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Thread: 3g install **go directly to post 50 for drawing

  1. #11
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    Is doing the yellow wire like above recommended?

    I'm getting a huge overcharging state with my alternator, so I got it replaced and the replacement overcharges exactly the same. The voltage sensing wire reads the same voltage as the output (up to 15.1v(!), with the minimum around 14.6 unless all accessories are on, electric fan, at idle) so I'm assuming I need to ditch NAPA's alternators (lifetime warranty/replacement) for a good PA Performance one. Ignition on wire is a little lower, but not much. I double-checked the wiring and its wired up right (both by color and pin/wire testing with multimeter), but why does it seem like perhaps its regulating on the ignition wire?

  2. #12
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    The yellow wire should be connected directly to battery voltage, and that BAT terminal is the closest place to get it. Ford regulators switch on the ground side, and that yellow wire provides the positive to the field. It has nothing to do with sensing - that's what the white/black wire does.

    Are you sure it's overcharging? 14.6-15.1 is a bit high, but not completely out of the question, especially if you've got a dirty connection somewhere (corroded battery terminal, f'rinstance), or a weak battery (if the battery is struggling to take a charge the alt will put out more power).

    It is highly possible your multimeter is reading high - I've got one that shows 17 volts on my 13.8 volt regulated power supply (I've checked it with other meters and it shows 13.8 volts)

    And, of course, it's highly possible that your NAPA alternators were both crap. They use very cheap regulators, and multiple failures is not uncommon (just ask Eric)
    2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

    1988 5.0 Thunderbird SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

  3. #13
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    For the record, here's the factory wiring diagram for a 3G as installed in a '95 Mustang. The diagrams Scott and I posted above are essentially the same thing, but much easier to read:
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    2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

    1988 5.0 Thunderbird SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

  4. #14
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    multiple failures is not uncommon (just ask Eric)
    LOL Don't get me started. Between crap alternators and crap Optima batteries, I don't know whose head to start bashing in first...

    Yeah, I can post this stuff on the site. Thanks for the effort guys!

  5. #15
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    My multimeter's accurate, as is the digital one I added to the dash that got me seeing these numbers (Minus the voltage loss I get on the ground wire to the dash-mounted one, need to run a new ground - the wires read ~0.2v less than at the battery). No resistance between my alternator and battery (0 gauge ran), with very little from alternator out to yellow wire (will have to take a measurement again, but it was next to nothing). As far as I know, its either a crappy regulator or a bad battery, and both have been replaced with no improvement. Wonder if someone would buy my "lifetime NAPA" alternator w/receipt(s) from me for like $150 on craigslist Went for $250 or so, worth 1/10 that at idle output.

    Oh, and I'm assuming a PA Performance one won't bog down the motor as much either. The NAPA guy was surprised when the "bad" alternator kept killing his machine, so he called in a replacement. The new one barely ran, pulling 10+hp from it at full output (143A or so). The new one seems to have less output at idle then the old (voltage dips more frequently) and at startup, for the first couple minutes, I get like 15.3v, before it drops to 14.8 for some time. Afterwards deciding whether it wants to give me more or less which seems to depend on whether I'm in stop/go driving (stays about the same or drops a little) or on the freeway (slowly climbs back up to 15v, old one also did this, reason I replaced it).
    Last edited by Seek; 04-30-2007 at 12:20 AM.

  6. #16
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    i was gonna reply in a rather detailed way but you seem to know what you doing as far as accounting for the voltage drop across your connections and compensating for that in your reading.

    you also said your battery was new and that is kinda funny as well.

    ill babble a little here and you reply,,,,,,,

    when you turn on your meter to dc/v, what does it say with the leads not touching?

    measure how much """"""AC"""""" ouput you have coming out of your alternator. take that reading times .707 and that might be your problem. residual AC due to a not so perfect world regulator might be slightly bubbling your battery and also causing a slight high charge.

    I had an alt once that had about 2v ac output at the exact time when it was running about 16vdc ouput at idle. Cooked the battery to say the least but it did take some time.

    im gonna venture to say that your getting too much residual AC ouput due to a diode make/brand/connection issue that is isolated to the suppier(s).

    I dont know how your getting it but some piece part is causing it.

    are you running an inverter for any ac outlets in your car? anytime there is a device in your car prducing AC (such as the head end of your alternator) or an inverter (dc-ac), there are always some form of diode responsible for this. If any one of the many go bad, you will get ac feedback.

    ever notice that big ass diode near the eec test connector? ask about what that things purpose is.
    IIRC,, there are a couple (maybe one) diode in the harness loom near the starter relay or alt ouput harness ect along the side with the battery. check that out cause i think i remember one being in that harness and if its shorted,, you know the deal.

    i hate things that are nearly broke but not exactly broke yet!!!!!! good luck.
    Last edited by jcassity; 04-30-2007 at 06:44 AM.

  7. #17
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    eric
    ill do i write up in my DIY link as well. You or someone else please check this step by step below and make sure I did not forget a critical step.
    Last edited by jcassity; 04-11-2009 at 01:14 AM.

  8. #18
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    Multimeter leads not touching = 1, touching = 00.2 (Actron CP7674, not sure why its reading 0.2 now, it was 0.0 last time I used it. I did leave it on overnight though, battery may be finally dying.). I don't use anything AC powered, adapters or such. I'll give the AC readout a try. Have a local supplier of PA Perf alts here in Beaverton, OR (Krazy Koncepts - they have a 9 second (997hp) Mustang) so likely to pick one up. The fact that NAPA had to "order" an "older" replacement alt from another store (only one in the area) because they couldn't replace it with the newer ones/manufacturer they had in stock (also 3G 130A) for some stupid reason is what makes me want to ditch them all together. I can only assume there's a reason for going with a new manufacturer, and I get stuck on the bad end of it all.

    The original alt is 2 years old, the replacement is a month old. I put it in and still had the same problems there in the parking lot but they had no way of getting another replacement for me that day so I figured I'd drive it away and try dealing with another location that may be a bit more customer service oriented. It was funny, they tested it in the car and "everything checked out fine". I pulled it out and threw it on their machine. this is when they agreed to replace it. The guy testing it on the car didn't know anything other than ~14.5v (which it was doing as the car had been running for 15 minutes, giving it time to drop down in voltage before it would begin to rise back up again over the next couple hours). All but one of their employees were clueless.

    Of course, the PAPerf will probably put out twice the amperage at idle than the NAPA one...electric fan on DCControl comes on at idle and my voltage will start to drop to 13v, along with all lights dimming inside and out. Old one only did this with all accessories on, not only the fan.

  9. #19
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    Ummmm...I'm getting ~33.5v AC? That doesn't seem too right. I can probe an actual 24v AC wall adapter and get 24v AC though...also works near perfect for setting amplifier gains. Wall outlet gives me 119.6v.

  10. #20
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    im wondering if your fan isnt spiking the regulator. the sudden demand for current might be the deal.

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