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Vehicle Grounding

#1 User is offline   Rollbar 

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Posted 27 November 2008 - 07:49 AM

Ok, this will hopefully be the end to the grounding problems that some have.

This one give you a 'Binding Post' for all your dedicated ground that come next to keep things working...
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This shows you the correct place for the 'Starter Ground' to be positioned...
Since the starter is the single largest current draw on the vehicle, the large 'Ground Cable' should be attached to one of it's mounting bolts!
DON'T TORTURE THE STARTER!
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Remember, if the starter has a ground, you should probably make a good positive cable connection also...
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4 Ga. WELDING cable is usually the best battery cable, and NAPA has that and the best Crimp on battery terminal ends (not cheap lead bolt on terminals!) you can find about anywhere...
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And don't forget the alternator!
Every single electron your vehicle uses is created in the alternator!
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10 Ga. wire for both the positive and negative to the alternator.
If you use a 10 Ga. wire for the positive, use a 12 Ga. fusible link to protect it.
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Look for a bolt hole on the back of your alternator. Use a 1/2" long (NO LONGER!) bolt to connect your dedicated ground wire!
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Grounding stud.
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Grounding on the motor mount/block.
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Electrically speaking, A jeep is about 6 or 7 parts flying in very close formation, but not actually touching...
So, dedicated ground wires from the 'Binding Post' shown to the major parts or parts groups will keep you from having the 'Mystery' electrical problems you read about so much here....

One dedicated ground should go to the rear of the vehicle.
Tail lights and fuel tank sender.

One dedicated ground should go to the dash panel, where all your gauges and panel lights are, and some switches ground through that panel.

One dedicated ground should go to the grill shell where all your front end lights ground.

One dedicated ground should go to the engine head(s) and continue over to the 'Black' wire on the ignition module so both the high voltage and low voltage from the ignition gets a ground...
You will find your engine gauges work better when the engine is properly grounded also!

Run one dedicated ground to the body 'tub' and to the frame.
Keeps things like fan blower motor working and stuff like that.

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Some may ground to the block & here is what can happen.

If you "Ground" to the block, the current has to fight it's way from the starter,
through the corroded aluminum starter frame,
through the rusty mounting bolts,
through the corroded aluminum bell housing,
through the rusty bell housing bolts,
through the rusty engine block flange bolt holes,
through the cast iron engine block (cast iron isn't that great of a conductor),
through the rusty 'Grounding' bolt,
through corroded 'Ground Wire' terminals,
through a 22+ year old 'Ground Cable',
through a corroded battery connector connection,
through a corroded connector to battery terminal...

Let's not forget the thermal expansion that happens when all the bolts get hot and expand, releasing the terminals/connections, making them loose...

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Same for the head(s).
With a stock Jeep/Motorcraft/DuraSpark ignition...
The Secondary, Or 'High Voltage' is looking to ground 18,000 to 25,000 volts to a head that is sitting on a non conductive layer of gaskets,
Rusty bolts or bolts with sealer on them.

The ENTIRE primary side of the ignition (Low Voltage) is the Ignition coil, Module are trying to ground through a single wire that is anchored to the distributor...

NOW,
The distributor is aluminum housing and is 22+ years old, that means it's corroded,
The distributor clamp is a rusty bolt in a rusty bolt hole, and it's a painted or rusty piece of metal on a corroded distributor housing and the other end anchors on a painted or rusty engine block.
If you are counting on the MOVING distributor or oil pump connections, DON'T!
Vibrating/oil covered metal is NOT a reliable connection.
Some people think the aluminum housing will ground where it connects to the engine block or timing cover... Not when it's covered in oil film schllac from years of service...

Don't torture your ignition module! Give it a ground!
If you have repeated failure of good quality modules, rest assured it's because of a poor ground to the module.

Don't torture your ignition coil, give the heads a ground!
If you have an cooked an ignition coil, rest assured the ONLY way to smoke a coil is insufficient ground to the head(s)/spark plugs.

Every one of the, "When I put on the brakes or turn signals, strange things happen" posts are lack of ground.

Poor Grounds will even cause your vehicle to rust/corrode, it's called 'Electrolysis'...
And Electrolysis is responsible for lots of light socket problems, corroded connectors, failed switching, etc.

So do yourself a favor and when you are working on something and have the harness apart anyway, ADD DEDICATED GROUNDS!

When you are changing the battery cables,
DO NOT buy those 'China' cheap ones from the discount stores!

Buy 4 Ga. or larger welding cable, use solid copper, Crimp on terminals,
CRIMP, THEN SOLDER with silver bearing solder,
Then heat shrink the connections. Heat shrink is cheap, easy to use, and comes in colors so you can color code your connections to make things easier next time!

thank you to jeephammer and many others for their contribution on this.

#2 User is offline   WRider 

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Posted 28 November 2008 - 12:51 AM

This post is worth reading...
Important Vehicle Grounding pointers are well addressed...
Found this 2 Cool Jeep Parts Sites Mobile Electronics and Off Road Products

#3 User is offline   coonbuster 

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Posted 01 December 2008 - 05:38 PM

That is one clean engine compartment!
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#4 User is offline   logandzwon 

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Posted 29 December 2008 - 12:29 PM

Excellent post!
Black 04 TJ Rubi, Snorkel, winch, lift - R.I.P.
Currently I just have a bunch of parts I'm trying to make into a Jeep.

#5 User is offline   Jim B 

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Posted 31 December 2008 - 09:44 AM

Let me add a few things to all of this as I just went through a similar situation with the Willys.

Terminal corrosion is not always visible. Old cables look just fine, but after stripping them of the insulation, they have a fair amount of green corrosion through out them. Often use welding cables for battery cables, it gives A LOT less resistance.

With a multimeter check the resistance between the lead and battery terminal then the cable/s resistance from the terminal to its mounting on the starter and or chassis. Then check from the grounded terminal direct to chassis.

Check your grounds the same way between the lead and where it is supposed to make good contact. Total time 10 minutes. Just like a system tune up! A cup of carb soda and water (poured over) is great to clean things up including terminals and battery tray, if you need.

You can always measure the voltage drop between the battery terminal and the starter case. Shouldn't be more than a volt, this goes for any ground connection you check. A little bit of grease on those shiny connections will keep them conducting for a long time, grease up every connection you clean so it won't corrode later.

Most important... you must be under load when checking all your ground connections. Ignition on and cranking, disconnect the coil so it does not start.

Often use welding cables for battery cables, it gives ALOT less resistance. Old cables look just fine, but after stripping them of the insulation, they have a fair amount of green corrosion through out them.

Below is a simple to follow URL link on Voltage Drop Testing which also explains it a bit further.
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#6 User is offline   Rollbar 

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Posted 31 December 2008 - 11:29 AM

P.S. Once the corrosion starts in the cables (in the sheath) it is hard to get out even w/ a cleaning agent (i.e. baking soda/coke). If it is that bad I suggest replacing the cables due to the strands being weak, loss of diameter from the corrosion (in-hibet current flow) & even some broken in the sheath when U bend them on inspection etc.
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#7 User is offline   Wildbill 

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Posted 01 January 2009 - 05:12 AM

Excellent post there Rollbar........ and it had pics too!!!!! JimB makes a VERY GOOD point about the cables as well, I was a victim of the internal corrosion on my 92 YJ and it drove me crazy until I discovered it. The Jeep would start one time, then the very next time if the cable got moved slightly and caused the connection to gap then it was a no go. :lol:

Oh and by the way........HAPPY NEW YEAR
Yale H.
Port Charlotte, FL


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2" BL, 4" R/C Susp. Lift...plus a couple extra stock leafs
Aussie Lockers Frt & Rear
33 x 12.50 Dunlop Mud Rovers
2004 Liberty Sport 3.7L 4X4
stock for now!!!

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