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What is this Ground Wire for?

  • Thread starter Thread starter TonyMano
  • Start date Start date Feb 10, 2026

TonyMano

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#1
  • Feb 10, 2026
  • #1
For my 1990 Ford Mustang 5.0, What is this Ground Wire for?
 
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X-cam34

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#2
  • Feb 10, 2026
  • #2
battery negative to engine block ground cable.
 

TonyMano

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#3
  • Feb 10, 2026
  • #3
Can you Give me a Picture of Where is Goes on the Engine?
 
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X-cam34

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#4
  • Feb 10, 2026
  • #4
View: https://www.youtube.com/watch?v=uVtGn8Qy_ZU
View: https://www.youtube.com/watch?v=1xopC9NhX6o
 
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TonyMano

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#5
  • Feb 11, 2026
  • #5
I Don't Think that's the Negative Battery to Engine Block Ground Cable.

The Negative-Battery Ground Cable would Look like This:

 

Noobz347

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#6
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Is it your assumption that nothing on that car has been changed or modified since it was new?
 

TonyMano

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#7
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All Stock.
 

gkomo

now i can hopefully expect to receive the shaft
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#8
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  • #8
Where did you get the cable from?
 

Noobz347

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#9
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It looks like it came from the "Help" section at the local Autozone.
 

TonyMano

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#10
  • Feb 11, 2026
  • #10
gkomo said:
Where did you get the cable from?
Click to expand...
I Took it Out from the Engine bay.
 

General karthief

wonder how much it would cost to ship you a pair
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#11
  • Feb 11, 2026
  • #11
TonyMano said:
I Took it Out from the Engine bay.
Click to expand...
Right next to Tampa Bay??
Seriously, that's pretty general, the only cable like that I've seen is the cable from the solenoid to the starter, it could have been swapped to a bolt on style battery clamp but
I don't have eyes on the engine bay
 

JD1964

there is enough sticking out to grab on to
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#12
  • Feb 12, 2026
  • #12
Maybe it’s an additional ground strap that someone had previously installed. Like between the block and the K member for instance. Usually from motor mount bolt on block to motor mount bolt on k member
 
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KRUISR

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#13
  • Feb 12, 2026
  • #13
I agree it looks like a cable from the auto parts store. Might have been used to replace the ground from the cylinder head to firewall. Those exposed braided grounds do fatigue and corrode over time.,

Either way, it really doesn't matter. You will have the battery to engine ground (the one you pictured in post #5) and at least one from the back of the cylinder head to firewall. You could do additional ones with no issue. Like some have said, lower engine block to k-member, alternator bracket to fender apron on passenger side, ....

Just be aware when routing additional cables of rotating and hot parts. Most people will try to keep additional grounds out of sight or less visible, but it really doesn't matter.
 
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TonyMano

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#14
  • Feb 12, 2026
  • #14
KRUISR said:
I agree it looks like a cable from the auto parts store. Might have been used to replace the ground from the cylinder head to firewall. Those exposed braided grounds do fatigue and corrode over time.,

Either way, it really doesn't matter. You will have the battery to engine ground (the one you pictured in post #5) and at least one from the back of the cylinder head to firewall. You could do additional ones with no issue. Like some have said, lower engine block to k-member, alternator bracket to fender apron on passenger side, ....

Just be aware when routing additional cables of rotating and hot parts. Most people will try to keep additional grounds out of sight or less visible, but it really doesn't matter.
Click to expand...
Thanks. The Previous Owner must have Installed that Many Years Ago.
 

AeroCoupe

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#15
  • Feb 13, 2026
  • #15
That would make me wonder why. Might want to do voltage drop tests on the remaining cable to see if that wasn’t a bandaid for an existing problem.
 
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Praetorious

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#16
  • Feb 14, 2026
  • #16
KRUISR said:
I agree it looks like a cable from the auto parts store. Might have been used to replace the ground from the cylinder head to firewall. Those exposed braided grounds do fatigue and corrode over time.,

Either way, it really doesn't matter. You will have the battery to engine ground (the one you pictured in post #5) and at least one from the back of the cylinder head to firewall. You could do additional ones with no issue. Like some have said, lower engine block to k-member, alternator bracket to fender apron on passenger side, ....

Just be aware when routing additional cables of rotating and hot parts. Most people will try to keep additional grounds out of sight or less visible, but it really doesn't matter.
Click to expand...
"Those exposed braided grounds do fatigue and corrode over time" boy thats the truth,i once had a issue with that ground strap that i would soon like to forget,i would come to a stop and once i hit the brakes the radio would die,then the car started dying everywhere and wouldn't start for a bit, finally after 2 months of this and ready for a asylum i was at work messing with the car and this coworker said "man your car just arced towards the firewall when you tried to start it" i could have kissed him on the spot and i dont go for that,lol,after i replaced that strap i never had trouble again,EVER.

The piece that started this thread reminds me exactly of that ground strap,not how the oem one looks like but those 2 lugs and the shape of it,definitely thats where my vote would go for location.
 
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Bullitt347

I have been doing it wrong this whole time
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#17
  • Feb 14, 2026
  • #17
GM to this day still use braided, non shielded (no covering for the braid) ground straps on their vehicles.
Half the time a vehicle comes in for a no crank, no start it is because that ground cable is excessively corroded, usually in half.
Think the starter is bad? Nope, it is a bad ground strap. And it is almost always the one that goes from the back of the block to the body/firewall.
 
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Praetorious

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#18
  • Feb 14, 2026
  • #18
That's gospel right there,funny thing is, some cars are really susceptible to this and some are not, i was working on a buddies car once ,i think it was a Dodge Neon, he wasn't known for being tidy or taking care of his vehicles,i started to get under the car and i see this thing thats hanging off the car and looks like its been dragging since the Depression and i asked him"hey man, what is that? and he replied ,oh thats a ground strap" ha ha ha ha
 
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