Location: North Delta, British Columbia Posts: 1,344	Whats this wire for? On my wiring harness, at the firewall junction, on the top row. One Red , one black, one black with white stripe. I know what the red and the black with white stripe are for but what about black? It's not in my wiring diagram. Its a 72 harness. AND after doing the removal of external regulator, I should get a complete circuit from the tan wire in the harness to the white wire going to the alternator, correct? (when using a tester) __________________ 1992 Gmc 2wd 1972 Chevy Blazer 2wd

05-15-2003, 03:58 PM	#2
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	isn't black usually ground? __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

05-15-2003, 05:24 PM	#3
72gmcshorty Registered User Join Date: Jul 2001 Location: North Delta, British Columbia Posts: 1,344	In the wiring diagrams the ground wires for the headlight harness splice into a dark blue on one side and go straight to ground on the other side. This black wire begins right at the firewall connector and i have no idea what it connects to or where it goes. __________________ 1992 Gmc 2wd 1972 Chevy Blazer 2wd

05-16-2003, 02:41 AM	#4
72gmcshorty Registered User Join Date: Jul 2001 Location: North Delta, British Columbia Posts: 1,344	Anyone help? My manual doesn't show 72 wiring diagram. __________________ 1992 Gmc 2wd 1972 Chevy Blazer 2wd

05-16-2003, 02:49 AM	#5
72 CustomCamper huh ??? Join Date: Nov 2002 Location: Fredericksburg,Va. Posts: 3,369	Hey 72gmcshorty the black wire goes to the junction block on the pass side finder and connects with the pos side of the battery. http://www.geocities.com/chevroletc1070/v8engcomp.html ... Chuck __________________ 90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!"

05-16-2003, 03:39 AM	#6
73stepside Registered User Join Date: Feb 2002 Location: Moore OK 73160 Posts: 974	black with whit stripe is for the ammeter guage it should have a fuse in it at the radiator support on either corner. that's how i chased it in the 70 chassis service manual __________________ 04 GMC Sierra RCSS 70 CST LWB 04 HD Sportster 1200 Custom

05-16-2003, 12:38 PM	#7
72gmcshorty Registered User Join Date: Jul 2001 Location: North Delta, British Columbia Posts: 1,344	Thanks for the link. Any idea what size fuse is needed and what this wire is for? __________________ 1992 Gmc 2wd 1972 Chevy Blazer 2wd Last edited by 72gmcshorty; 05-16-2003 at 12:46 PM.

05-16-2003, 12:55 PM	#8
71Chev Senior Member Join Date: Dec 2000 Location: Indiana Posts: 3,074	4 amp __________________ 71 Chevy CST Long Fleet 350/350/3.07 leaf rear.

05-16-2003, 01:00 PM	#9
72gmcshorty Registered User Join Date: Jul 2001 Location: North Delta, British Columbia Posts: 1,344	I mean the pure black wire. Not the one for the gauge __________________ 1992 Gmc 2wd 1972 Chevy Blazer 2wd

05-16-2003, 01:13 PM	#10
71Chev Senior Member Join Date: Dec 2000 Location: Indiana Posts: 3,074	Both wires for the amp gauge take 4 amp fuses. __________________ 71 Chevy CST Long Fleet 350/350/3.07 leaf rear.

05-16-2003, 01:20 PM	#11
72gmcshorty Registered User Join Date: Jul 2001 Location: North Delta, British Columbia Posts: 1,344	There's 2 wires for the gauge? Now you have me confused. I know the black wire with white stripe has two inline fuses at 4 amps each. I'm sure this wire is for the gauge. I need to know about the solid black wire that is located right next to the black/white stripe wire on the firewall junction of the harness. In the diagram from the link above it shows the Black wire and the B/W wire as both having inline fuses. What size fuse is in the other wire? Look at the picture and you'll see what I mean. __________________ 1992 Gmc 2wd 1972 Chevy Blazer 2wd

05-16-2003, 02:51 PM	#12
71Chev Senior Member Join Date: Dec 2000 Location: Indiana Posts: 3,074	The black wire that goes to the junction block takes a 4 amp. the black w/ white stripe and the black going to the junction block are both for the amp gauge. __________________ 71 Chevy CST Long Fleet 350/350/3.07 leaf rear.

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