Something doesn't make sense about my electrical.

[Dbeck002]

2 months ago I complained about my alternators diode being fried. This alternator was brand new. I had all kinds of problems with the battery, also new.

The alternator was replaced and the problems are gone. But the old alternator was so good I sent it back to the company to be repaired, it has a warranty.

So in the meantime I'm running a stock replacement which can barely handle my electric radiator fan, but it was doing ok.

I get the other alternator back from the place and install it. The car starts but the voltmeter shows no charge. I thought this was the 'repaired' alternator.

I install my other alternator (stock one that is brand new) and it shows no charge!
So in a way this is good, I know that it's not the alternator that is damaged because if both alternators aren't charging than there is something wrong with my cables or ground. I checked my grounds though and they seem to be fine. What else can cause a brand new alternator to not show charge above 12volt?

 

[marine_2003]

You could have a bad connection, your voltage regulator could also be bad, make sure your belt is tight on the alternator or it will skip over the pulley. I have a one wire alternator on my mustang that doesnt charge the battery until the engine runs at 1000 rpm. You might have an alternator like that.

 

[HISSIN50]

Yeah, more info please. Marine 2003 is correct about what is needed to get a 'charge' out of self-exciting alternators, but we dont know what you have. Since the 2G does not work also, provide info on the wiring upgrade you did.

Did you remove the oem charging cable at the starter solenoid? It contains a wire for voltage regulation and is necessary.

Has the battery been load tested? A bad cell will keep the system from charging.

Good luck.

 

[Dbeck002]

The alternator that I used was a 3G alternator 150 amp. I installed it 5 months ago with my relocated battery. The cables are dual 2 gauge high strand and can handle the amps fine. The starter solenoid is new.

About a month ago I had a problem with my battery draining overnight. I towed it to the mechanic and he said that the alternator and battery are both fried. So I replaced them both and the problem was gone. The fried 3G was sent to texas to be repaired under warranty. I just got it back yesterday. Until then, the replacement stock 75 amp alternator has been holding out just fine. I know that the charge shows only when revving. Today when I replaced the stock with the freshly repaired 3G, the voltage was showing 12 even under revs. So, I put the stock alternator back in and THAT TOO was showing 12 under revs. All this and I didn't change a damn thing in the process. It's like outta nowhere. Both alternators are practically brand new, it can't be the alternators.

 

[Dbeck002]

bump

 

[jrichker]

Note: all voltage measurements use the chassis as the ground. When you make a voltage measurement, it is assumed that one voltmeter lead is connected to ground.

Notice the ignition switch in the lower RH corner of the diagram. It has a red/lt green wire that goes to the alternator warning light. It should have 12 volts when the ignition switch is in the run position. No 12 volts and the ignition switch is bad. This is the signal that tells the regulator to turn on and supply current to the alternator field windings.

Turn the ignition switch off & disconnect the small plug on the alternator. You will find 3 wires: white/black, yellow/white & lt green/red. The yellow/white wire should have 12 volts on it. No 12 volts and the fuse link shown in the diagram is open.

Next make sure the ignition switch is on and measure the voltage on the lt green/red wire. It should be 12 volts. No 12 volts and the wire is broken, or the 500 ohm resistor and dash indicator lamp is bad.

Turn the ignition switch off, and measure the resistance between the lt green wire and the red/lt green wire on the ignition switch. You should see 500 ohms or less. More than the 500 ohms indicates bad wiring or a bad connection.

Next disconnect the plug with the 2 black/orange wires and the white/black wire. Measure the resistance between the white/black wire on the big plug with the black/orange wires and the white/ black wire smaller plug with the lt green/red, yellow/white wires. It should be less than 1 ohm. More than that indicates bad wiring or bad connection in the white/black wire.

 

[Dbeck002]

Sweet info dude! Thanks, I will try this stuff tonight and tell you what I find.

 

[Dbeck002]

"Next make sure the ignition switch is on and measure the voltage on the lt green/red wire. It should be 12 volts. No 12 volts and the wire is broken, or the 500 ohm resistor and dash indicator lamp is bad. "



When you say ignition switch is ON. do you mean the car running, or Key On Engine off?

 

[04sleeper]

When you say ignition switch is ON. do you mean the car running, or Key On Engine off?

Key On Engine off.

Good Luck with your findings.

 

[Insane3D]

"Next make sure the ignition switch is on and measure the voltage on the lt green/red wire. It should be 12 volts. No 12 volts and the wire is broken, or the 500 ohm resistor and dash indicator lamp is bad. "



When you say ignition switch is ON. do you mean the car running, or Key On Engine off?

Ignition on, engine off. It's the lead for the voltmeter in the instrument cluster. If you have a problem there, it likely means the alternator is charging fine, but there is a problem with the dash voltage gauge or its lead. I may be wrong, but this might also signal a problem in the voltage regulator itself. I'll defer to jrichker on that though.

Good luck!

 

[Dbeck002]

Ah my friend how do I know the stock idiot gauge is still working?

I turn the key on and see the needle move to the second line, turn the lights on and the needle drops a tad, turn the fan on and it drops more.. it is reading voltage. when the car starts and i rev it the voltage is constant, as opposed to spiking with RPMs!! I will do what everyone suggested. Keep the ideas coming, old cars need to be fixed its just part of the game

 

[Euphoric306]

sounds like a bad volt. regulator

try replacing that - under 20 bucks and is very likely the problem

id try and use a DMM just to be sure there isnt a problem with factory gauges. they are very untrustworthy

i almost pulled my engine to replace a bad oil pump before we grounded the pressure sender and found my gauge wasnt calibrated right

 

[Dbeck002]

Ok im about to go do the diagnostic on the electrical.

But before i do i want you guys to know what i did before with the stock alternator cables.

I asked a little while ago if it was ok to replace the black/orange wires on the stock alt with heavier gage. Someone said its ok and to go ahead and do that.

What i did exactly was cut the two black/orange wires and re-attach them to heavier gage cable X 2 that runs to the back of the car where the battery is, from the battery 2 large cables run up the other side of the car to the starter solenoid. Now my question is such, was cutting the 2 stock wires ok? as long as the starter solenoid is getting + from the battery and alt i should be ok right. Or is there something in the stock cables that is protecting the alternator, and maybe i screwed something up.

 

[HISSIN50]

I asked a little while ago if it was ok to replace the black/orange wires on the stock alt with heavier gage. Someone said its ok and to go ahead and do that.

What i did exactly was cut the two black/orange wires and re-attach them to heavier gage cable X 2 that runs to the back of the car where the battery is, from the battery 2 large cables run up the other side of the car to the starter solenoid. Now my question is such, was cutting the 2 stock wires ok? as long as the starter solenoid is getting + from the battery and alt i should be ok right. Or is there something in the stock cables that is protecting the alternator, and maybe i screwed something up.

Thanks for the run down. This info from you should help (though probably not from me, but from JR and the other smart folks on here).

I am not quite following what was done with the stock charging cables (I am not sure which end of the stock wires you cut - at the alt or solenoid). But I think Jrichker's method is the best and is how I did mine (wont be the same for you, but the same principles):

The big plug with the charge cables:
You do need to tap into the white/blk stator wire and connect that to the new alt. But that white/blk wire is the ONLY wire that I chose to use from that connector. I taped the end of the connector up and found an out-of-sight home for it. The stock charge wires were not used on the new alternator (or at the alternator side of those wires).

I left the other end of those stock charging cable(s) attached at the solenoid (Did not even touch them at all). I could have ripped that apart to get to the voltage sensing wire so I could affix that one wire, while allowing me to remove the stock charge cable from the solenoid. I did not).

The way I read what you did, do you still have some part of those stock 10 guage wires connected (in series with the new large cable) to the alternator? Said another way, at a min, I would want to have one large cable run from the connector on the back of the alt, to the battery or solenoid. If other wires are run in parallel, that is one's own choice. But I would not connect the stock wires to the new alternator, and then butt splice those wires to your new cable. That whole run of wire will only be as strong as the weakest (numerically largest number AWG) wires - the 10 guage wires.

As an aside, I would want fuse protection on every charge wire attached to the alternator (on the big wire if that is the only wire; on the big and smaller wires if you ran wires in parallel). I dont like doing it the latter way, but people do.

Jrichker has a newer post outlining how to hook up the alternator - it was the basis for how I did mine (matter of fact, I dont think I did one thing differently - that is how good his thinking was on the matter). I am certainly no JR (I joke often that his big toe has more knowledge than I do), but do alright with electrical stuff (I evaluate different ways to do the wiring and chose to follow his very very sound method).

I am sure he and/or others can provide more info (and much more articulately). And I meant no offense if this post was off base. I probably completely missed what you meant.

Good luck bud.

 

[Dbeck002]

Thank you for the reply... Every little bit counts.



My 3G was wired up precisely the way yours is, large cables going to the + terminal from the alt to the battery, the white/black wire is cut from the plug and wired to the new 3G. thats how it always was and it worked fine that way.

So..



Here is the new information I gathered just now.

I tested the ignition switch, it shows 12v when i turn the key, so that works.

I disconnected the big plug with the black/orange cables and LEFT THE OTHER PLUG IN. <<< I'm not sure if this was supposed to be unplugged or plugged in during the above test given to me by the experienced member. But I left it in since he did not specify to unplug.

So the big power plug is unplugged and the other one is plugged in, the black/orange wires show 12v when grounded, obviously. And those cables show 12v when the lead is touching the white/black wire. I'm not sure if this is supposed to happen but its better than showing nothing IMO.

Next...

The white/black wire on the smaller plug shows 12v with the yellow/white wire, im not sure again if this is supposed to show 12v or not.. maybe you guys know..

Next thing...

The white black wire on the smaller plug to the lightgreen/red shows 1000 ohms.

Lastly...


I get different readings if i keep the smaller plug in than out...

So the main questions here are...


1. Do I leave the smaller alternator plug in while conducting the test?

2. Do I leave the blue/red stripe wire on the starter solenoid plugged in while conducting the test?

3. We have to assume the alternators are good and its something else to blame since both alternators are not showing charge and they are both new/repaired. How hard is it to replace that 500 ohm resistor?

I know this is hard to troubleshoot when youre not infront of the car, im doing the best i can to get this info to you guys. I will draw up a picture of exactly how my car is wired up.

 

[Dbeck002]

View attachment 508899


Here is the setup, its really simple. The old plug is discarded, when the 3G was in there....

Now with the stock replacement I have the old plug back in the alt with new cables...

The orange stripes symbolize the power cables. the line next to it is the white/black wire.. and the 3 lines near that one is just the other plug with its wires going to their locations wherever...

 

[Dbeck002]

Update:



The stock replacement alternator is showing charge thank god.


I am very happy that you guys were able to help me find the problem. It was purely a corrded plug where the terminals were pulled back and couldnt make contact. I am going to install the 3G and tell you what I find, so far so good.

 

[Insane3D]

Ok im about to go do the diagnostic on the electrical.

But before i do i want you guys to know what i did before with the stock alternator cables.

I asked a little while ago if it was ok to replace the black/orange wires on the stock alt with heavier gage. Someone said its ok and to go ahead and do that.

What i did exactly was cut the two black/orange wires and re-attach them to heavier gage cable X 2 that runs to the back of the car where the battery is, from the battery 2 large cables run up the other side of the car to the starter solenoid. Now my question is such, was cutting the 2 stock wires ok? as long as the starter solenoid is getting + from the battery and alt i should be ok right. Or is there something in the stock cables that is protecting the alternator, and maybe i screwed something up.

Hissin already sort of answered this, but I thought my reply from another thread might help too since there seems to be a lot of confusion about the stock charging lead...

Not to step on anyone's toes, but IMO either way is fine with the old charging wire(s). It's probably best to do what jrichker suggested, and not connect them at all. However, if you did connect them, you would still be pretty safe because there are fused links on the old leads.

The stock setup consists of two ~6" lengths of black/orange 10ga wire, which are spliced with a fused link to a single 8ga black/orange wire. This is the main power lead for the stock alternator. It's about 9' long, and runs from the alternator area, in front of the radiator, and then connects to a 12ga brown wire (which is only about 4" long and spliced to the yellow/white voltage regulator sense/switch lead) at another fused link. These two wires go to one singe 8ga green lead, which ends in a ring terminal with yet another fused link, and it connects to the starter solenoid.

Now, to answer sgarlic's question...

I realize that you have far more knowledge and experience than most other people who post here, but I've read 5 or so magazine articles about doing the 3g upgrade, and they all say to make sure to reconnect those wires, supposedly because there are circuits which depend on power from those wires, which apparently aren't satisfied by the 4 gauge wire you run. I'd like to see a full wiring diagram to prove that wrong once and for all, because I personally would like to know which way is correct.

Those articles are partially right. The problem they are talking about arises when you just pull the whole factory power lead out. If you disconnect it at the solenoid too, you are cutting power to the voltage regulators sense/switch line, and this causes problems obviously. Even if you don't connect the old power lead(s) to the new alternator, the sense/switch lead has power because it's still connected at the solenoid. If you take out the factory power lead all together, you just need wire the sense/switch lead to another source. The downside to this is even if you have the power leads disconnected at the alternator, they are still live, so you need to be careful if you just tie them back. If you insist on doing it that way, it's best to cut the ends clean, and tape/heat shrink them up good.

All that being said, IMO, the best way to do it is to rewire the sense/switch lead to the main charging post on the 3G, and disconnect the power leads at both ends so you don't have live and old wiring hot for no reason. I personally opened up the made in Mexico *cringe* wiring bundles , and pulled the whole thing out and just rewired everything. I figure if you are going to upgrade the charging system, you might as well take the time to just rewire everything right, and you'll never have to worry about it again. The more I worked with the factory Ford wiring, the more I wanted to tear it all out.

I hope this clears things up...





Here's a pic of the solenoid side of the factory charging lead...

 

[Dbeck002]

Yep thats how it looks alright. I know exactly what you mean too, that was a question I had earlier, whether or not there is important sh1t still inline with the old cables that need stay there. Of course you just answered that. Thanks

 

[04sleeper]

If you are going to go with the 3G then I suggest getting a new plug as well like this.

Its only $20 from here.