3G ground question

as i continue to track down the idle surge gremlin on my beloved Bronco, I read all sorts of interesting tidbits, came across this, and I am sure that I do not have the 3g ground this way, can someone show me a pic on how, or explain on how pls?

this is from stangnet......
Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.

That doesn't make any sense to me. Here's a post I put up a few days ago and Mono posted some nice pics.

http://www.classicbroncos.com/forums/showthread.php?t=158222

I know the BC diagram says that you should ground the 3G from the back of the unit to the chassis but I'm not aware of anyone doing that since the bolts ground it to the block and the block should have one or two ground straps to the frame and or firewall.

If your starter works you already have a decent engine ground back to the battery. As long as the alternator is mounted to the engine through clean bare metal it isn't your problem. Also, the alternator shouldn't be charging so much that it trys to pull the idle speed down unless you're recharging a dead battery or winching or trying to turn an electric radiator fan.

NJB71 said:

can someone show me a pic on how, or explain on how pls?

this is from stangnet......
Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.

Click to expand...

Not sure I agree completely with this statement. It states that "battery pigtail ground" connects to the chassis, and that's where you should ground the block. I'm not even sure what is meant by a "battery pigtail ground", although I've seen battery cables with the large (4 ga.) wire and an additional smaller (10 ga?) wire.

A good grounding scheme in any vehicle, including our Broncos, will have the negative battery cable connected directly to the engine block. The largest current draw on the vehicle (besides a winch) is the starter. The current path for the starter is from the + battery connection, through the starter solenoid, down the starter cable to the starter, then to the block, and finally back to the - battery post.

It's also extremely important to have both the body and the frame grounded. I have a small braided ground strap connected from the rear of the intake manifold to the firewall. I also have a much larger ground strap connected to the same place on the block as the negative battery cable, then bolted to the frame.

So, yes, while the 3G (or any alternator) needs to have a substantial ground, I don't like the way that stangnet statement is worded. If you simply connect the negative battery cable to the block you have achieved what is necessary for the alternator.

A winch is not (usually) a consideration in this grounding scheme as most winch manufacturers recommend connecting the + and - of the winch directly to the battery.

sounded strange, just wanted to check

Viperwolf1 said:

If your starter works you already have a decent engine ground back to the battery. As long as the alternator is mounted to the engine through clean bare metal it isn't your problem. Also, the alternator shouldn't be charging so much that it trys to pull the idle speed down unless you're recharging a dead battery or winching or trying to turn an electric radiator fan.

Click to expand...

i know-i am coming across littany of suggestions on idle surge, o2 sensor(didnt realize fusable link was built into them, funny, I installed mine on the bcb shortys, 3" below collector, I used 8' long o2 pigtails, passenger side wouldnt plug in w/o really stretching, i know my o2 was touching header, and i worried I would melt it, i also hear that causes short in fusable link, so I cut the pigtail and soldered an extansion and wrapped it in fiberglass cloth....uggh maybe why i am getting the screwy reading and surge/...I actually have new long pigtail sensor i will swap tonight...see if that helps....then they say MAF w/ large cone filter in engine comp can screw up idle as well, bad or dirty IAC(mines brand new), tps voltage(working on that) i have new IAB(so dont think its that-BUT when ryan sent me a new connector to swap on my harness he sent it w/ 1 wire looped in both ends, same color and on the harness there is a red/and white wire, so I took a guess....another gremlin i created?

NJB71 said:

-BUT when ryan sent me a new connector to swap on my harness he sent it w/ 1 wire looped in both ends, same color and on the harness there is a red/and white wire, so I took a guess....another gremlin i created?

Click to expand...

My VSS connector came the same way. I suppose there's a reason for that... Anyway, look on Ryans site, at the Wiring Harness page, the one that shows the schematics of the efi stuff. That will show you which connection is which. Or, just look in your Probst book...

70_Steve said:

My VSS connector came the same way. I suppose there's a reason for that... Anyway, look on Ryans site, at the Wiring Harness page, the one that shows the schematics of the efi stuff. That will show you which connection is which. Or, just look in your Probst book...

Click to expand...

Ty 70-Steve......Stephen

70_Steve said:

...I'm not even sure what is meant by a "battery pigtail ground", although I've seen battery cables with the large (4 ga.) wire and an additional smaller (10 ga?) wire.

Click to expand...

Yep, that 10ga shorty wire you saw (usually with a butt-connector pre-crimped to it's end) is the "pigtail".
I can't say for sure, but I think the reason they're called pigtails is that a lot of the older short wire connections were delivered all curled up (to shorten them for packaging perhaps?) and looked like little pig's tails. Hence the name.
Don't see too many of those anymore. Just straight ones now.
After awhile it just stuck to any little additional wire pre-installed in a connector or cable end lug.
So when you buy an alternator connector say, it will have pre-installed "pigtails"
Even though they're now straight. Hmm, wonder if some pig's tails are straight? Probably.

Paul