3g alternator....

1stanger1 said:

out of the "D" plug there is 3 wires....hook the white/black wire the the single plug on the alternator the yellow/white wire gets hooked to the stud on the back of the alt. and the green/red wire gets hooked to a switche 12v source then from the stud on the back of the alt with a 4ga it goes to the battery

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To perhaps clarify, the regulator plug is left alone (just unplug it from the 2G and plug it into the 3G).

So easy a cave man could do it! One of the best mods I made to my Mustang! With lights on, stereo w/ amp going, and Flexalite Extreme Puller fan running, all with underdrive pullys, hardly even moves volt gauge!

1stanger1 said:

but see here is where people just dont understand...i cant go by all the diagrams and all the stickes for this....if you think about it...my car is a 1999 a jammed in this 302 and fuel injected it...which was not hard but it wasnt easy either...so the motor had to be be hard wired to the car...no i didnt go to painless and get a $500 harness...

i like the way i have it hooked up. now with all my extensive expierience in doing this swap..i have done it 3 times with a 302 and this car even had a motor from a mark VIII in it. so i know almost every wire color on all the harneses and almost what every pin is for on 99% of computers on the 4.6 v8's and the 5.0 v8's from 1986 to 1999

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Yes, and I addressed what each wire does on your other thread. I guess I don't know why you have multiple alternator threads.

It was worth noting that the regulator wiring orientation/function did not change on a 2G vs a 3G (since you were apparently reading and postulating). Since you thought the stator wire was grounded (your other thread), it further seemed like clarification was needed.

This is what I posted on the other thread:

You might note letters on your regulator.

A receives circuit protection (if not reusing the stock wire and its fusible link) and goes to the battery.

I goes through an idiot light or through a 500 Ohm resistor (your call with your custom application) and to a source that's hot during cranking and running.

S goes to the lone port on the side of the 3G alternator. Do NOT ground this wire.

I would not use the blk/or wires at all. Pull the sense wire (labeled A at the regulator) out of the harness if you are not reusing the rectifier harness or you could use your own wire and circuit protection (going from A to the battery).

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Other than 94-95 mustangs does anyone have a list of other junkyard cars that would be a doner for the 3g alt upgrade????

rclifton said:

Other than 94-95 mustangs does anyone have a list of other junkyard cars that would be a doner for the 3g alt upgrade????

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You might find a list by Jrichker (IIRC) on some older threads.

I pulled mine from a contour. Said 130a on the factory label.

94-96 Mustang 3.8 V-6
94-95 Mustang 5.0
94-96 Thunderbird 3.8 V-6 (non SC)
95-96 Windstar 3.0 V-6 (most are 3.8's)
93-96 E/F series Trucks/Vans 4.9 L6*
96 Sable 3.0 V-6
94-96 Cougar 3.8 V-6
GOOGLE

I pulled mine out a Mercury minivan... the orientation of the connections was different, but it still went right in.

I did the conversion with a store bought alternator and originally wired up the heavy power and ground leads myself, but since ordered a PA Perf pre-made harness w/fuse.....problem is, ever since hooking up new wire I get the Alt red light in cluster comming on and off intermittently. anyone have any ideas whats going on? the old wire I had made kept getting hot right up to the fuse but never blew it.

Alternator troubleshooting for 86-93 5.0 Mustangs:

Never, never disconnect an alternator from the battery with the engine running. The resulting voltage spike can damage the car's electronics including the alternator.


Revised 15 April 2012 to add simple check for regulator failure in Engine off ignition on, battery fully charged section, item 2.

Red color text applies to cars with a 3G alternator.

Do all of these tests in sequence. Do not skip around. The results of each test depend on the results of the previous tests for correct interpretation.

Simple first step: Remove the alternator and take it to your local auto parts store. They can bench test it for free.

Use a safety pin to pierce and probe the insulated connectors from the rear when doing tests with the connector plugged into its' mating connector.

Engine off, ignition off, battery fully charged.
1.) Look for 12 volts at the alternator output. No 12 volts and the dark green fuse link between the orange/black wires and the battery side of the starter solenoid has open circuited.
3G alternator: Look for 12 volts at the stud on the back of the alternator where the 4 gauge power feed wire is bolted.
No voltage and the fuse for the 4 gauge power feed wire is open or there are some loose connections.
2.) Look for 12 volts on the yellow/white wire that is the power feed to the regulator. No 12 volts, and the fuse link for the yellow/white wire has open circuited.

Engine off, ignition on, battery fully charged:
1.) Alternator warning light should glow. No glow, bulb has burned out or there is a break in the wiring between the regulator plug and the dash. The warning light supplies an exciter voltage that tells the regulator to turn on. There is a 500 ohm resistor in parallel with the warning light so that if the bulb burns out, the regulator still gets the exciter voltage.
Disconnect the D connector with the 3 wires (yellow/white, white/black and green/red) from the voltage regulator.
Measure the voltage on the Lt green/red wire. It should be 12 volts. No 12 volts and the wire is broken, or the 500 ohm resistor and dash indicator lamp are bad. If the 12 volts is missing, replace the warning lamp. If after replacing the warning lamp, the test fails again, the wiring between the warning lamp and the alternator is faulty. The warning lamp circuit is part of the instrument panel and contains some connectors that may cause problems.

2.) Reconnect the D plug to the alternator
Probe the green/red wire from the rear of the connector and use the battery negative post as a ground. You should see 2.4-2.6 volts. No voltage and the previous tests passed, you have a failed voltage regulator. This is an actual measurement taken from a car with a working electrical system. If you see full or almost full12 volts, the regulator has failed.

Engine on, Ignition on, battery fully charged:
Probe the green/red wire from the rear of the connector and use the battery negative post as a ground. You should see battery voltage minus .25 to 1.0 volt. If the battery measured across the battery is 15.25 volts, you should see 14.50 volts

Familiarize yourself with the following application note from Fluke: See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help for help troubleshooting voltage drops across connections and components. .


You will need to do some voltage drop testing of several of the wires.

Start looking for these things:
1.) Bad diode(s) in the alternator - one or more diodes have open circuited and are causing the voltage to drop off as load increases. Remove the alternator and bench test it to confirm or deny this as being the problem.

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. Do the voltage drop test as shown in the Fluke tech note link. Measure the voltage drop between the alternator frame and the battery negative post. Watch for an increase in drop as the load increases. Use the Fluke voltage drop figures as guidelines for your decisions.

3.) Bad regulator that does not increase field current as load increases. Remove the alternator and bench test it to confirm or deny this as being the problem.

4.) Bad sense wire - open circuit in sense wiring or high resistance. The yellow/white wire is the voltage sense and power for the field. There is a fuse link embedded in the wiring where it connects to the black/orange wiring that can open up and cause problems. Disconnect the battery negative cable from the battery: this will keep you from making sparks when you do the next step. Then disconnect the yellow/white wire at the alternator and the green fuse link at the starter solenoid/starter relay. Measure the resistance between the alternator end of the yellow/white wire and the green fuse link: you should see less than 1 ohm. Reconnect all the wires when you have completed this step.

5.) Bad power feed wiring from the alternator. Use caution in the next step, since you will need to do it with everything powered up and the engine running. You are going to do the Fluke voltage drop tests on the power feed wiring, fuse links and associated parts. Connect one DMM lead to the battery side of the starter solenoid/starter relay. Carefully probe the backside of the black/orange wire connector where it plugs into the alternator. With the engine off, you should see very little voltage. Start the engine and increase the load on the electrical system. Watch for an increase in drop as the load increases. Use the Fluke voltage drop figures as guidelines for your decisions.




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

Alternator wiring circuit
Notice the green wire connects to a switched power source. The circuit contains a 500 ohm resistor in series between the switched power and the alternator. Connecting it to switched power keeps the regulator from drawing current when the engine is not running. The resistor limits the current flowing through the wire so that a fuse isn't needed if the wire shorts to ground.

Also notice the sense wire connects to the starter solenoid and it is fused. It connects to the starter solenoid so that it can "sense" the voltage drop across the output wiring from the alternator.

Replacement parts:
14 gauge fuse link for stock alternator.

Bussman BP/FL14 Fusible link
AutoZone

Dorman - Conduct-Tite 14 Gauge Fusible Link Wire Part No. 85620
Advance auto parts #85620
Pep Boys - SKU #8637594