While looking/searching for information and support material for this topic, I found a great C & C tech article on the subject titled "How to Avoid the Top 10 Electrical SNAFU's", which I recommend you read...great information.
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The following ground system upgrade is recommended for either EFI or carbed setups. It ensures a solid ground circuit to prevent problems like:

1. Intermittent EFI problems.
2. Dimming of headlights and interior lights.
3. Erratic gauge readings (fuel, temperature, charging)
4. Alternator overload (bad ground causes alternator to max out)
5. Better starter performance (an upgraded ground circuit could be considered as a way of compensating for starter heat soaking symptoms).

I. Fine Stranded Battery Cables
Replace existent battery cables with high quality replacements, an upgrade to 0W or 2/0 gauge is recommended, and the use of fine stranded cables ensures great conductivity, durability and flexibility. Strand density is important...regular battery replacements have stranded copper wires in the tens, while fine stranded cables are in the thousands. They're more expensive, but worth the investment due to their low resistivity, flexibility and ruggedness to heat. The following pic shows what is referred to as strand density:



or look for a replacement cable that looks like this one....



II. "Ground Loop"
When you visualize a typical ground circuit, need to look at it, as an electrical loop. All electrical/electronics equipment are sensitive to noise, electrical variations (spikes/dead spots) and will affect either accuracy (gauges, sensor outputs, ECM), control quality (DC frequency voltage for actuators like IAC/Injectors/Solenoids), or the lifespan of the equipment in use (alternator, starter, ECM).
The connections that make up the "ground loop" are:

1. Battery Post-to-Engine
2. Engine-to-Frame
3. Frame-to-Battery Post (ends where it started)

III. Battery Post-to-Engine
As mentioned above, an upgrade to fine stranded battery cables is recommended, along with an upgrade to 1/0 or 2/0 gauge. Any contact point to the engine should be stripped of paint. AN engine block location is preferred, but the use of the cylinder heads and the timing cover is acceptable. An addition to ensure a permanent and reliable metal-to-metal contact, is the use of External Star Washers.....



These are recommended to be installed any place a ground wire is attached, they are available in the typical eyelet connector sizes...which takes us to the next ground connection....

IV. Engine-to-Frame
This is the most important ground connection for gauges, interior lights, exterior lights...proper operation. The OEM setup in our Mustangs is via a ground strap, usually located behind the RH cylinder head and attached to the firewall...



It is recommended that this strap, if it's still in place, be reconditioned or replaced by a new one, making sure the contact points are stripped from paint, and the use of the external star washers. It is also recommended to add a second ground strap at an alternate engine-to-ground location, as a reinforcement/redundant measure. This second strap takes more importance when a battery relocation to the trunk is made.

V. Frame-to-Battery Post
This is the last ground connection, and the one that completes the loop. This connection is usually found near the battery to the inner fender its contact takes importance, since it's usually shared or used, for the EEC ground....



A ground strap will do the job....remember to strip the paint for the contact area and the use of the external star washers. The 4G cable attached to the inner fenderwall, in the pic above, is another ground reinforcement connected to the engine block when a 3G+ alternator upgrade is done. You don't know how much money I've made thanks to that little EEC ground....thank you Ford!..

There....your ground system should be "bulletproof"....High compression engines, music equipment installations, the addition of performance electrical equipment like Electrical Crankcase Vacuum Pump, Electrical WP, 2-speed Radiator Fan, Dual Radiator Fans are not excuses to upgrade the grounds.....it's a requirement!...but most of the times........overlooked.

good post! a simple ground problem can wreak havoc
on your car and leave you guessing.
i had a neg batt. cable go bad and it wouldnt let my car
start and then fried my starter, so check those grounds folks

Another good post Joel!

Along with that, NEG cable when you relocate your battery. Finding a place to ground can be difficult.

Great info!!! I have had some problems with grounding in the past.
Solved many with your addvice!!!!
thanks again...

I have been usuing alot of these lately for grounds,They take place of ring connectors.They are avalible in 4ga and 0ga.Unlike rings that use 1 screw/bolt these use 2 to hold it in so it has ALMOST no chance of coming loose http://www.stingerelectronics.com has them and many other audio companies have them too.