Having an issue with a new/remanufactured alternator not charging, I'm adopting a CS-130 alternator form a 7.4 liter , I need the 12 o'clock/6 o'clock mounting for my application
Fuses are good, all wiring associated with the alternator has been double checked, voltage is where voltage needs to be per the diagram below. I did jumper the battery post on the alternator to the "S" pin on the connector as suggested by someone on another TGO post, still the alternator was not charging. I've had this alternator tested twice, once a few months ago and the second last night, both times it past at my local AZ. I'm wondering if my not charging issue is either a defect that the test set at AZ is not picking up or my problem is a difference in the voltage regulators. The schematic below shows the regulator plug being a PLIS configuration and the new alternator regulator plug is marked as PL I/F S. Is the "I/F" a either/or arrangement as in a universal regulator? The car has a volt meter gauge and not a warning light. I'm having difficulty finding a schematic online like the one below that shows the internal details of the 7.4 alternator for comparison.

Through my searching on the interwebs I have come across a good source of information on alternators
12V DC Wiring Bible - Part 2 -Tech Article by BillaVista - Pirate4x4x.com
On that page there is some description on the differences of the I/F

Alternator will have either an "F" terminal or an "I" terminal, but not both.

• If the alternator has an "F" terminal (i.e. no "I" terminal):
  • It must be excited by the L terminal.
  • When exciting via the L terminal, there must be some resistance in the circuit (bulb and/or resistor) or a short circuit will be created.
  • If no alternator warning lamp is desired, a 50 Ohm resistor is used.
  • If an alternator warning lamp is used, a resistor should still be used, in parallel with the lamp. This is so that the bulb burning out does not prevent current flow and therefore alternator excitation. The resistor should be equivalent to a 3-4 watt bulb. Using Ohms law, we can use the Electrical Wheel of Doom from Part 1 to calculate the required value of the resistor as R = V^2 / Watts. In this case R = (14v*14v) / 4W = 49 Ohms. So a 50 Ohm resistor will do.

• If the alternator has an "I" terminal:
  • You can use this I terminal to excite the alternator, whether or not you are using an alternator warning lamp (i.e. whether or not anything is connected to terminal L).
  • Terminal "I" has a built-in internal resistor to prevent a short circuit when connected to the exciter wire. Therefore, you can connect the ignition switch to terminal "I" using an exciter wire with or without a resistor in series.
  • If you do not have or do not wish to install an alternator warning lamp, you can excite the alternator by connecting the ignition switch to terminal "I" using an exciter wire with or without a resistor in series.
  • If you do have an alternator warning lamp connected to terminal "L", you can still connect the the ignition switch to terminal "I" using an exciter wire with or without a resistor in series as a backup method of exciting the alternator. This is good practice as this type of redundancy enhances reliability.

 

On the 4-pin connector only one terminal needs to be wired for it to charge. Either the F or the L terminal.

With the engine running wire +12 volts to the F terminal. That alternator should charge, if not it is bad.

Be sure that the case is grounded to the engine block (usually through the brackets) and that the BAT output to battery cable is good.

Not much else is required for it to charge. Although the F terminal +12V feed needs to be ignition switched. And the S terminal can be used for remote voltage sensing.

RBob.

 

Below is a picture of the voltage regulator plug,
Is I and F interchangeable? I do have switched ignition voltage here.
I was under the impression that L was for a low charge light? I do have the voltage meter not the low charge light, if that makes a difference
I do have a good case ground to the motor, both positive and negative battery cables are brand new
BAT cable in good condition and I do have voltage there that is consistent with the battery voltage.
"With the engine running wire +12 volts to the F terminal. That alternator should charge" with key on I do have voltage consistent with the battery voltage. Could I be losing ignition voltage after start up? tonight with a full charge on the battery and with it running I'll check voltage at the I/F pin.

 

I double checked and I do have voltage at the F pin on the voltage regulator.

 

What is the voltage output from the alternator? Or is it just sitting at battery voltage? If it isn't charging the alternator is bad, that is as long as it is also spinning .

Here are what the terminals are for:

P = pulse, used for a tach on diesel engines
L = lamp, used to energize the field via a dash idiot light. And can be lit by the alternator if it isn't charging. Problem is if the dash light burns out or loses connection, no light AND no charging.
F = field, wire ignition switched power to energize the field. Note the internal resistor that takes the place of the light bulb on L terminal. Best way to be wired.
S = sense, used to sense the system voltage at a different point in the harness. Needs to be a heavy gauge wire with a fusible link at the far end.

Terminal F is the only one that is required to charge. Or the L terminal with a bulb.

RBob.

 

With a battery charge of 13.25 charging over night with the trickle charger.
Car running voltage drops to 12.4ish as you can see in the video, she doesn’t appear to be charging, along with verifying voltage at pin F and the squeal coming from the alternator I guess it’s a fair assessment that the alternator is bad?

 

Yea, something wrong with that alternator. The squeal sounds like the brushes are in intermittent contact with the rings.

It does look like there is some output from the alternator, which may be why it passed the auto store testing. But the voltage is too low along with the noise.

RBob.

 

Yeah there’s some interference in there

 

The Sega continues…..
New not refurbished ACDELCO alternator not charging and squealing . Maybe I don’t have the belt tight enough, I can move the alternator pulley by hand. Tomorrow I’m going to take the battery and have it tested to that rule out.


Voltage at alternator same as battery voltage

Voltage at pin F key off

Voltage at pin F key on

Voltage at pin S

1991 Firebird alternator not charging 9/13/22

 

Did a little more digging on voltage regulators and according to Rockauto both the 91 Firebird 5.7 CS-130 and the 91 C/K2500 7.4 CS-130 uses the same voltage regulator across two different manufactures

 

 

Would it be worth Moving or jumper the wire from F to L? Would there be any issues doing that?

BillaVista.com-Alternator Bible Tech Article by BillaVista

• Alternator will have either an “F” terminal or an “I” terminal, but not both.

• If the alternator has an “F” terminal (i.e. no "I" terminal):
  • It must be excited by the L terminal.
  • When exciting via the L terminal, there must be some resistance in the circuit (bulb and/or resistor) or a short circuit will be created.
  • If no alternator warning lamp is desired, a 50 Ohm resistor is used.
  • If an alternator warning lamp is used, a resistor should still be used, in parallel with the lamp. This is so that the bulb burning out does not prevent current flow and therefore alternator excitation. The resistor should be equivalent to a 3-4 watt bulb. Using Ohms law, we can use the Electrical Wheel of Doom from Part 1 to calculate the required value of the resistor as R = V^2 / Watts. In this case R = (14v*14v) / 4W = 49 Ohms. So a 50 Ohm resistor will do.

• If the alternator has an “I” terminal:
  • You can use this I terminal to excite the alternator, whether or not you are using an alternator warning lamp (i.e. whether or not anything is connected to terminal L).
  • Terminal “I” has a built-in internal resistor to prevent a short circuit when connected to the excitor wire. Therefore, you can connect the ignition switch to terminal “I” using an excitor wire with or without a resistor in series.
  • If you do not have or do not wish to install an alternator warning lamp, you can excite the alternator by connecting the ignition switch to terminal “I” using an excitor wire with or without a resistor in series.
  • If you do have an alternator warning lamp connected to terminal “L”, you can still connect the the ignition switch to terminal “I” using an excitor wire with or without a resistor in series as a backup method of exciting the alternator. This is good practice as this type of redundancy enhances reliability.

 

So you guys are essentially getting down to the Two different Types of Voltage Regulators that would be used within many GM/ Delco/ Delphi Alternators.

The Two Types of Regulators being:
-The PLFS
-The PLIS

They do NOT interchange/ mix and match in terms of the Connection on the "C" Terminal of the Connector (F or I Terminal of the Alternator).
I refer to this Terminal as the: "FGHI" Terminal, depending on the use of the Regulator.

An "F" Terminal Connection would actually be a "Field" Connection...
It could be used to power an Indicator/ Light/ LED, saying that the Alternator is Charging (Light ON = Charging).

As apposed to using the the "L" Terminal with an Indicator/ Light/ LED, saying that the Alternator is NOT Charging (Light ON = NOT Charging).

The "I" Terminal Connection would be the same as the "L" Terminal, but with an internal Resistor (NOT requiring an External 470Ohm Resistor/ LED).

 

In terms of Wiring the Two different types of Voltage Regulators:

-With the PLIS Regulator, use the "I" Terminal with an Ignition source.
Or use the "L" Terminal with a "NO CHARGE" Bulb/ LED or Resistor with an Ignition source.

-With the PLFS Regulator, The "L" Terminal must be used with a "NO CHARGE" Bulb/ LED or Resistor with an Ignition source.
The "F" Terminal is ONLY going to be used as a "CHARGE" Indicator.

 

So two possible regulators and the difference is the use of internal resistors for use with a charge light or a volt gauge? I'm well aware that the Internet is always correct and it's telling me that the 1991 Firebird 5.7 and the 1991 C2500 7.4 both use a CS-130 alternator and they use the same regulator. I still have my old alternator that I took out before making all of the changes to the accessory drive, Don't know why I'm just now thinking about it, I'll check to see which identification that regulator has, I'll also double check the identification that the new regulator has.
Are the PLFS and PLIS regulators interchangeable? Can a regulator be checked/tested with a digital multimeter to give some sort of idea as to it's condition?

 

Look at the Two Schematics that I posted in Post #13...

-Observe the "I" Terminal Connection in the Circuit.
-Observe the "F" Terminal Connection in the other Circuit.

 

What I should of said was are the two different regulators mechanically interchangeable, will the two above regulators both work on the same alternator or are the other components of the alternator only designed to work with it's own regulator? If the regulator on the old alternator is a different identification than the new one that is on the car can the old regulator be installed on the new alternator?
Are there separate schematics for alternators on cars with volt gauges instead of charge lights?

 

Alternator on the left is the old that has the correct mounting for a 91 Firebird
on the right is the ACDELCO for a 91 454 C/K2500-3500 Chevy/GMC truck
both appear to have the same PLFS markings. Is that supposed to be an “I” above the “F”?

 

 

The 2 Different Voltage Regulators always (stock) interchanged "Physically" (meaning fitting to the Alternator).

However the Internal Construction (Circuitry) differs.

That One Terminal can be marked, F,G,H, or I... (Thus, as I said, I call it the "FGHI" Terminal).

 

Ok, I follow you now that That terminal has multiple identifications
In my application is my regulator a “F” or an “I”?

 

Most of the Original Stock CS130 Alternators had the PLIS Regulator...
As shown in your OEM Schematic, in Post #1.
The Regulator in the Schematic is Wired as an "I" Type regulator.
Also why RBob said to use the "I" Position Terminal.

I can not tell 100% from what you have posted which style Regulator, the new Alternator is.
I do NOT want to Post this Information, as it can be harmful to the End-User to attempt in practice.

If you can NOT get the Alternator TO CHARGE...
using an Ignition Source with a 470Ohm Resistor on the "L" Terminal, than (with nothing connected to the "FGHI" Terminal) then there is an issue.

 

I’m using the I/F terminal, on the regulator it’s listed as I/F

What more Information is needed, theres more to identification than PL I/F S?

Like physically harmful? I’m no automotive electrical engineer but I have been in the electrical field for over 20 years, feel free to share in private if you don’t feel comfortable posting on a public forum.

Ok a 470 Ohm resister, what tolerance should be used, 2%, 5%, does it need to be a 1% accurate resister? What wattage 1/2w 1w?

 

0.500 Watt, 470 OHM Resistors are what we used from the Production Line... 2%, or 1% is always ideal.

 

Yeah... I am not sharing more information on that, it has bit me in the *** too many times.
The "Electrical Field" (not in the sense you mentioned) is what you need to be concerned about...
NO Touching certain things please.

 

 

In place of the resistor could use a small light bulb (to the L terminal). Such as a 194 as used for dash idiot lights.

Then at key-on, engine-off the bulb should light up. With a running engine the bulb should be off and the alternator charging.

If either of those doesn't occur, the alternator is bad. Which I thought based on the noise it makes was already the conclusion.

RBob.

 

The alternator in the original posts was replaced by a new ACDELCO unit.

 

OK, I missed that somewhere along the way. So we are no longer working with the squealing alternator.

The lamp idea is still valid. Although something has to be up as we are now at three different alternators and none of them are charging.

RBob.

 

Quote:

Originally Posted by RBob

Although something has to be up as we are now at three different alternators and none of them are charging.

RBob.

To be fair the first alternator, which is the correct mounting configuration alternator was on the car for 20 years with the car sitting in the garage for 15 of those years before I decided to move the alternator to the pass. side and it's not really easy to put it all back to stock to see if the old one still works I don't remember having an issue with the alternator, reason for parking her ended up being fuel pump related.

Agreed on something has to be up, from what I can find on the internet both of these alternators use the same voltage regulator, I posted screen shots above of two different vendors both with the same part numbers for both the 350 f-body and the c/k trucks.
Per the charging schematic posted above I've got battery voltage at both the battery post and pin "S"
There are two ring lugs on the battery post, isolated both have battery voltage.
I've got voltage at pin "I/F" with key on, charging schematic posted above shows the plug side as "F" and the regulator side as "I", per vorteciroc's insight this pin can be used in multiple configurations
The alternator is grounded to the motor, ground strap at the back of the motor along with the ground cable from the battery to the block is new
The fan fuse pulls double duty and supplies switch power to the alternator pin "F", fans work as they should

I'm gonna go through the fuse panel again just to triple check
I ordered a new plug and that resister and they are supposed to be delivered tomorrow, What I don't understand is if the regulators are the same why should I have to use pin "L" with the resistor to get it to charge, I understand why the resistor/indicating light needs to be there to create resistance as to not induce a short, this wasn't needed when I dailyed the car 20 years ago
I swear if I find a blown fuse and it fixes the problem
Sorry rant over

 

It doesn't, this is just another test of the system. It is better to use a lamp then to use a resistor. As you will also get a visual on what the alternator is doing.

RBob.

 

Ok, I’ll need to see what I have.

 

Before LED Indicators (and the 470 Ohm resistor in parallel) for the IPC...

We used to use an 83 Ohm Resistor with a 194 Bulb in Parallel.

 

For testing there is no need for the resistor in parallel with the bulb. That just complicates things.

RBob.

 

Going back to the Schematic in Post #1...

The limited drawing/ representation of the Voltage Regulator: shows the PLIS Design.
(Regardless of the Electrical Connector Terminal Designation being an "F").

This is COMPLETELY clearly shown as the "I" Terminal. It is connected to the Regulator via a Resistor to the "L" Terminal.

There is absolutely NO Connection shown to the "FIield".
Please again reference the differences in the 2 Schematics below:

 

I spliced in a bulb socket using a new alternator plug, with key on bulb lights up and when the engine starts the bulb goes out, red multimeter lead on the battery post and the negative lead on the alternator case.

 

That shows that it is all working correctly. I guess at this time the questions are: is the battery going dead, that is after driving around for a while? Maybe it is charging OK.

Is it possible that the DVM is bad and not displaying the proper voltage?

Alternators are temperature compensated. A hot alternator will charge at a lower voltage. Maybe this is the issue?

At this point, without being able to be there, I'm fairly stumped.

RBob.

 

There are more than likely Main Power and/ or Grounding issues somewhere at hand.

Time to remove connections other than:

-Batt. direct to St. Mot. Sol.
-Batt. to direct to Alt.

-Batt. direct to Engine Block.
-Batt. direct to Chassis.

Those Connections must be DIrect (no Tie in Connections for Testing).
All clean, unbroken... minimal Voltage drop!!!

If all of those are good, start making connections back together one at a time to find issues.

 

I did recently have the battery tested and it tested good
Car is on jack stands so a test drive is out of the question at the momment
Maybe it is charging ok, at idle for the short period of time that it's running it's not losing voltage.

Out of habit due to safety procedures it's always good to test your voltage measuring equipment, test voltage then retest your voltage measuring equipment. Equipment like Tick tracers, DVM's or Non-Contact Voltage Testers. I've tested the A/C voltage in the garage a dozen times now

The alternator is low mounted and in relative close proximity to the pass. side header and they get hot pretty fast, maybe that is contributing?

 

-Batt. direct to St. Mot. Sol. This something I need to revisit I think, Due to the wire routing and changing to an LT1 starter I needed a standoff to keep the wiring at the starter solenoid from being put in an odd place I'm using a steel stand off about an 1'' long, obviously steel is conductive but not as good as copper or aluminum
-Batt. to direct to Alt. The two ring terminals that are connected to the batter post are clean and in good condition.

-Batt. direct to Engine Block. As mentioned earlier in this post the negative cable is brand new with a new ring terminal/lug that is bolted to the driver side head, I'm also using external lock washers to make a better electrical connection.
-Batt. direct to Chassis. This is referring to the smaller gauge negative wire?

 

Maybe It is charging and I'm expecting it to be charging faster and I need to leave things be until I can get it out for a test drive?
Thoughts on the statement below?
Is Car Battery Charging When Idling? - Battery Skills

How Long Does It Take To Charge The Battery While Idling?

The amount of current produced by the alternator depends on the revolutions per minute (RPM) made by the copper coil through the magnetic field. Each alternator has a rated power production at the maximum RPMs.

During idling, the engine is running at the lowest RPM that will keep the engine running. Consequently, the alternator will run at low RPMs and thus produce less current.

When you start the engine, the starter coil requires a lot of power to crank the engine. The battery produces such a burst of power and thus its voltage goes down. When the engine starts, the alternator starts producing the power that recharges the battery to full capacity.

At idling, the alternator will take between 15-30 minutes to fully recharge the battery. If you want the battery to be recharged fast, you may rev the engine. This way, you increase the rotation speed of the engine and therefore the rotation speed of the alternator.

This in turn means more current is being produced by the alternator and therefore the battery will charge faster. Depending on the size of the battery and the power ratings of the alternator, when you rave the engine to about 2,000 revolutions per minute, it will take between 3-7minutes to fully charge the battery after the engine start.

 

Ground Connections:

 

Positive Connections:

 

I understand this diagram is to relocate the battery to the rear, the block to chassis ground in stock form would be the firewall to pass. side head ground?

 

That may very well be contributing to the lower voltage. The cooling air enters the rear of the alternator and exits the front. So it is drawing hot air in directly from the header.

RBob.

 

I'm not sure how the last two diagrams relate to my application?
IPBEC, Instrument Panel Body Electrical Centre?
UBEC, is a kind of external DC voltage regulation?

 

The Battery Location, and the other Components are irrelevant.

The Diagrams are ONLY to show The:

IP = Instrument Panel
U =Underhood

B.E.C. = Bussed Electrical Center (Proper Name for Fuse/ Relay Panel and Power Distribution Center).

 

Per your suggestion I started looking at ground connections and the chassis side wire for the negative cable was lose, not sloppy lose but not tight, the threads in the body are stripped out, not tight = bad connection
So I'll get this fixed, that's got me thinking what would the benefit of adding another chassis ground? If it is where would should I add it? I do have the chassis ground from the pass. head to the firewall, is that ground strap enough?

 

One Heavy Gauge Cable (same Gauge as the Battery Cables) from the Engine direct to Chassis...
Is just fine with a Battery in the Engine Bay (NOT a Ground Strap).

Also the same goes for the Battery Direct to the Chassis...
One Heavy Gauge Cable (same Gauge as the Battery Cables).

 

Cars like ours (3rd-gens) were very lacking in Proper Grounding and Main Power practices.

Cars and Lower Amperage requirement Vehicles, were like this at that point in time.
Trucks and Higher Amperage requirement Vehicles, were far better (similar to Modern Vehicles/ wiring systems).

The Diagrams I Made and Posted in this Thread, are more or less how all new Vehicles are done...
(With my diagrams having some slight improvements over some production Vehicles).