boost21

Alright guys, The previous owner installed a bosch alternator and it is being replaced with a duralast gold one. The bosch wired up using only one of the two alternator plugs and the white wire for the voltage regulator. Now the duralast one requires both plugs, but the one that the voltage reg has been cut. I know they sell replacement plugs but I am not sure what the other two wires do on that harness. The car has msd ignition, so I don't want to screw something up. Does anyone know what that plug's wires do and if i can just wire them back up?

heres the two alternators....


Then the wire missing plug/other one(white wire and 2 black with red/orange stripe)

And a link to the plug I think I need to get.
http://www.partsamerica.com/ProductD...e=1265&PTSet=A

Also the original one has a spot to ground the case on it, is that one threaded opening on the back where the new one gets grounded?

Thanks any input will be appreciated.

mattdel

the two thick blacks are the wires that the actual charging is done through. on a 3g alternator conversion, those would hook to the terminal sticking out. i dont see a terminal coming from the new alt you have, so i can only assume it wont work.
get yourself a 3g alt from a tbird or 94-95 stang, v6 or v8, and follow the conversion diagrams shown in the tech articles.

boost21

ok, that has me thinking, The alternator that is on the car right now might not be charging due to those wires not being connected? the car stays around 12.5 volts while running and over the past week they havent really dropped, even with driving the car around the area. How is the alternator that is in there able to work without using both plugs?

heres a coupler more pictures of the old/current one and how its connected. I dont understand how it can work without needing those two black/orange wires, just the regulator. From the bolt is a ground, the small white wire i believe is the voltage regulator and the one plug is the other stock plug. Its model number is bosch 20205

ewgoetz

you need to do one of 2 things.
1. go to a junk yard and get a harness from a mustang from the same year as yours.
2. go back to the parts store you got that new alternator and tell them you got it for the worng year and like to trade it out for a 94 stang.

mattdel

yah if those wires aren't connected then you aren't getting voltage to the battery.
reinstall the old alt, and probe the back terminal with a volt meter.

boost21

The way that the old one(one thats on the car and came with it) is the bosch that is not using the two black wires. There is no spot for where the 2nd plug would go, but who had the car before me took the white wire from that harness and plugged it into the alternators voltage regulator? The duralast one I would assume would be more of a stock "plug in and play" alternator, but that plug was cut off. If those two wires/plug is what feeds the battery, I don't have any idea how the existing bosch alternator is or could do anything. Maby I'll just get the plug and wire it up and hope that nothing shorts/surges. I hate not knowing why something was done, especially with electrical things.

mattdel

they had it correct, that white does go to the regulator
the only thing stopping you from correcting this issue is those two blacks. they need to go to the post.

boost21

What post are you talking about? There are no more available plugs or connections on the current alternator (not one that utilizes both plugs) There is a 2nd ground on the back, or at least thats where it is wired to.

Thanks for the help so far, I just want to get this situation corrected.

mattdel

put the bosch back in, reconnect it all like it was, and take those two thick black wires, strip the ends and crimp an eye hole connector on them, and put them on the screw-on post on the back

boost21

do those just go straight to the battery? If so there is a 4 gauge wire that I would assume was added from that post to the neg on the battery as well as a second one that goes from the mounting bolt to the battery. If thats the correct wiring the voltage regulator must be shot because I would of thought that by now the battery would be completely dead if the alternator wasn't doing anything.