2g to 3g upgrade?

[LtMercDaddy]

Ok I just scored me a 3g for free, just gotta go have it tested.. anyhows if it does test ok, ill be planning on installing it. I do have a couple of questions rather a installation method that I just want a second opinion on before i do it, so i dont fry my car as that would really suck. Anyhows, i understand that theres currently 2 plugs on the back of my factory 2g alteration a wide one and a fat squarish one, both of which have 3 wires coming out of each.... from what im understanding of previous posts is that the wide plug needs the plug cut of and cable lugs installed on the end of the fat black/orange wire and the other fat wire, those two wires get connected to the post bolt on the back of the new 3g alt.... since the old alt is a 65amp or whatever a 3rd fused heavy guage wire needs to be added from the post on the back of the 3g to eather the positive battery terminal or the positive side of the starter solenoid? Now the 3rd little wire which i believe is white gets the single wire plug put on it and plugs into the single input or (S) I believe on the 3g? And finally the other plug squarish round fat one just plugs right in?...... Need some clarification here... previous posts have been kinda confusing.... btw my 3g is from a 3.0 taurus i think.....

[Archangel]

Seems like you got it right - one of the plugs will fit right into the new alternator, the other ones gets the wires snipped off and the two fat ones get bolted to the new alternator's post, the thin one gets a spade connector and plugs in the side of the new alternator. The extra power wire from the alternator doesn't need to be bigger than 4awg, I use 6 awg and I'm happy with it.

[gadget73]

I'm actually not using the thick wires from the original 2g wiring harness at all. I completely removed them and I have only the heavy single 4 ga wire that runs through a breaker to the battery. I dumped them as part of my general wiring cleanup process.

[Archangel]

Thain, in that case I have a question for you - where do these wires go to when they leave the alternator? One defintely runs along the header panel all the way to the starter relay, what about the other though, couldn't trace it at all.

[gadget73]

All 3 run over to the starter relay. One is a battery sense wire, the other two are just fat wires. Mine join at a single fuse link right about at the battery. I cut the battery sense wire which is the thicker white wire coming from the voltage regulator, and jumped it directly to the terminal on the back of the alternator. Looks like this:


Green wire goes to the idiot light. The thin wire in the alternator harness is actually the low oil level light. I have no idea why they chose to incorporate the oil level light into the alternator plug while the alternator idiot light wire goes to a big electrical plug that does nothing else. Oddly, at least on my car, there is a jumper wire in the big connector the green wire goes to. If that connector is unplugged, the car won't run.

[LtMercDaddy]

Thats the only wire needed? the green one? damn. I guess after i get this alternator tested I do some experimentation with some wires (scary) BTW anyone know how i can get the amperage off this alt, called Autozone they say can only test voltage? would be nice to know the exact range of amperage before i go wiring and fusing....

[gadget73]

The tester at the Advance I go to sometimes can check current output. Your Autozone must either have a crappy tester, or they must not be able to operate it properly. Testing just voltage output is almost completely worthless on a charging system anyway. Unless its load tested, it could be putting out a perfect 14 volts at like 3 amps max current and you'd never know it.

And yeah, the green one is really all thats needed. I can't tell you with certainty what that circuit runs to since I don't have my manuals, but I do know my idiot light works properly, so I assume it must connect through the idiot light somehow. I had the 150 amp breaker pop once on me, and the idiot light came on instantly.

http://fordfuelinjection.com/?p=75

has a bit more info on the swap. Thier harness has the same jumper arrangement I'm using on my car, and to be honest thats where I got the idea. You can also fuse the thing instead of a breaker. Scott and I raided a 170 amp fuse off a newer Taurus's charging system for use on a project. The Taurii has a hot cable from alt to a fuse mounted right on the side of the under-hood power panel, and then it goes from fuse to the + terminal on the power panel. The battery sense wire connects to the fuse, not to the terminal right on the alternator, but the cable between alternator and fuse is like 14" or something. Its pretty short in any case. I used a breaker, which is like $30, mostly for the fact that if it pops for some reason, I can just reset it. If I were to have an oddly high current fuse fry on me for some reason in an out of the way location, I'd be pretty much SOL once the battery went too low to run the car.

[Archangel]

Thain, the way you have it set up now, how is the idiot light knowing the alternator has gone south? If the battery sensing wire is hooked up to the back terminal of the alternator as long as the alternator is running fine it should still read the battery as fine, even though the fuse has fried, am I correct? On the Taurus, the battery sense wire connects to the fuse, okay, on which side though - towards the battery (power distribution panel) or towards the alternator?

[gadget73]

I believe the sense wire on the Taurii connects to the fused side, so effectively its right to the output terminal on the alternator. On the stock 2g harness, the sense wire runs parallel to the two black wires all the way over to the fuse link at the starter relay, also tying in on the alternator side of the fuse link. As far as exactly what that green wire goes to, I have no clue, but my amp light does work. That wire goes to wherever it went in stock form. The battery sense line doesn't connect through the light either, so whatever the specifics of that circuit are, they are still working. I know it works because one time the breaker popped on me, and the idiot light came on. Thats how I knew it popped. I reset the breaker and the light went out. I'm suspecting it runs from switched +, through the light, and then to the alternator. I know some charging systems depend on that bulb being good to function. The one in my Beetle was that way. I was going nuts trying to fix the charging system in my 73 when I got it. I finally gave up and asked my uncle after replacing the generator, regulator, checking all the connections, and metering out the wiring. He chuckled and told me to replace the dash bulb. I never considered it but he was absolutely correct.