The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Where does the negative battery cable wire go?

**71CHEVYSHORTBED402** · 03-09-2023, 05:59 PM

For what worth seems I've finally wrapped my head around the junction block. The wires are in the "forward lamps harness", includes alternator. Works like this, corrections and that welcome.

The junction block serves to operate the battery gauge, and the connection powers the vehicle as well. The block’s stud terminal takes three wire terminals using a 3/8” hex serrated flange nut with #10-24 threads. The three wires are described as:

• One 12 AWG red wire with a fusible link. Reference “Red, 12 AWG with fuses” for further description.
• One 18 AWG black wire with a 4 AMP inline fuse, for the battery side of the battery gauge.
• One 12 AWG red wire from the positive battery terminal.
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Black & White, 18 AWG: The circuit runs from #1 on the instrument panel connector to the fuse box. The wire has a 4 AMP inline fuse near the LH headlight. This wire is for the alternator side of the battery gauge.
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Red, 12 AWG with fuses:

The red wire’s 14 AWG fusible link is near the LH headlight before it’s soldered with the black and white wire mentioned above and three additional red wires for factory alternators.
• One red wire connects to the alternator.
• One red wire connects to the junction block with a 14 AWG fusible link.
• One red wire connects to the voltage regulator.

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The black wire with an in-line fuse is for the battery side of the battery gauge. The circuit's wire is black and brown inside the cab.

The black & white wire (alternator side battery gauge) and black & brown wire (battery side battery gauge) run to the gauge cluster.

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Big props to Vette's write-ups on the subject, it just took a while to finally click. He explains it's necessary to separate the two currents for the battery gauge. It's easy to see why the wires connected to the junction block, battery and alternator have inline fuse and links before they run into the cab.

03-09-2023, 05:59 PM	#27
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,129	Re: Where does the negative battery cable wire go? For what worth seems I've finally wrapped my head around the junction block. The wires are in the "forward lamps harness", includes alternator. Works like this, corrections and that welcome. The junction block serves to operate the battery gauge, and the connection powers the vehicle as well. The block’s stud terminal takes three wire terminals using a 3/8” hex serrated flange nut with #10-24 threads. The three wires are described as: • One 12 AWG red wire with a fusible link. Reference “Red, 12 AWG with fuses” for further description. • One 18 AWG black wire with a 4 AMP inline fuse, for the battery side of the battery gauge. • One 12 AWG red wire from the positive battery terminal. ______________________________________________________ Black & White, 18 AWG: The circuit runs from #1 on the instrument panel connector to the fuse box. The wire has a 4 AMP inline fuse near the LH headlight. This wire is for the alternator side of the battery gauge. _____________________________________________________________________ Red, 12 AWG with fuses: The red wire’s 14 AWG fusible link is near the LH headlight before it’s soldered with the black and white wire mentioned above and three additional red wires for factory alternators. • One red wire connects to the alternator. • One red wire connects to the junction block with a 14 AWG fusible link. • One red wire connects to the voltage regulator. ___________________________________________ The black wire with an in-line fuse is for the battery side of the battery gauge. The circuit's wire is black and brown inside the cab. The black & white wire (alternator side battery gauge) and black & brown wire (battery side battery gauge) run to the gauge cluster. ______________________________________________ Big props to Vette's write-ups on the subject, it just took a while to finally click. He explains it's necessary to separate the two currents for the battery gauge. It's easy to see why the wires connected to the junction block, battery and alternator have inline fuse and links before they run into the cab. __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s details such as OEM identifications& part numbers, written in short order. 700+ images include assm, illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 03-09-2023 at 06:13 PM.