Tips on getting a solid/consistent good charge?

A single 4 gauge wire should be sufficent.

The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. 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.

A voltmeter is handy if you are familiar with how to use it to find bad connections. Measure the voltage drop across a connection: more than .5 volts across a connection indicates a problem.
See http://www.fluke.com/application_notes/automotive/circuit.asp?AGID=1&SID=103 for help

I'd like to know, as well, being that my battery was relocated to the trunk before I purchased the 'Stang. I've got redundant grounds running off the negative post to two spots (body inside of trunk and quad shock mount), and I've cleaned up both ends of that funky braided stainless ground off the above-mentioned head-to-firewall connection, but I have no idea where the original negative cable grounded when it was up front.

Also been recommended to clean/upgrade the ground wire for the ECM, but I've not yet figured out where that particular ground is located (passenger-side kickpanel where the 'puter is, itself?). Won't help with charging, per se, but not a bad idea, while you're already dealing with ground wires and the like...

5spd GT said:

Thanks Joe

Now I'm wiring retartded so what is a battery pigtail and where would a good place to mount this wire be? Can I just get any old 4g wire from an electronic store or what?

I remember a ground from the back of the head to my firewall...is that what your talking about?

Click to expand...

The negative battery wire has one big wire that everyone knows about, it grounds to the engine block. That is the power ground for the starter.

There are two smaller 10 gauge wires that are part of negative battery wire. One is the computer power ground that has a black cylinderical disconnect. It connects to a 10 or 12 gauge black/green wire that runs directly to the computer. The other wire is the body ground for the battery. That is where to bolt the 4 gauge power ground for the 3G alternator. The other end of the 4 gauge wire bolts to the engine block.

The ground on the back of the head is the secondary power ground that I was talking about.

The 4 gauge wire is available at the auto parts store with the lugs already crimped on it. I used a 4 gauge solenoid to starter wire. Use a piece to string to check the cable routing and length.

Subscribing

The computer ground is behind the kickpanel IIRC.

jason

Darkwriter77 said:

I'd like to know, as well, being that my battery was relocated to the trunk before I purchased the 'Stang. I've got redundant grounds running off the negative post to two spots (body inside of trunk and quad shock mount), and I've cleaned up both ends of that funky braided stainless ground off the above-mentioned head-to-firewall connection, but I have no idea where the original negative cable grounded when it was up front.

Also been recommended to clean/upgrade the ground wire for the ECM, but I've not yet figured out where that particular ground is located (passenger-side kickpanel where the 'puter is, itself?). Won't help with charging, per se, but not a bad idea, while you're already dealing with ground wires and the like...

Click to expand...

Rear mounted battery ground wiring. Follow this plan and you will have zero ground problems.

One 1 gauge or 1/0 gauge wire from battery negative post to a clean shiny spot on the chassis near the battery. Use a 5/16” bolt and bolt it down to make the rear ground. Use a 1 gauge or 1/0 gauge wire from the rear ground bolt to a clean shiny spot on the block.

One 4 gauge wire from the block where you connected the battery ground wire to the chassis ground where the battery was mounted up front. Use a 5/16” bolt and bolt down the 4 gauge engine to chassis ground, make sure that it the metal around the bolt is clean & shiny. This is the alternator power ground.

Crimp or even better, solder the lugs on the all the wire. The local auto stereo shop will have them if the auto parts store doesn't. Use some heat shrink tubing to cover the lugs and make things look nice.

Computer power ground
The computer has a black/green dedicated power ground wire with a cylindrical quick connect (about 2 ½”long by 1” diameter. It comes out of the wiring harness near the ignition coil & starter solenoid (or relay). Be sure to bolt it to the chassis ground in the same place as you bolted the alternator power ground. This is an absolute don’t overlook it item for EFI cars

Your alternator ought to handle your electrical accessories (as described) just fine -- as others are suggesting, I'd check for insufficient grounds.