Neg. Cable Route With 5.0

I think that the ground for the EEC is incorporated into the negative cable.


I wouldn't wing it...
http://www.latemodelrestoration.com/item/WC8699/83-93-Mustang-Negative-Battery-Cable

Grounds are important to any electrical system, and especially to computer controlled engines. In an automobile, the ground is the return path for power to get back to the alternator and battery.

1.) The main power ground is from engine block to battery: it is the power ground for the starter & alternator.


2.) 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. The clue to a bad ground here is that the temp gauge goes up as you add electrical load such as heater, lights and A/C.

Any car that has a 3G or high output current alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects. The 3G has a 130 amp capacity, so you wire the power side with 4 gauge wire. It stands to reason that the ground side handles just as much current, so it needs to be 4 gauge too.

The picture shows the common ground point for the battery , computer, & extra 3G alternator ground wire as described above in paragraph 2. A screwdriver points to the bolt that is the common ground point.

The battery common ground is a 10 gauge pigtail with the computer ground attached to it.
Picture courtesy timewarped1972


Correct negative battery ground cable.

jrichker said:

2.) 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. The clue to a bad ground here is that the temp gauge goes up as you add electrical load such as heater, lights and A/C.

Click to expand...

Is that meaning a slight change, major change or ANY movement at all??

Grabbin' Asphalt said:

Is that meaning a slight change, major change or ANY movement at all??

Click to expand...

Usually it's a significant change. Use the voltage drop tests as described below if you have any doubts.

See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help for help troubleshooting voltage drops across connections and components. Be sure to have the maximum load on a circuit when testing voltage drops across connections. As current across a defective or weak connection, increases so does the voltage drop. A circuit or connection may check out good with no load or minimal load, but show up bad under maximum load conditions. .

Voltage drops should not exceed the following:
200 mV Wire or cable
300 mV Switch
100 mV Ground
0 mV to <50 mV Sensor Connections
0.0V bolt together connections