Where does negative battery cable ground wire attach?

[tophat36]

I would like to replace my negative battery cable so that I can fix this jankity ground wire. When I replace it, where does this ground wire attach?

Also, could this existing ground being mangled and unattached cause issues with starting? It takes me a while to get started if it’s the first time of the day. After that, no issues with delayed starting through the day.

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Thank you!

My truck (Gus Gus)
1980 GMC C20 3/4 ton Longbed Wideside
Sierra Classic Camper Special
350 5.7L V8 TH-400
14 bolt full float
HD chassis

 

[Originalthor]

The main ground should go to the intake or close to the alternater bracket(someone will know exactly for the year here) and there also should be wire going to the radiator support.

 

[SirRobyn0]

Yea, I mean the most important thing is that the big wire is attached to somewhere on the block of the engine that the starter and alternator can use without passing though to much. Usually not the intake, because the starter would encounter some resistance, but typically a bolt on the passenger side of the block.... I'm not saying GM did or didn't use the intake manifold, I'm just saying the block is best. And the smaller wire to the core support.

When you install the new cable be sure that you sand or steel wool the metal until it's clean and rust free, then coat the bolt, and the metal with a thin layer of dielectric grease.

 

[75gmck25]

The battery ground wire on my ‘75 is bolted to a hole in the top of the alternator bracket. Easy to reach and definitely well grounded to the engine.

I also have a ground strap from the top of the frame near the fuel pump over to the block, and a ground from the back passenger side corner of the block over to the firewall.

Your positive battery cable should run down to near the fuel pump, and then along the edge of the oil pan to the large lug on the starter. That starter lug connection can loosen up, and it’s in a hard to reach area that seldom gets checked. The main power lead for your fuse box is also connected to the starter.

 

[fast 99]

Should also have a strap from block to body. Redundant grounds are your friend.

 

[tophat36]

Thank you for all the input, is in summary this is what y’all are saying ….?

My red cable is the positive and it goes to the starter, which is down by the fuel pump, and less accessible. It also connects to and is the main supply to the fuse box, where all the harnesses, etc get power.

The black cable is the negative and also the main ground cable. This main ground should go to the alternator bracket, but could also go to the intake in some cases, but sounds like the alternator bracket is better and more standard. Additional smaller ground strap (the one that I have broken currently) coming off the black negative terminal should also go to radiator core support.

Grounds are good, friendly, and it’s okay if they’re redundant lol. There can be additional ground straps connecting different parts of the truck (not connected to the battery) such as:
- frame to engine block
- engine block to body (is body the same as frame?
- firewall to frame

When installing grounds make sure it’s raw metal to metal and use a little dielectric grease for those connections.

Additional questions -
1) Can you give me examples of body vs frame vs engine block vs firewall? Most unclear to me are block and firewall.

2) Does the small broken ground wire I have that isn’t connected to the radiator core support, could this be the cause of my difficulty starting the truck when it has been sitting for a day?

Thank you!

My truck (Gus Gus)
1980 GMC C20 3/4 ton Longbed Wideside
Sierra Classic Camper Special
Charcoal w/ mystic interior
350 5.7L V8 TH-400
14 bolt full float
HD chassis

 

[RaisedK5]

Here's the batt cable routing from 75. Note the headlight grounding screw location. That's where that broken one went.

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[timbritton]

I was having trouble with mine. I just about bought a new starter. By accident I found that I had to run a ground cable to the starter mounting bolt. Problem solved. I hope this helps.

 

[Bextreme04]

Thank you for all the input, is in summary this is what y’all are saying ….?

My red cable is the positive and it goes to the starter, which is down by the fuel pump, and less accessible. It also connects to and is the main supply to the fuse box, where all the harnesses, etc get power.

The black cable is the negative and also the main ground cable. This main ground should go to the alternator bracket, but could also go to the intake in some cases, but sounds like the alternator bracket is better and more standard. Additional smaller ground strap (the one that I have broken currently) coming off the black negative terminal should also go to radiator core support.

Grounds are good, friendly, and it’s okay if they’re redundant lol. There can be additional ground straps connecting different parts of the truck (not connected to the battery) such as:
- frame to engine block
- engine block to body (is body the same as frame?
- firewall to frame

When installing grounds make sure it’s raw metal to metal and use a little dielectric grease for those connections.

Additional questions -
1) Can you give me examples of body vs frame vs engine block vs firewall? Most unclear to me are block and firewall.

2) Does the small broken ground wire I have that isn’t connected to the radiator core support, could this be the cause of my difficulty starting the truck when it has been sitting for a day?

Thank you!

My truck (Gus Gus)
1980 GMC C20 3/4 ton Longbed Wideside
Sierra Classic Camper Special
Charcoal w/ mystic interior
350 5.7L V8 TH-400
14 bolt full float
HD chassis

What do you mean with "difficulty to start"? Is it not cranking? Cranking slow? Cranking slow but just not firing off? Sputtering but not catching? If its crank, but not firing for many seconds of cranking, I would bet you need to set your carb up properly. It is most likely a choke/high idle problem.

 

[Scott91370]

Grounds are good, friendly, and it’s okay if they’re redundant lol. There can be additional ground straps connecting different parts of the truck (not connected to the battery) such as:
- frame to engine block
- engine block to body (is body the same as frame?
- firewall to frame

When installing grounds make sure it’s raw metal to metal and use a little dielectric grease for those connections.

Additional questions -
1) Can you give me examples of body vs frame vs engine block vs firewall? Most unclear to me are block and firewall.

2) Does the small broken ground wire I have that isn’t connected to the radiator core support, could this be the cause of my difficulty starting the truck when it has been sitting for a day?

1) Body will be bed, cab, fenders and hood. Frame is the large metal part that everything mentioned, plus the engine and suspension are bolted to.

2) That small broken wire should not cause any starting/running issues. It will usually cause forward light problems because the core support has rubber mounting bushings and paint that keep it from getting as good ground without using that wire.

 

[Dryriver1]

Thank you for all the input, is in summary this is what y’all are saying ….?

My red cable is the positive and it goes to the starter, which is down by the fuel pump, and less accessible. It also connects to and is the main supply to the fuse box, where all the harnesses, etc get power.

The black cable is the negative and also the main ground cable. This main ground should go to the alternator bracket, but could also go to the intake in some cases, but sounds like the alternator bracket is better and more standard. Additional smaller ground strap (the one that I have broken currently) coming off the black negative terminal should also go to radiator core support.

Grounds are good, friendly, and it’s okay if they’re redundant lol. There can be additional ground straps connecting different parts of the truck (not connected to the battery) such as:
- frame to engine block
- engine block to body (is body the same as frame?
- firewall to frame

When installing grounds make sure it’s raw metal to metal and use a little dielectric grease for those connections.

Additional questions -
1) Can you give me examples of body vs frame vs engine block vs firewall? Most unclear to me are block and firewall.

2) Does the small broken ground wire I have that isn’t connected to the radiator core support, could this be the cause of my difficulty starting the truck when it has been sitting for a day?

Thank you!

My truck (Gus Gus)
1980 GMC C20 3/4 ton Longbed Wideside
Sierra Classic Camper Special
Charcoal w/ mystic interior
350 5.7L V8 TH-400
14 bolt full float
HD chassis

Hello TH36! I hope all is well.

I would disconnect your ground wire to the battery if you are going to check or try tightening the red cable going to the starter... just in case you hit the frame or case of the starter with your wrench you will not get a big spark, startled, burnt, or hurt trying to pull away too fast if in case you do short to the frame, case, etc...

I also agree that the small floating ground will not cause trouble with your start-up.

Keep us posted.

Be well and stay safe out there.
Best wishes to you and all of your loved ones always!

Dryriver1

 

[tophat36]

What do you mean with "difficulty to start"? Is it not cranking? Cranking slow? Cranking slow but just not firing off? Sputtering but not catching? If its crank, but not firing for many seconds of cranking, I would bet you need to set your carb up properly. It is most likely a choke/high idle problem.

Here’s a short clip, just doesn’t start right up like it does after it has been started already.

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[tophat36]

So I went and took another look to see what grounds I could find tonight. Found where the broken ground wire should connect be the headlight, so that was cool to find the broken wire tucked in there.

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Found a ground on the passenger side by firewall going back behind whatever that little cylinder thing is.

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Only other one I could find in the dark was coming from under the battery toward the center of truck. Will look at the starter connection when it’s light out. Thanks for all of the help and great details!

 

[Rusty Nail]

Jankity!

Open the hood next time ya run through the car warsh huh?

"The Big 3 Upgrade"

I'm suprised this hasn't been added to GMSB yet. I've been going to do a write up on this for some time now, but haven't gotten to it. So I'll just assemble the information from a few different sources and if someone wants to do this upgrade to their square then post up your pics as you complete...

www.gmsquarebody.com

 

[tophat36]

Jankity!

Open the hood next time ya run through the car warsh huh?

"The Big 3 Upgrade"

I'm suprised this hasn't been added to GMSB yet. I've been going to do a write up on this for some time now, but haven't gotten to it. So I'll just assemble the information from a few different sources and if someone wants to do this upgrade to their square then post up your pics as you complete...

www.gmsquarebody.com

lol, jankity yes (unsure of correct spelling) …I sure hope you’re not talking’ smack about my old dirty engine compartment, the time will come when all will be nice and clean, that time is not today. Thanks for the great link.