question about grounding a hu

[redfred18t 10+ year member]

Hey guys. I have a quick question about grounding a head unit. I've had a kenwood excelon HU for about 4 years now, but I just recently picked up a p800prs.

I've noticed that the p800prs's ground wire has a little ring terminal on it. Is it necessary to ground it to the chassis or can I just ground it though the harness? Also, if I remember correctly, the kenwood is grounded through the harness but it's been like 2 years since I went back there haha.

This is on a 01 vw jetta btw

Thanks guys

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[revrider1 5,000+ posts]

Just ground it, Id do to chassis to be safe. Always better than taking it back out

 

[redfred18t 10+ year member]

Sounds good redrider

another quick question, can I extend the lead for the ground? I know theres distribution block in my car under the dash, and there is a ground there. I just dont know if the supplied lead is long enough to reach it.

Thanks again

 

[dragnix 5,000+ posts]

it's best to keep the ground short, unless you're grounding to the battery or something //content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif

Isn't there bare metal behind the dash?

 

[Ferendon 10+ year member]

Just ground it to the nearest pure metal structure. And by pure metal, I mean no pot metal.

That harness may or may not have a ground in it, anyways.

 

[redfred18t 10+ year member]

it's best to keep the ground short, unless you're grounding to the battery or something //content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gifIsn't there bare metal behind the dash?

I dont remember. It's been a while since I've peeked in there.

 

[funkyab 10+ year member]

i ground everything to the battery. If we are running wire for any reason, might as well terminate everything properly.

 

[theothermike 10+ year member]

why ground to the battery when the Ground for the car is throughout its chassis / body / frame. the battery gets it ground from that so why shouldnt ur equipment. ground behind dash on a bare metal spirt. remove and rust, dirt, grime, paint etc...

secure it tightly then apply vaseline or a sort of rust resister type of coating.

Mike-

 

[x2o 10+ year member]

why ground to the battery when the Ground for the car is throughout its chassis / body / frame. the battery gets it ground from that so why shouldnt ur equipment. ground behind dash on a bare metal spirt. remove and rust, dirt, grime, paint etc...
secure it tightly then apply vaseline or a sort of rust resister type of coating.

Mike-

Oh man...Not another one of these arguements... //content.invisioncic.com/y282845/emoticons/hide.gif.2d479cfd917eedfe201353b91522ceab.gif

 

[redfred18t 10+ year member]

Oh no I dont want to start a fight!

I'll try to ground it to that distribution block I was talking about (heres a pic about it)

okay, vwvortex isn't loading so I cant get the pic. fail

 

[x2o 10+ year member]

Oh no I dont want to start a fight!
I'll try to ground it to that distribution block I was talking about (heres a pic about it)

okay, vwvortex isn't loading so I cant get the pic. fail

I would honestly just ground it to a metal piece behind the dash where the radio goes in.. Just about every car I've ever put a headunit into has a metal brace or two that connect to the chassis behind the hole for the headunit and it works great for a ground.

Extending your ground wire is not the ideal thing to do, but I'm sure it will work if you go out to the distro. Your just making it more work then it needs to be //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[redfred18t 10+ year member]

Thanks again everyone. I'm going to try to prep all the wiring tonight so I can have an easy day tomorrow just swapping the new HU in.

 

[theothermike 10+ year member]

POSTED BY CHAD ON DIYMA. IMO ONE OF THE MOST HIGHLY REGARDED INDIVIDUALS IN CA SCENE.

I (and others) look at the "ground" as a point of 0V reference where as you (and others) look at the chassis as a conductor, which IS a conductor as is any ground SYSTEM. The system is what gets people, yes the neg battery terminal in our case is part of the SYSTEM, just like the earth is part of a functional ground system for discharge. Calling the neg battery terminal ground (or positive) only names part of the big picture whereas when you look at the chassis and anything attached to it as the ground encompasses the whole thing.

I see the ground as the chassis, the point at which all grounds or parts of the ground system attach, just as in discharge and PD potential grounding where the earth is the ground.

 

[helotaxi 5,000+ posts]

There is NO "ground" in the car. Not in the engineering sense of the word. The chassis is nothing more than a large buss bar for the neg side of the system. In a grounded system (a real grounded system with a connection to earth) the ground is there to protect people working on the system by dissipating stray charge and conducting shorts to earth to keep people from getting shocked. A ground is only a safety feature, it is not part of the circuit and the circuit is complete without it. The "ground" in the car is an essential part of the circuit and is the return path to the voltage source. The neg post of the battery and the case of the alternator (which should be connected making them electrically the same) are the points of zero potential and your goal should be to make the best conducting path to those points possible.

 

[jrwalte 10+ year member]

There is NO "ground" in the car. Not in the engineering sense of the word. The chassis is nothing more than a large buss bar for the neg side of the system. In a grounded system (a real grounded system with a connection to earth) the ground is there to protect people working on the system by dissipating stray charge and conducting shorts to earth to keep people from getting shocked. A ground is only a safety feature, it is not part of the circuit and the circuit is complete without it. The "ground" in the car is an essential part of the circuit and is the return path to the voltage source. The neg post of the battery and the case of the alternator (which should be connected making them electrically the same) are the points of zero potential and your goal should be to make the best conducting path to those points possible.

x2. A chassis is not a ground. it's just a negative path and a cheap/easy way to complete the circuit between a battery and an alternator.