Alt wiring

[85burb]

I have ben looking around on the net for a while and have not found a good answer to how to wire up the 4 pin 140 amp alternater. Have seen some that say you must use all 4 pins and some that just us 2. Some say if you put power on a certin pin it will instantly distroy the alt. Really dont want to do that at like 200 bucks a piece. Thanks for your help.

[clinebarger]

Originally Posted by 85burb

I have ben looking around on the net for a while and have not found a good answer to how to wire up the 4 pin 140 amp alternater. Have seen some that say you must use all 4 pins and some that just us 2. Some say if you put power on a certin pin it will instantly distroy the alt. Really dont want to do that at like 200 bucks a piece. Thanks for your help.

What year/make/model did the alternator come from? Do you have the original plug for the regulator?

All Gen III alternator voltage regulators were PCM controlled from the factory.

Putting a Resisted ignition voltage (through a light bulb or a resister) to pin B(lamp terminal) should make it charge. Heres some connector veiws with pin locations.

[85burb]

The alt is off a 05 chevy truck. No connector or wires.

[clinebarger]

Originally Posted by 85burb

The alt is off a 05 chevy truck. No connector or wires.

A replacement connector will come with 4 wires pin A & pin D will NOT be used in your application. Try hooking up pin B like I stated & see if it will charge.

[85burb]

I have found this painless Pigtail. It has a digram. Is it correct?
http://static.summitracing.com/globa...nstruction.pdf

[clinebarger]

Originally Posted by 85burb

I have found this painless Pigtail. It has a digram. Is it correct?
http://static.summitracing.com/globa...nstruction.pdf

I cant get the link to work? Something about internal error?

[1970 CST Short Wide]

Originally Posted by clinebarger

What year/make/model did the alternator come from? Do you have the original plug for the regulator?

All Gen III alternator voltage regulators were PCM controlled from the factory.

Putting a Resisted ignition voltage (through a light bulb or a resister) to pin B(lamp terminal) should make it charge. Heres some connector veiws with pin locations.

Thank you, this solved my problem. Alt is charging perfectly

Thanks Again
Steve

[Hart_Rod]

Originally Posted by 1970 CST Short Wide

Thank you, this solved my problem. Alt is charging perfectly

Thanks Again
Steve

What's your voltage reading?

[dayj1]

Just to clarify a little further, the AD244 alternators used on the early Gen III engines used a 4 pin regulator. The Painless part linked above works for those regulators as does the bulb/resistor on the “L” terminal to get it to start charging. If you’re using the factory ECM, I’m not exactly sure why you’d want to use a bulb or resistor, but that’s a subject for another thread

The alternator that Rob is asking about has a 2 pin regulator and is used on the Delco DR44 and Bosch alternators on the late Gen III engines (and all the Gen IV engines). This type of regulator only has the “L” and “F” terminals (no “S” or “P”) and is controlled by a PWM signal on the “L” terminal as shown in the table that I attached above. A bulb or resistor attached to the “L” terminal on this type of regulator won’t hurt it, but it won’t accomplish anything either. It will just charge in “fault” mode at its set point of 13.8 volts (which is exactly what it will do if you just leave it disconnected entirely).

Here is a good article from ACDelco on the later alternators with 2 pin regulators: https://acdelcotechconnect.com/pdf/imtn_V12I305.pdf

After some back and forth about the information above, Rob and I found that ,contrary to what I posted above, the GBCM settings in HP tuners are only available for the Gen IV ECMs and not a Gen III P59 ECM (So you can't "turn off" the GBCM functionality in the programming for Gen III)

It’s also worth pointing out that even though late Gen III and all Gen IV charging systems use alternators with 2 pin, PWM controlled regulators, the systems work differently.

The ACDelco article doesn’t break it down by engine platform, but “Integrated” regulated voltage control is the type that is used by Gen IV and requires the use of the Body Control Module. The Gen IV ECM uses a battery current sensor to feed data to the the BCM where it does some calculations and then instructs the ECM to generate a PWM signal to the alternator to make it charge at the rate shown in the table above.

I don’t think it’s a huge leap to speculate that the reason that it’s possible to turn off the GBCM control in the ECM is because the ECM has the circuitry to generate the appropriate PWM signal to control the alternator.

The second type of regulated voltage control is called *stand-alone” and is used by the late Gen III systems (’05, ’06, and early ’07 for truck engines). Stand alone uses a GBCM instead of a current sensor. The GBCM provides the PWM control for the alternator’s regulator. The Gen III ECM is incapable of providing a PWM signal so the only options here are:

1) Leave with the fixed "fault mode" level of charge
2) Wire in the GBCM to mimic the factory setup (no BCM is needed)
3) Change out the regulator in the alternator from a 2 pin to a 4 pin.

[Sweetc10]

im just confuesed as ever. i need somebody to put into slow people terms haha . so i have a 68 c10 i just put 2005 4.8 in with carb setup. im tring to use the stock altenator on the 4.8. what pigtail do i get and how do i wire it up. im sorry for being a nob. any help and break down without over load of info would be greatly apperciated. thanks again guy.

[87chevy.com]

I have mine wired just like the painless, I used a resistor instead of a light...

[85burb]

well that is good i just ordered the painless one.

[68 c10 ls2]

Yes if are running a Painless engine wiring harness you HAVE TO USE THAT RESISTOR THAT COMES WITH THE PAINLESS PIGTAIL!!! DO NOT USE AN AFTERMARKET UNIVERSAL ONE!!!!! Trust me, i bought a universal pigtail with out that resistor and i went through 5 alt's in 2 years of running my motor setup.

[85burb]

Originally Posted by 68 c10 ls2

Yes if are running a Painless engine wiring harness you HAVE TO USE THAT RESISTOR THAT COMES WITH THE PAINLESS PIGTAIL!!! DO NOT USE AN AFTERMARKET UNIVERSAL ONE!!!!! Trust me, i bought a universal pigtail with out that resistor and i went through 5 alt's in 2 years of running my motor setup.

I dont have the harness. All i have is the pigtail. I am using a carb setup.

[Hart_Rod]

I know this is a really old thread, but I have a couple of questions. What voltage are you getting out of the alternator with it wired like you are talking about? Does the computer have any control over the alternator? I have a Speartech harness with the 2 wire plug for my 2006 motor. It's supposed to have a resistor in the brown wire as talked about above and I'm getting 13.3-5 V on my voltage gauge with the truck running. Does this seem about right? Thanks,

Rob

[dec010974]

Yes, that seems about right. For those who don't know, you can buy a resister from radio shack and solder in the resister between the alternator an the pcm. I have at least twice with good results. Poops I need to doit on the swap also. Dang, how did forget that.

[Hart_Rod]

Originally Posted by dec010974

Yes, that seems about right. For those who don't know, you can buy a resister from radio shack and solder in the resister between the alternator an the pcm. I have at least twice with good results. Poops I need to doit on the swap also. Dang, how did forget that.

Thanks. Still wondering if there are any settings that I can change within the tune that will affect the alternator? Also, what is the purpose of the black module on back of the alternator? Is it a SS regulator? TIA

[dayj1]

Originally Posted by Hart_Rod

Thanks. Still wondering if there are any settings that I can change within the tune that will affect the alternator? Also, what is the purpose of the black module on back of the alternator? Is it a SS regulator? TIA

The module is the voltage regulator. It works by varying the output voltage based on a pulse width modulated (PWM) signal as shown in the attached chart.

From looking at the chart, it would appear that the voltage simply increases as the PWM duty cycle increases. That's true for the most part, but the GM documentation explains that that 100% duty cycle is for diagnostic purposes and results in a 13.8 V output.

Adding a bulb or resistor is generally done by folks running carburetors (they aren't using the factory PCM). The gen III motors up to about '04 are connected directly to the PCM and it handles all the PWM magic. The late gen III stuff ('05, '06, and some '07) incorporated a Generator Battery Control Module (GBCM) which added a layer of confusion because it was a separate module. It's easy to identify the newer alternators because they have a 2 pin regulator instead of 4 pin. There's an option in HP Tuners that is something like "GBCM module" and it can be set to "not fitted". This lets the PCM control the alternator without the input of the GBCM. In case you're wondering why you can't just run the GBCM, it requires the Body Control Module to function.

[Sweetc10]

i have a carb setup and trying to figure this same situation out. any help would be apperciated

[68c10airstream]

The painless link in post 5 is what i did. I got with the local rebuilder and i said i wanted a single wire from the key through a bulb or resistor. I opted for the "L" terminal with a resistor and the "I" terminal is a short wire that goes onto the alternator stud that is wired hot all the time to the battery positive terminal.. Not to confuse anyone but some rebuilders modify it internally so the "I" terminal is connected to the stud and they call these alternators a "single wire hookup".

[Sweetc10]

so could i use the holley plug

Holley 197-400
and thats it?

[dayj1]

Originally Posted by Sweetc10

so could i use the holley plug

Holley 197-400
and thats it?

As long as you have an alternator that it will plug into, yes. A 2005 truck motor would have originally come with an alternator with a 2 pin regulator.

[Sweetc10]

im pretty sure i remember seeing 4 pins when i looked at the connector on back of altenator. this and fans all i got left to do to get her on road. this parts confusing me though