alternator driving me crazy.. what am I doing wrong?

this is a mustang 3g 160 amp alternator in my 460 setup. It worked in test before painting. I have had the alternator tested at Autozone, and it is ok. I have also used my 75amp original alt with the same results.. no output.

this is how I am wired, without the actual lamp.. on the excite line.
This is an Ezwire harness, so should provide the right resistance..
but... measured across the alt-excite and the battery + there is no measurable resistance (200ohm setting reads 0).

I do not have gauges installed yet.

in test, I wired the excite wire directly to the run side of the ignition switch

Ezwire says not to worry about where the excite wire goes in the harness.

Sam

 

Is your fuse blown? Usually that would be a fusible link.

 

no, I have checked that. I am also measuring output at the back of the alternator.

I do have a fusible link in the 'alt power' circuit (yellow/blk wire), but have clipped the wire and wired directly to the alt output as EZwire said to do.
I also have a 200amp fuse in the 4ga lead out to the starter solenoid, where it connects with the battery lead. Neither the fusible link, nor the fuse are blown.

for cleanliness I do have the alt-power and yellow/blk connected AT the starter solenoid, each has a fusible link.
Sam

 

So, both alternators test good on the bench at Autozone but they won't work on the truck?

From looking at the schematic the alternator is getting its 12V input on the Yellow/blk wire which is hooked directly to the Batt cable at the starter solenoid. OK, so far so good. The only thing you don't have is the idiot light (LG/R) wired in right? How about taking a 12V test light or any 12V bulb you might have laying about and wire it into the LG/R wire and see what happens. You could probably do a quick down and dirty jumper right at the alternator as a test.

One by one you'll get the bugs worked out
Bobby

 

sam,i know this maybe a dumb question but do you have the alt output wire connected to the batt cable side of the starter solenoid???????

 

yes, this is a GM style solenoid.. only two places to connect..

the start wire, and everything else.

so on the big, everything else lug I have

1. battery +
2. Alternator output (after master fuse)
3. EzWire 'alternator power' lead after fusible link
4. yellow/blk from alternator plug, after fusible link, (not switched)

the EzWire 'alternator excite' connects to the green/red wire on the alternator plug. (switched)

EzWire was unhappy with 4 above, demanding that it be connected directly to the alternator output lug, so I have it connected to their requirements temporarily.. (no change of course)..

Sam

 

Another dumb question but worth a shot, have you revved the motor up to energize the altenator? I know very little about electronics, but mine has to get over a certain RPM before it starts charging.

 

Good ground thru Alt brkt, Good Engine to frame and frame to B- grounds?
I always go for the easy stuff first........

 

yep, reved

and yep, used a jumper cable to insure ground direct from the battery ... all no change

Sam

 

you said a GM style solenoid on the starter? are you talking the standard ford 460 starter with the solenoid on it? these are not really like the GM solenoids as they still require the use of the standard Ford fender mount (don't know exactly how to name it) solenoid. the starter mounted solenoid is only hot when the main solenoid is energized. therefore the battery terminal and alt wire have to go to the battery side (not starter side) of the main solenoid.

of course if you have an aftermarket starter with gm style solenoid then above is not true.

Rgdsw
Mike

 

aftermarket, racing mini starter. GM style with complete solenoid on board. Summit® Protorque Starters: SUM-820048-M - summitracing.com

sam

 

Sam,

Cool starter. I take it it just has the large lug for the battery cable and a small terminal for the wire from the ignition switch? if so then you are should be good with putting the output and the yellow/blk wire from the alternator on the battery lug.

I'm a little confused on your description above. Where does #3. the EZ wire "alternator power" lead tie in? Is that the LG/R wire?

Bobby

 

hades thats the one area , and i don't care how many of you say it's simple , that i dont get the jist of . so whatever you do sam don't ask me i'd put you in touch with my freind bud whom i am gonna help with my rewire { if i or he ever get time away to do it !!!!!! } . mines got the gm alternator ran to the solenoid , battery side i think and he had to fix it as the po had it wired charging the whole system , listen to me and i'll have ya wired into the 220 outlet in your garage in no time !!!!!!!!!!!!!

 

there are three wires in the front harness from EZWire 'Alternator excite', 'Alternator Power', and 'Battery Power' that need attention

Battery Power says Solenoid
Alternator Power = Red
Alternator Excite = White

EZwire says, from direct phone call.

Alternator Power goes to output of alternator, main lug, AT the alternator, not the solenoid. the Alternator regulator 'A' terminal goes here too. Always on. (B+ in the diagram) I have mine wired at the solenoid main lug

Alternator Excite goes to the 'I' side of the regulator, this is ignition switched . (I in the diagram)

the I/S/A three wire is a molded connector on the ford alternator, and the S wire is also a molded plug back into the S terminal.

I tried the test light across the I line.. no change
I jumpered the test light to ground on one side, and to the circuit on the other, no change. (it lights on key on)

I shorted the test pin on the regulator, no change.

no change = 12volts on the meter,
Sam

 

I think if your LG/R wire is at the exact same voltage as the output, it is going to tell the alt that no power needs to be generated. It needs to see a difference between system voltage level and alternator level; it has no internal 12v reference. That's one reason there is a bulb in the circuit.