Ground strap

[stangguy]

My 1998 Mustang base model V/6 has a ground strap running from the body to the hood back by the passenger side hood hinge. There are absolutely no electrical things in the hood, so why the ground strap? Is it just for some cars that do have a light or something there? Doesn't really matter, but just curious.

 

[wymi516]

A ground strap is to ground the hood. When you're driving, the friction between the hood and air can cause a build up of static electricity. A ground strap grounds it so the charge can't build up and arc.

 

[stangguy]

A ground strap is to ground the hood. When you're driving, the friction between the hood and air can cause a build up of static electricity. A ground strap grounds it so the charge can't build up and arc.

Wow, I never heard of that before. So do all vehicles have that. Where would it arc to?

 

[ka9mnx]

Wow, I never heard of that before. So do all vehicles have that. Where would it arc to?

Across your body!

 

[ka9mnx]

A ground strap is to ground the hood. When you're driving, the friction between the hood and air can cause a build up of static electricity. A ground strap grounds it so the charge can't build up and arc.

Absolutely correct but to be correct you are bonding the hood to the body making everything, electrically, common to each other.

 

[stangguy]

Across your body!

So I could get a shock if touching the hood if it weren't there? I am sure not all vehicles have that, and I have never got a shock from a hood in my life.

 

[ripcord]

I don't know all of the reasons to ground the hood to the body, but I suspect it's there at least partially to reduce radio frequency interference from the engine compartment. I've had cars with a little "L" bracket that connected the bottom of the hood to the firewall, electrically, and noticed a lot of extra static on the radio if the hood was up and the engine was running.

 

[ka9mnx]

I don't know all of the reasons to ground the hood to the body, but I suspect it's there at least partially to reduce radio frequency interference from the engine compartment. I've had cars with a little "L" bracket that connected the bottom of the hood to the firewall, electrically, and noticed a lot of extra static on the radio if the hood was up and the engine was running.

Exactly. All body panels are bonded electrically to create a shield, or crude Faraday cage, to protect sensitive electronics within the vehicle from outside sources.

 

[ka9mnx]

So I could get a shock if touching the hood if it weren't there? I am sure not all vehicles have that, and I have never got a shock from a hood in my life.

Highly unlikely.

 

[stangguy]

Oh sure, the radio and stuff like that. Makes sense, I didn't think of that. NOW I get it. Thanks all.

 

[Dinoburner]

The strap could also be used to control RF interference.

 

[OilUzer]

Lightning

 

[willbur]

Highly unlikely.

Helicopter blades do. Supposedly, in a rescue one should let the cable first touch water or ground before grabbing it. The hood hinge mechanism probably conducts that induced static charge to the body anyway so it seems redundant

 

[Kira]

A thin band of copper was was attached to the firewall of a car I owned.
It was 1/2" wide and maybe 4" long. It pointed up and bent lazily into the air where the rear edge of the hood would contact it upon closing.
It had little, jagged-edged punctures (like a cheese grater) toward the contact end for better conductivity.

 

[stangguy]

A thin band of copper was was attached to the firewall of a car I owned.
It was 1/2" wide and maybe 4" long. It pointed up and bent lazily into the air where the rear edge of the hood would contact it upon closing.
It had little, jagged-edged punctures (like a cheese grater) toward the contact end for better conductivity.

A thin band of copper was was attached to the firewall of a car I owned.
It was 1/2" wide and maybe 4" long. It pointed up and bent lazily into the air where the rear edge of the hood would contact it upon closing.
It had little, jagged-edged punctures (like a cheese grater) toward the contact end for better conductivity.

I remember those copper straps on some cars also. Didn't think of them till now.

 

[Rhymingmechanic]

These explanations make sense, but the hood is bolted to the hinges are bolted to the body. Why is a separate ground required? Paint in the bolt holes? Clearly, it must be required if the automaker spends an extra 5 cents on it.

 

[ka9mnx]

Hinges do no always make a positive electrical connection making the situation worse. An intermittent connection can actually become a transmitter and cause EMI.

 

[willbur]

Hinges do no always make a positive electrical connection making the situation worse. An intermittent connection can actually become a transmitter and cause EMI.

Everywhere on a car bolts into the chassis or engine provide grounds- no problem. Why would a hood with multiple bolts into the body via springs be any different? Would like to know, not being argumentative

 

[DGXR]

So I have a high tech faraday hood... and so does everyone else.

 

[another Todd]

Nope, wouldn't work as a faraday cage.