Swap, Alternator won't excite.

[steevz]

Okay, so I'm just in the completion stages of my B3 Wagon AAZ swap. She's running good now, but the alternator won't excite.

It's a Bosch alternator but it has the B+ for the power cable and then a 2 prong plug. The car has 1 blue wire for exciting the alternator. So, I butt connected the blue wire to both wires on the two prong plug with no success.

Does anyone know how I can get this alternator to turn on?

[8v-of-fury]

It should still only have one wire to excite. My 98 TDI swap still only needed one wire to excite. The other wire in that two prong plug is the W output, and does not need to be hooked up. I do believe it has a voltage come out, so you may have frigged something up?

[R.O.R-2.0]

It should still only have one wire to excite. My 98 TDI swap still only needed one wire to excite. The other wire in that two prong plug is the W output, and does not need to be hooked up. I do believe it has a voltage come out, so you may have frigged something up?

that would be my guess..

the alternator states witch one is D+, and witch is W..

it still works just like a regular bosch alt..

[8v-of-fury]

The backside of the alt says which of the two wires is D+ for sure, that is what you need to hook your blue wire up to.

[steevz]

Bah.. hope nothing is buggered up. I didn't see any markings on the alternator.. which is why I asked.. I'll check closer tomorrow.

[hillfolk'r]

yea look closer for that D+....
not like it helps,but the way the" idiot light works is:
one side of the light has b+ on it,and the other side going to the alt is" grounded" when the alt is not working..when its operating,theres ;+ on the" grounded" side and voila,the light goes out.
gotta have a ground and power for a circuit..put power to both sided of a light and it doesnt work....so knowing that you could" cheat" and temporarily remove the orig blue wire.....
get a lamp. ..hook one end to the batt,hook other to d+....start the car and check at the battery for charge output with a meter
oh,i was assuming you were leaving the orig b+charge lead hooked to the alt....with a meter u should see battery power there even with the car off,its always" hot"
doin what i described will eliminate the cars exiter wiring temporarily to determine if the alt is bad or not

[bbob203]

where did you get the swap motor?

[EcoTX]

Did you try giving it a good rev? 

Most of our diesel VW's need a good rev to excite the alternator for some reason... just one of those VW things I guess.

[CrazyAndy]

Did you try giving it a good rev? 

Most of our diesel VW's need a good rev to excite the alternator for some reason... just one of those VW things I guess.

This.  I wish I could explain why.  I'm a tech and cant understand why.

Wait, is it a V-belt or Serp setup?

[steevz]

Okay, going to go check it in a few minutes.

When it is unplugged the light is out.. is this normal?

Did you try giving it a good rev? 

Most of our diesel VW's need a good rev to excite the alternator for some reason... just one of those VW things I guess.

This.  I wish I could explain why.  I'm a tech and cant understand why.

Wait, is it a V-belt or Serp setup?

I tried revving it to excite.. know all about that. It's serpentine setup.

where did you get the swap motor?

I live in BC, Canada.. they're everywhere.

Paid $600CAD for an entire 94 Golf AAZ. Was from out East so the body had too much rust. Engine was in good shape and put my 02A tranny on it.. which I need to figure out how to adjust.

yea look closer for that D+....
not like it helps,but the way the" idiot light works is:
one side of the light has b+ on it,and the other side going to the alt is" grounded" when the alt is not working..when its operating,theres ;+ on the" grounded" side and voila,the light goes out.
gotta have a ground and power for a circuit..put power to both sided of a light and it doesnt work....so knowing that you could" cheat" and temporarily remove the orig blue wire.....
get a lamp. ..hook one end to the batt,hook other to d+....start the car and check at the battery for charge output with a meter
oh,i was assuming you were leaving the orig b+charge lead hooked to the alt....with a meter u should see battery power there even with the car off,its always" hot"
doin what i described will eliminate the cars exiter wiring temporarily to determine if the alt is bad or not

Thanks, will have a closer look.

So if I buggered with the W terminal going to the light I can just have power going to the D+ and it will work, correct? What if I just put a jumper from the W to the D+ for the time being? Haha.. probably not..

[steevz]

I found the D+ but I fear maybe I blew the diode when the W was hooked up too. Anyone know where it is located so I can swap it out from the other car?

[hillfolk'r]

yea lamp out when unplugged,normal.....if ya ground it,it should come on....
from my gen knowledge, i suspect the alt doesnt excite until the residual voltage comes up enough to get the volt regulator workin,it probably needs a certain amount of" juice" to turn on and put out.....even a generator that has" no output",it still has voltage if the windings and whatnot are ok....i get em all the time,no output,but if i read it with a meter it may be like 2-5-8 volts(now im talkin ac power same deal)..yes its not 120vac,but its telling me my residual voltage is there...i probably got a fried regulator or capacitor...


yes if u try a temporary bulb like i said itll work for testing
i tried to quote ya but there was too much to remove

an alternator is a generator with diodes to make it dc power....
one of my dreams in my shop now is to have the old timer there teach me how to rewind my alternator for 120vac output.granted it may only be 700-1000 watts but it would be cool

[745 turbogreasel]

from my gen knowledge, i suspect the alt doesnt excite until the residual voltage comes up enough to get the volt regulator workin,
yes if u try a temporary bulb like i said itll work for testing

In my experience, the rev thing gets worse as the pill with the brushes wears down, till eventually you can't rev high enough to initiate charge.
On some cars, changing the resistance of that bulb affects charging voltage.

an alternator is a generator with diodes to make it dc power....
one of my dreams in my shop now is to have the old timer there teach me how to rewind my alternator for 120vac output.granted it may only be 700-1000 watts but it would be cool
My house in Big Sur  had a Caddillac alternator wired like that for winter power. Belt driven by a 1887 cast Pelton water turbine.  You open the valve (~250 vertical feet 2.5" pipe), and the volt gauge rises, stop at 110-120.  Voltage would drop if you ran something big or a bunch of lights, so you would have to open it a little wider.  Ducks loved the pond.
Similar unit here http://www.oldpelton.net/pel12page.html  //threadjack.

[hillfolk'r]

yea thats frickin cool as fans
hey all ya gotta do to is throw a hz or frequency meters on that bad boy
make sure you are close to 60hz.
hz is just engine speed on a gen anyways...my lil kohler has a 4 pole rotor so that gives 60hz @ 1800rpm engine speed
the little peashooters have 2 poles, so they run 3600 for 60hz
id use my dvom to set it up on a car..
for the old timers get an analog  clock and a stopwatch lol
if its runnin 62hz lets say,then the clock will gain 2 seconds a minute

hey didja play more with the alternator , OP?

[steevz]

I just got off a 15 hour day at work. So I'm going to play with it tomorrow.

Going out to look at it now. Will update.