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Old 10-18-2022, 03:53 PM   #1
71CHEVYSHORTBED402
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Negative Battery Cable wire and Junction Block

Edited title.....

I never had the wire off the negative battery terminal, perhaps because it was a factory top post battery. I'm installing a side post battery.

I'm wondering where the negative cable's wire is supposed to be attached. Seems the fender is right, but? If the fender, my 72 is placed here, does that look right to you? Thanks
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Old 10-18-2022, 04:54 PM   #2
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Re: Where does the negative battery cable wire go?

I have side post on my 72, this is where my - aux wire attaches. Basically anywhere on fender it can reach. Typically a star washer is also used

The relays are for my headlights
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Old 10-18-2022, 05:40 PM   #3
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Re: Where does the negative battery cable wire go?

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I have side post on my 72, this is where my - aux wire attaches. Basically anywhere on fender it can reach. Typically a star washer is also used

The relays are for my headlights
Thank you. I was wondering about a star washer or such, makes sense.


Another question please, anyone, perhaps a dumb one. Everything is new, I've yet to test with a battery. If I connect the positive cable to the mini starter I installed, but don't connect the purple wire to the starter solenoid (S terminal), does that mean I have auxiliary power without risking engine start?
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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 of OEM identifications and part numbers, all 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
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Old 10-18-2022, 05:56 PM   #4
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Re: Where does the negative battery cable wire go?

I would assume you do if you don't turn key "past" ACC mode.

You have a points dizzy or a HEI type?

leaving key on points dizzy is a problem

I assume you have the AUX + battery cable (smaller one) going to the buss terminal near RF fender
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Old 10-18-2022, 06:23 PM   #5
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Re: Where does the negative battery cable wire go?

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I would assume you do if you don't turn key "past" ACC mode.

You have a points dizzy or a HEI type?

leaving key on points dizzy is a problem

I assume you have the AUX + battery cable (smaller one) going to the buss terminal near RF fender
It's an HEI. If you mean positive cable, yes it has a wire that connects to the junction block, apparently for the battery gauge.
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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 of OEM identifications and part numbers, all 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
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Old 10-18-2022, 10:46 PM   #6
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Re: Where does the negative battery cable wire go?

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Originally Posted by 71CHEVYSHORTBED402 View Post
It's an HEI. If you mean positive cable, yes it has a wire that connects to the junction block, apparently for the battery gauge.
That wire to the junction block is the power for everything in the truck except the stater motor
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Old 10-18-2022, 11:58 PM   #7
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Re: Where does the negative battery cable wire go?

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That wire to the junction block is the power for everything in the truck except the stater motor
Hmm. I thought it was strictly for battery gauge. Thank you.
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Old 10-19-2022, 01:42 AM   #8
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Re: Where does the negative battery cable wire go?

Negative cable bolts to the engine block.
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Old 10-19-2022, 10:29 AM   #9
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Re: Where does the negative battery cable wire go?

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Negative cable bolts to the engine block.
the main - battery cable, yes, goes to block. The secondary - cable being discussed goes to the PS fender (pics)

+ cable the main goes to starter with the secondary going to the buss on PS fender
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Old 10-19-2022, 12:27 PM   #10
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Re: Where does the negative battery cable wire go?

The assembly manual shows the negative terminal of the battery being connected only to the engine. From there, the ground connection to the cab is made through two grounding straps from the valve covers to the firewall. The cab is then connected to the frame via another grounding strap at the front right cab mount.
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Old 10-19-2022, 01:29 PM   #11
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Re: Where does the negative battery cable wire go?

Beyond what the trucks came with from factory, as noted above illustration, negative battery cables made with a secondary ground wire, that wire typically connect to the PS fender. While the stock - cable may not have had one, most aftermarket/replacement ones do.
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Old 10-19-2022, 02:52 PM   #12
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Re: Where does the negative battery cable wire go?

Good information. Per the manual my negative cable mounts on my BBC using the lower A/C compressor bracket's bolt nearest the fuel pump. It shows a washer of some sort as well, probably a ground washer. I believe it routes through the accessories handle on the front a/c bracket.

Interest PJ, Greg and I were just talking about the clips for the positive cable. I believe my Chevy had two off the oil pan, and one off the frame rail. For what worth, the clips on the frame rails vary, same their locations but close enough.

I'm still trying to understand more about the junction block. Takes three wires:

1. Red: from alternator, with fusible link. I thought this was for the battery gauge, but? Seems it serves to charge the battery, as well. Heck, I don't know.

2. Black: to cab with in-line fuse. I thought this served for the battery gauge only. What does it do?

3. Red: from positive battery terminal, for power some place and battery gauge
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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 of OEM identifications and part numbers, all 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; 10-19-2022 at 05:49 PM.
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Old 10-19-2022, 06:13 PM   #13
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Re: Where does the negative battery cable wire go?

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Originally Posted by 72SB View Post
the main - battery cable, yes, goes to block. The secondary - cable being discussed goes to the PS fender (pics)

+ cable the main goes to starter with the secondary going to the buss on PS fender
My bad. I did not thoroughly read the first post. I've never seen the need for a secondary tap on the Negative cable. Some pre-made cables do come with it. I just figured that was for foreign cars with a ''Positive Earth'' system.
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Old 10-20-2022, 10:33 PM   #14
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Re: Where does the negative battery cable wire go?

The smaller red 3) from the battery should be connected to a fusible link that is then connected to the junction.
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Old 10-21-2022, 12:00 AM   #15
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Re: Where does the negative battery cable wire go?

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The smaller red 3) from the battery should be connected to a fusible link that is then connected to the junction.
Added, thank you, but I think that's #2
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Old 10-21-2022, 12:06 AM   #16
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Re: Where does the negative battery cable wire go?

#2 is the 12awg wire that is part of the harness that runs over the radiator to the alternator and fuse panel, right? The fusible link is not in that wire.
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Old 10-21-2022, 12:38 PM   #17
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Re: Where does the negative battery cable wire go?

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#2 is the 12awg wire that is part of the harness that runs over the radiator to the alternator and fuse panel, right? The fusible link is not in that wire.
Perhaps some variances? I'm holding the wire off the positive cable, it's just a wire.
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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 of OEM identifications and part numbers, all 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
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Old 10-21-2022, 12:44 PM   #18
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Re: Where does the negative battery cable wire go?

That's interesting. I've never seen a fusible link like that. Mine looks like a regular wire and is spliced onto the wire coming from the battery terminal. Is your headlight harness a factory original?
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Old 10-21-2022, 12:54 PM   #19
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Re: Where does the negative battery cable wire go?

Great information
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Old 10-21-2022, 01:03 PM   #20
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Re: Where does the negative battery cable wire go?

The information in the assembly manual doesn't always match up with reality, but here are a couple pages that show the location of the fusible link. There's a note on there that says, "FUSIBLE LINK (PART OF BATTERY POSITIVE CABLE ASM)." The schematic shows it that way as well.
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Old 10-21-2022, 01:04 PM   #21
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Re: Where does the negative battery cable wire go?

Hmm, interesting. On my 72, the auxiliary negative wire is routed to the core support. It attaches to the same bolt the headlight negative wire uses.
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Old 10-22-2022, 03:46 PM   #22
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Re: Where does the negative battery cable wire go?

I have a replacement front lights harness,, but my old one has the fused link in the harness as well.

I wondered about mounting the negative cable,s ground wire with the headlight ground. I'm not near the truck, if I recall the headlight ground is a 5/16 screw, seems the battery wire,s terminal takes a 1/4 .
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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 of OEM identifications and part numbers, all 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
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Old 10-22-2022, 06:32 PM   #23
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Re: Where does the negative battery cable wire go?

I know it's not factory but I connect my ground to the engine block and add a second ground from the engine block to the frame. You can't have too many grounds on these old trucks.
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Old 10-23-2022, 12:10 AM   #24
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Re: Where does the negative battery cable wire go?

Quote:
Originally Posted by pjmoreland View Post
That's interesting. I've never seen a fusible link like that. Mine looks like a regular wire and is spliced onto the wire coming from the battery terminal. Is your headlight harness a factory original?
Factory originals look pretty much like a length of regular wire that usually has shrink tube at each end. A lot of the aftermarket fusible links look like the one he showed.
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Old 10-23-2022, 12:42 AM   #25
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Re: Where does the negative battery cable wire go?

Your secondary ground wire off the battery cable just goes to a spot on the body where you are comfortable with putting it. It serves as a more direct ground to the battery for the lights and for other accessories.

The purple wire has to go to the S post of which ever solenoid you are going to use to energize the starter. Without it properly connected the solenoid isn't going to function and you won't be able to crank the engine.

You don't need the resistor bypass wire from the R post on the solenoid with HEI.

When I changed my 71 to HEI I ran the wire for the hei from one of the hot when the key is on pins on the Fuse block so I could run a heavier gauge wire to the hei.

Make sure that you have the correct HEI wire terminal to plug into the HEI rather than just use a female slide. A female slide will slide at an inopportune time if it loosens up just a tad. Been there done that.
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