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Alternator Plug Wiring

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Old 01-26-2012, 08:14 PM   #1
brnc_bstr87
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Default Alternator Plug Wiring

Ok I've tried to some research but got nowhere... What I have is a 1987 Gt 5spd. I've been having some problems with the battery not charging so I took the alternator off to have it tested. While unplugging the alternator the plug on the side (I think the rectfier plug?) was found to be melted on the plug end and the wires came right out of the plug. I went to the parts store to get new plug but I'm not sure how to splice in new one since the old wires are just loose I don't have a plug to reference. Can anyone tell me what wires are spliced into old wires??? Any help would be most appreciated!! Thanks :-)

Edit: Here's some more info on my problem... There's 3 wires, there's only one small wire so that's no bug deal. The other 2 are the same size and color. Does it matter which one gets spliced to???
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Last edited by brnc_bstr87; 01-26-2012 at 08:23 PM. Reason: More info
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Old 01-26-2012, 08:39 PM   #2
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Sounds like you picked up a 3g alternator wiring plug(94+). The fox wiring harness had 2 wires if I remember correctly.... (upgraded to 3g like 4 years ago). The harness is wrong and you shouldn't try to rig it to work right.

You need to cut off your failed connection and take it to the parts store. If they can not find an exacy replacement then you need to search online for one or make it yourself..... or upgrade your alternator.
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Old 01-26-2012, 08:52 PM   #3
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No it's the other plug and it has the same number and sizes of wires. See the plug came completely off the wires so I don't know which wires on the new plug splice onto the old wires (except the one small one).
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Old 01-26-2012, 09:37 PM   #4
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Pictures please. If it is as simple as the plug wires falling out of the old connection then just someone didn't know how to install the conversion. I can upload pics of the proper wire connections tommorrow. I can't tonight.

It should have been spliced via wires unless you or the previous owner knows how to install connectors.
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Old 01-27-2012, 12:49 AM   #5
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I would just do the 3G alternator upgrade at this point. My 2g alternator just started on fire. so if the wires to the rectifier are melted, you may be going down the same path my 93 mustang just went down. I was lucky I caught it before it set something on fire. 2G is a p.o.s.!
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Old 01-27-2012, 08:16 AM   #6
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That's what I'm thinking I should do to but at this point I don't have the money to buy the 3g alternator :-(. The new plug was only $10 vs $70 but I should have the money within 2 months & will do it then. So correct me if I'm wrong, the 3g has only a one wire setup?
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Old 01-27-2012, 08:40 AM   #7
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It has two connectors, actually. Disregard my second post, I was confused and thought u had a 3g connection when i wrote it.

Refer to this for pictures, wiring diagrams, and other useful information.

http://oldfuelinjection.com/?p=63
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Old 01-27-2012, 01:37 PM   #8
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Yeah it's only a single wire to the rectifier and the same D shaped plug to the stator remains untouched and is reused. You should also add a 200 amp circuit breaker as well. If your local pick n pull has a ford taurus or 94-95 mustangs you could score a good 130 amp alternator from there.
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Old 01-27-2012, 03:40 PM   #9
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Thanks to all for the info! @ Tony71502: Yeah I was confused there too at first lol but your site helped a lot! I got it all wired in plugged up, charged battery last on charger to have a full charge. Started up just fine, ran 2-3 min I turned off then back on. Ran for 10 - 15 min this time but wouldn't start back up. Something is not allowing the battery to charge! So far I've replaced the alternator plug, ignition module on distributor, & new positive battery cable. Any suggestions???
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Old 01-28-2012, 11:42 AM   #10
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Okay here's an update from some research/work I've done since yesterday. I went ahead & bought a new regulator plug also. I'm contemplating taking the or/bl wires from the rectifier plug (first replaced plug) and running them to a new inline fuse & then to the positive side of the solenoid to bypass the original fuse in case it's blown. My question is this now haha, on the site that Tony so helpfully gave me :-), the 2g wiring diagram shows the 2 plugs sharing the yellow wire that comes out of the regualtor plug right before it goes into the same inline fuse that the rectifier plug uses. What do I do about the yellow wire??? I mean, I know it comes out of the other plug but since it goes into the same fuse that I'm bypassing do I need to include that to the new fuse also??? Here's a pic of the diagram. http://oldfuelinjection.com/public/a...ALT_wiring.gif

Also, what size fuse would I need for the new inline fuse
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Old 01-29-2012, 01:38 AM   #11
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The orange/black wires have fusible links. No need to run a fuse on them. If you upgrade you just need to run the bigger wire with a megafuse in addition to the stock black/orange wires.
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Old 01-30-2012, 11:39 AM   #12
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So do I splice the bl/or & yellow wires coming out of the plugs to the new upgraded wire? Thanks for your help :-)
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Old 01-30-2012, 12:02 PM   #13
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Can you take any pictures? The bl/or wires shouldn't be touched and should be bolted to the alternator post along with the new 4g power wire. The 4g power wire should run from solenoid to alternator with a mega-fuse somewhere in between.

Here we go.. this looks like how it should be set-up. This is how mine is. The two bl/or go to the post. The yellow is spliced to a new white plug which goes to the alternator along with the stock plug.

http://www.musclemustangfastfords.co.../photo_16.html

Read that whole article for more info.

I just dug up my photobucket picture. This is how it should be. Notice the stock connector has the new plug spliced in. And you can also see my bl/orange wires in the picture.

Click the image to open in full size.
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Old 01-30-2012, 01:55 PM   #14
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I believe I've got it figured out now. I'll wait till I get a 3g alternator hopefully this week or next & take some pics for you. Thanks again for your help! ~Q
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Old 03-12-2012, 12:00 PM   #15
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Ok I got a 3g alternator finally! Here's how I hooked it up... Battery cable wire (4 ga) from positive side on starter terminal to mega fuse (it's either a 175amp or 250amp). Ran another battery cable wire from that to the back of the alternator. On the alternator I took the plug that it keeps from the old system and ran the yellow wire to the same place as the battery cable, white wire to the rectifier? plug & the green wire to the old green wire for the key in run position. So the only wire that I'm using from the original system is the green ignition wire. Got that all installed, charged the battery & started 'er up. Ran good, battery gauge on dash reading higher than used to. Let it run idle in driveway for ummm maybe 15 - 30 min? Turned it off to try to start it & battery is dead again! I'm so frustrated & I'm not sure where to go from here. Does anyone have any suggestions??? How can I tell if something is drawing from the battery (but if the car is on it should be recharging itself???)? Do I test with a meter at alternator & battery? If so what do I touch to get a reading & what should I be getting? I know, I know lots of questions haha. Please help! Thanks ~Q
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Old 03-12-2012, 03:38 PM   #16
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If you're getting 14v at the battery you may have a bad battery. Get it tested.
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Old 03-13-2012, 09:57 PM   #17
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@ Boss Hotrod: I've already had the battery tested but thanks for the suggestion :-). Here's an update on what I have now... 3g alternator from '94 mustang w/ a regulator plug, post for power to battery, &, in place of the old rectifier plug, a single plug. From the regulator plug I wired the yellow to the post, green to old green wire for hot with key in on position, and the white wire to the single plug on the alternator. That leaves the white & yellow wire on the factory harness unused. The wires from the old rectifier plug were 2 black/orange wires & a white wire. I took the 2 black, orange wires and put them on the alternator post. Which leaves the white wire unused on the factory harness. From the positive on the starter solenoid I ran a 4 gauge to a 175 amp fuse & the other side of the fuse another 4 gauge wire to the post on the alternator. Charged the battery completely, went to hook the battery up, put the negative on but when I touch the positive to the battery the engine trys to crank! That's never happened before. Does this have something to do with the ignition coil (maybe a short?). I noticed the plug into the ignition coil is kinda old with the wires a little loose. Also, I need to know if I properly wired up the alternator??? I so appreciate everyone's help so far! ~Q

Edit: I fixed the cranking issue. Turns out I had the 4 gauge wire from the alternator on the negative side of the starter solenoid (yeah I know dumb me I was just concentrating on the other wiring I guess haha). Anywho, I still need to know if the other wires are wired properly. Thanks!
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Old 03-15-2012, 09:39 AM   #18
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Okay tried something new yesterday... On the regulator plug I wired the white back to original white, green to original green, & yellow to alternator post. The wires from the old rectifier plug I took the 2 or/bl wires & put them to the alternator post & the original white wire to the single D shaped plug on the alternator. That leaves just the factory yellow wire to the regulator unused. It seemed to fire up real good but once again after 10 min if wouldn't start back up. I did notice that the starter solenoid was pretty warm but I don't think it got warm while it was running. So maybe I have my wiring right now but it's not transferring to the battery??? Then again though the alternator doesn't actually start the car right? Any help would be awesome! ~Q

Another thought here... If the starter is bad and won't let the car restart once it's warm can that make it seem as if the battery is dead???
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Old 03-15-2012, 01:54 PM   #19
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Are you testing the battery after it fails to start? If you have no means to do that, let it sit for a couple hours and try starting it again. That ought to eliminate any question of the starter. If it starts right up after sitting, the starter might be bad.

When you try to start it after you turn it off, does it try to turn over slowly, or do you get a clicking sound, or do you hear nothing at all?

The battery is what provides the voltage to start the car, the alternator charges the battery and provides power while you are driving.
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Old 04-02-2012, 09:44 AM   #20
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Well.... Success!!! Finally got it running strong & dependable. I took the starter off & had it tested. It blew the auto parts testing fuses twice it was drawing so much amperage. I also replaced both battery cables & cleaned the grounds. I want to thank everyone for their help! You guys have been awesome :-). Now just to save up for a new transmission since the fifth gear is shot in mine. Does anyone have any ideas what might cause 5th gear to be out in a T5??? I'm not sure if I should find a solution & rebuild it or get another one either salvaged or refurbished w/ warranty??? Hope everyone had a great weekend! ~Q
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Old 04-02-2012, 09:44 AM
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