Alternator or Voltage Regulator?

[ixei]

1967 GMC C2500 with a 396 is the truck in question.

Brand new battery now.

At idle voltage at battery is 14.9v, not good I know.
With truck off a parasitic drain reading of .8A is read.

Unplugging the pin connector from the regulator drops the drain to .010ma... next to nothing.

Should I be looking to replace the regulator or the alternator, or both just so I can't blame anything else?

First time for me with an externally regulated system.
And I'm just not sure if there is a correlation with the over charging and the battery drain.

[ixei]

Going in the fix the cheapest thing first, I replaced the regulator.
To no avail... the draw is in fact worse now at a whopping 2.7A.

Next up is alternator.

I've also unplugged the horn relay for safe measure.

[VetteVet]

Unplug the blue and white wire plug on the back of the alternator, and see if the drain drops.
You should not see more than .003 milliamps on a good system.
The volts are OK as long as they don't go over 15.
If you decide to go with a new alternator, get an internally regulated one and get rid of the low output external one and the regulator.

Here is the wiring you have now.






Here's how you wire the internal regulated 12 SI alternator.

[ixei]

Originally Posted by VetteVet

Unplug the blue and white wire plug on the back of the alternator, and see if the drain drops.
You should not see more than .003 milliamps on a good system.
The volts are OK as long as they don't go over 15.
If you decide to go with a new alternator, get an internally regulated one and get rid of the low output external one and the regulator.

Here is the wiring you have now.

Attachment 1440299




Here's how you wire the internal regulated 12 SI alternator.


Attachment 1440300

Much appreciated Vette, I've just been going off your older posts to the same problem.

With the two pin plug unplugged drain drops, but is still much too high.
I've already purchased the pieces so maybe next time it all fails again I'll go the internal route.

[gijoecarlos]

Is that for a 1 wire alternator? if not? how can i wire it for a one wire? On digram 2 I noticed the white wire thats fuesed was cut of on my truck. I ran a jumper from that wire to the Alternator and got the needle to move a little but it always goes back to the middle when off? Is that correct? Does it read correct , even when power is off? That brown wire dosnt seem to be connected either? could that be a problem too and maybe im not getting a good reading?

[ixei]

Problem solved... I am an idiot....

I didn't know the center position. On the ignition switch was off.
I'm used to turning all the way to the left and removing the key.
Which apparently means I was leaving her on in accessory.
Not sure why the key comes out in accessory. But nonetheless.

Thank you for all your help.

[VetteVet]

Originally Posted by gijoecarlos

Is that for a 1 wire alternator? if not? how can i wire it for a one wire? On digram 2 I noticed the white wire thats fuesed was cut of on my truck. I ran a jumper from that wire to the Alternator and got the needle to move a little but it always goes back to the middle when off? Is that correct? Does it read correct , even when power is off? That brown wire dosnt seem to be connected either? could that be a problem too and maybe im not getting a good reading?

I think we can solve your problem but we have to sort out exactly what it is and what you have.
Is it an SI alternator and is it charging?
Do you have an external voltage regulator?
Do you have a red wire junction like the one in the diagrams?

The wire you think is white with a fuse is actually a black wire with a white stripe. It is the sister wire to the black one with the fuse in the first and second diagrams. If that wire is missing then one side of the ammeter feed is gone. jumping it to the alternator will give you a reading but not a correct reading. The needle should move to the discharge side whenever the alternator is not charging and a load draw is applied to the battery. Even with the key off it should read discharge when the lights are turned on.

The battery gauge is there to compare the voltages on the battery and the alternator. we need a wire from each one to a different side of the gauge and the end of each wire has to be connected to a separate wire between the alternator and the battery so the gauge can read the difference between the two. This is a simplified version of how it works but I hope it makes it easier to understand.

The brown wire you have is probably the alternator exciter wire to start it charging. It would normally run to the external voltage regulator which is mounted on the radiator support. If this truck has been converted to a one wire alternator, it won't need the brown wire. You will still have to have the
two gauge wires and the fuses. Also the connector wire from the battery to the alternator junction must be used.

See if you can figure out which alternator you have and we'll show you how to get it working.

[gijoecarlos]

No Voltage Regulator and no Juction box yet? I think i might have to add one? I do see one fuse next to the battery but not the second one like the diagram shows but im sure it because of that middle wire (black w white stripe) that is cut off. Is that wire important? Do i need the junction box for sure? On diagram 2, it the ony wires i need the black and red ones? thanks in advance for your help!

[gijoecarlos]

Currently it looks like both the black & red wires are going to the battery and none are going to the alternator. and the middle black with white stripe is just cut off. Not completely, I can splice i wire to it if i need. When i connected the alternator to it with a jumper it made the gadge kinda work but i dont think it works properly.

[VetteVet]

Originally Posted by gijoecarlos

No Voltage Regulator and no Juction box yet? I think i might have to add one? I do see one fuse next to the battery but not the second one like the diagram shows but im sure it because of that middle wire (black w white stripe) that is cut off. Is that wire important? Do i need the junction box for sure? On diagram 2, it the ony wires i need the black and red ones? thanks in advance for your help!

Sounds like some one has cut the voltage regulator and some wires out of the harness. The wire is important if you want the battery gauge to work. If you don't care if it works then you don't need it.If you are running a one wire alternator you can just run everything to the battery. It will work but not as well as a regular three wire.

Originally Posted by gijoecarlos

Currently it looks like both the black & red wires are going to the battery and none are going to the alternator. and the middle black with white stripe is just cut off. Not completely, I can splice i wire to it if i need. When i connected the alternator to it with a jumper it made the gadge kinda work but i dont think it works properly.

It won't work properly unless it's wire correctly like I stated in my first post. It doesn't matter what alternator you use.

Which alternator below do you have?

[gijoecarlos]

I have the 2nd one on bottom! So will the gauge not work without the voltage Regulator?
your right about the Regulator being removed. The 2 wires that are hooked up go to the battery directly and it does run fine but i want to change it so that my Ammeter will work. Thanks again for all the help

[VetteVet]

Well you obviously have a large red wire going into the cab to feed the circuits in the cab,
Ignition switch, light switch, fuse panel, and horn relay. So you need to trace that wire back into the engine compartment to see where it joins the alternator feed wire and the battery feed wire. If this happens to be the positive battery post as I suspect, then you will have to create a common junction point away from both of those in order for the ammeter to work.
I've detailed this in the diagrams in the posts above. You have indicated that one of the ammeter wires has been cut out but you jumped it to the alternator and the ammeter needle moved. The problem is that it can't go directly on the alternator nor can it go directly to the positive on the battery post. Here's why.

Picture the battery and the alternator as two strongmen with a tug of war rope between them. The junction of all the feed wires is the flag in the center of the rope. This is where the ammeter wire ( black/white stripe) goes so it can indicate which one is winning. Refer to the diagrams and you'll see that the alternator feed wire goes there as well. Now when the alternator is charging at a higher voltage than the battery's voltage, the flag ( gauge needle) will read to the right or C. When it's not charging or charging less than the battery's voltage the needle (flag) moves to the left toward discharge.

So here's what you have to do. Get a junction and place it over by the left headlight or on the left inner fender.
Run a 12 gauge red wire from the battery positive junction shown on the right fender,
with a fusible link from the positive battery cable post (as shown), and the black wire for the other ammeter lead, as shown, across the front of the truck over to the alternator junction with the other wires. Tie into this with the cut out part of the ammeter wire and the ammeter will read fairly accurately. There should be a 4 amp fast blow fuse in each ammeter wire to protect it from current surges that would destroy it.

I know this may be confusing to you and many others who don't understand electrical, but if you read through it slowly and follow the details and refer to the diagrams you should be able to sort it out. VV

P.S. Your ammeter will work just fine without the external voltage regulator.

[gijoecarlos]

Awesome! Thanks for the info! Ill keep you posted on how things work out. I got everything i need but the Junction block. Im ordering that today from summit Racing.

Last Question, Is it okay to tap the alternator wire into the red wire by the battery close to the junction block? i only ask because my Alternator is on that side of the motor. Also is it okay to use a blade fuse vs a bus fuse? Might be a stupid question?

Thanks again! Cant wait to have it all working properly!

[VetteVet]

Originally Posted by gijoecarlos

Awesome! Thanks for the info! Ill keep you posted on how things work out. I got everything i need but the Junction block. Im ordering that today from summit Racing.

Last Question, Is it okay to tap the alternator wire into the red wire by the battery close to the junction block? i only ask because my Alternator is on that side of the motor. Also is it okay to use a blade fuse vs a bus fuse? Might be a stupid question?

Thanks again! Cant wait to have it all working properly!

So you have a ride side mounted alternator. Remember I said you have to wire the alternator into the opposite end of the wire that the battery connects to to be able have the ammeter read the difference between the alternator and the battery voltages. This wire is called a SHUNT because it shunts the voltage back and forth from the battery to the alternator. This means that you can't run the alternator power wire close to the battery positive power wire if you want the ammeter to work.

If you just wanted to use a voltmeter like the newer model trucks and cars you wouldn't have to worry about the ammeter wiring.
It's still better to run the alternator wire away from the battery because of a little thing called "voltage drop".

Yes you can use the blade type fuse if it's easier to wire into the ammeter wire.

[gijoecarlos]

On the Digram , it only shows the Fusible link being the only connection to the battery? and not anything else? Should i just run the wire around my motor to get it on that side of the motor to the red wire? And it looks like thats exactly where that other fuse wire also hooks up?
It looks like the alternator is connected to the starter and the starter to the battery, (not sure if this changes things?)

[VetteVet]

Originally Posted by gijoecarlos

On the Digram , it only shows the Fusible link being the only connection to the battery? and not anything else? Should i just run the wire around my motor to get it on that side of the motor to the red wire? And it looks like thats exactly where that other fuse wire also hooks up?
It looks like the alternator is connected to the starter and the starter to the battery, (not sure if this changes things?)

The fusible link is the only wire off the positive side of the battery besides the big cable. One of the fused ammeter wires should connect on that junction along with the SHUNT wire.

Run the shunt wire over the top of the radiator with the ammeter wire, to the left side of the truck. Connect the shunt wire to the junction from summit and run the fused ammeter wire into the cab and connect it to terminal 12 on the cluster plug.

Some one has rerouted the alternator power wire from the back of the alternator to the starter solenoid with the large cable. This will feed juice back up to the battery to charge it and by doing it that way it bypasses the ammeter wiring so it won't work. The alternator feed wire should go to the summit junction along with the other end of the shunt, and the other fused ammeter wire.

The red sensor wire from the alternator no. 2 terminal will also go there.

The fused ammeter wire you connect there will go into the cab and connect to the no. 1 terminal on the cluster plug. I had assumed that you already had these wires and the connections in the cab were made.

The last wire you hook up will be the brown wire to terminal one on the alternator if it's not already connected. This is how you must connect the wires if you want the ammeter to work.

Study the diagrams and you will see how they run.

[gijoecarlos]

Okay That does make sense!! Ill remove the wire from the alternator and run it to the Junction box. It will charge the battery thru the Fusible link?

I will only have 2 wire now coming from the battery, Big wire to the starter and one from the Fusible Link? correct?

I will run one wire from the alternator Stud to the red wire on the Driver side before the radiator support and tie it in the the red wire that runs behind the radiator support to the Junction box just like the the Diagram? At that same tie in spot Ill run the black wire thats it White in the Diagram with a fuse.

That brown wire you said to hook up to the alternator No 1 Terminal? Whats #1 and #2 TERMINALS? Is the stud 1 or 2? and the other with the plug with the red wire the other terminal? My alternator (like pic2) has the wire from the connector to the stud, and the other connector wire going to inside the cab. Stud wire going to starter that im going to re-move from and send to to the Junction box instead. Sorry for the million questions. Just want to do this right the 1st time.

All wire under the dash to the cluster should be fine. None are cut. they only cut ones were in the engine are that i can splice and fix good.

When you refer to Shunt Wire, your just referring to they way the wire is wired on the diagram? Its nbt a special wire, is it?

[gijoecarlos]

is this what you mean by shunt? the long wire?

[gijoecarlos]

http://67-72chevytrucks.com/vboard/a...9&d=1319819569

[VetteVet]

Yes!
If you look at the top diagram in post 3 you can see the shunt wire on the left edge. It is also pictured in the second diagram.

The diagram you linked shows the alternator and regulator in the center of the diagram.
It's where the post 3 diagram came from.
The second diagram is my version of how to wire the internal regulated alternator like yours. It also eliminates the external regulator and some of the wiring.

The linked diagram also shows the ammeter wires and the circled fuses. If you look closely you can see their connections at the battery and at the alternator junction.

Here it is.

[gijoecarlos]

That brown wire you said to hook up to the alternator No 1 Terminal? Whats #1 and #2 TERMINALS? Is the stud 1 or 2? and the other with the plug with the red wire the other terminal? My alternator (like pic2) has the wire from the connector to the stud, and the other connector wire going to inside the cab. Stud wire going to starter that im going to re-move from and send to to the Junction box instead. Sorry for the million questions. Just want to do this right the 1st time.

[VetteVet]

Originally Posted by gijoecarlos

That brown wire you said to hook up to the alternator No 1 Terminal? Whats #1 and #2 TERMINALS? Is the stud 1 or 2? and the other with the plug with the red wire the other terminal? My alternator (like pic2) has the wire from the connector to the stud, and the other connector wire going to inside the cab. Stud wire going to starter that im going to re-move from and send to to the Junction box instead. Sorry for the million questions. Just want to do this right the 1st time.

Look at the top of the alternator and right under the 12:00 is the 1 and 2 terminals. the stud is labeled BAT. The no. 2 wire and the larger Bat wire should go to the junction. The alternator will charge if you loop the no, 2 wire over to the Bat stud, but it will work much better if you run it to the junction.

[toolboxchev]

I have never seen one of those bracket adjusting bolts hold the thread for long.

[gijoecarlos]

Okay looks like i finnaly got it all hooked up!! I think its working but not sure how its originally works. Seems to just go to the middle when the truck if off and moves a little towards the c maybe a 1/4 of the way from the middle? dosnt even hit the half way point from the middle? then when its off it just rolls back to the middle? Should i be getting more movement from the needle than that? It took me a while to hook it all up correctly but im sure its right now. God willing.
I even left the electric fan run with the radio for a while after i turned off the motor and the needle never made it past the half way point towards the D. Now i kinda feel all this work wasnt worth it. will the meter ever go towards the D side? could my ammeter be faulty? Thanks again

[VetteVet]

Originally Posted by gijoecarlos

Okay looks like i finnaly got it all hooked up!! I think its working but not sure how its originally works. Seems to just go to the middle when the truck if off and moves a little towards the c maybe a 1/4 of the way from the middle? dosnt even hit the half way point from the middle? then when its off it just rolls back to the middle? Should i be getting more movement from the needle than that? It took me a while to hook it all up correctly but im sure its right now. God willing.
I even left the electric fan run with the radio for a while after i turned off the motor and the needle never made it past the half way point towards the D. Now i kinda feel all this work wasnt worth it. will the meter ever go towards the D side? could my ammeter be faulty? Thanks again

With the key off turn on the lights and step on the brakes. The needle should go towards D. It usually will stay in the center and run slightly towards charge after cranking the starter or drawing amps like the example you used.
Did you check the fuse in the ammeter wire by the battery?

If you used a voltmeter you wouldn't need the ammeter, but I'd rather have both