tracyk

I'm guessing this is not an exceptionally important ground on a 99 Cherokee simply because the one I have is frayed/cracked/rotting but I'm still able to get from point A to B. I picked up a new one to swap it out, but I should probably ask:
The pic shows the wire/braid (?) as presently installed. BUT I had it disconnected for a gasket change last weekend and was not careful to note its position. So I'm not sure if I put it back as it was or if it needs to be (or can be) behind these other wires (and therefore potentially up against the firewall). Related question - my replacement is a tad longer (maybe a few inches?), so when I put that one in, do I need to take special care with its placement since there may be some play in it?
Bottom line: I'm not sure what exactly this guy should be or not be touching or laying against in there.

THANKS THANKS in advance!

tracyk

AND CRAP!!! SORRY FOR SIDEWAYS PIC... NOW DO YOU SEE WHY EVERYTHING IS SO DIFFICULT FOR ME?????? haha

XJlimitedx99

It looks fine to me

tracyk

So, if the replacement if longer, don't worry about it? Just let it go where it pleases?

Whiplash

looks good to me too...
if you replace it stay with the same type, not a rounded wire...those flat ones are way better, outer surface area is key

travs2448

i heard these are only to ground the radio from static anyway

Pelican

Outer surface area has nothing to do with grounds in 12v direct current circuits. A ground is a ground subject of course to the wire being of adequate gauge to carry the projected current in the circuit.

Cruiser54 is the GROUND KING. You can look up ground and other cable replacement and maintenance on his site.

Length is of no consequence as long as it isn't so long that it might get caught up in uninsulated electrical connections -- certainly not a problem in this case.

I can't tell from your pic, but you do want to scrape/sand away any paint or corrosion down to shiny bare metal where the connections ate made to the block and firewall. It can be difficult to get to the connection on the block and many are hooking the ground up to some other convenient nut in the area of the fuel rail.

tracyk

Wait, 12V? I asked for 4 awg based on some old CF threads I read through today. I'm hoping I got the right thing (I won't actually get around to it til the weekend)

And I'm hoping my last-weekend frustration with that pita bolt (getting it out of the way to get vc off) will benefit me now. It was so dirty and rusted at the top that I wasted at least an hour cleaning just that area and using WD40 corrosion specific spray on the bolt/waiting/brushing/working the bolt up ONE thread at a time (repeat ad nauseum). Annoying because I realized then that I should swap that strap out but didn't have one nor the extra time to figure out the correct product. Erg.
Again, many thanks all.

BlueRidgeMark

You are just fine. Two different things. 4AWG is the SIZE of the wire. (And I'm pretty sure that braid is NOT 4 AWG, but it's fine.) 12v is the voltage of the circuits in most cars.



And the sea bird fella is correct - outside surface isn't relevant to 12vdc circuits. That matters in alternating current, but it's frequency dependent. The higher the frequency, the more it matters. Even at 60 Hz, like your house power, it's not really a big factor. It's called, "skin effect", by the way.

Pelican

4 AWG is fine whether it is braid or conventional, bare or insulated, round or flat cable.

Of no consequence whatsoever for your project, but the point about outer surface area has to do with high frequency AC circuits where current flows on the surface of the conductor. DC current that we are concerned with flows through the entire conductor.

Braided cable is very flexible and is convenient for short grounds in this area where the motor moves constantly in relation to the firewall. I do not know if there is another reason for using the braid here, but all other stock grounds on the XJ are conventional round insulated cable and you can certainly use the same cable in the block to firewall ground (which many are doing now).

I'm not familiar with corrosion specific WD40 but you should be fine if you get it off of the area where the cable connects.

Edit: Crossed w/BlueRidgeMark

tracyk

Cool, thanks for the info. These posts are all really helpful.

salad

For reference the later model literature - including our 1999s - does not list this as a "ground", per se. It can break and your late model XJ will still run. This is referred to as an interference suppression strap and helps keep the radio behaving nicely.

As far as replacement goes, that braided crap is cheap and very flexible. It's not a "proper circuit ground" so doesn't need to be as robust. Pennies matter when you build over a million of these! Replacement wire can be whatever, 6 AWG to keep things consistent I would suggest as a minimum size. Get at least a foot to give it lots of room to flex without breaking.

Whiplash

guess i shoulda specified it was an RF ground?? RF does travel on the surface

BlueRidgeMark

Yes, but the concept of an RF ground is.... interesting. A cable that is a dead short to DC might be a high impedance to an RF signal. Some antennas have a loop of solid conductor from the antenna to ground, for example.

salad

I just used an ignition wire I had floating around, no spark plug noise here lol.

In my mind it's clearly engineered to be effective at a certain price point - overbuilding rarely makes the situation worse!