c6 e38 alternator control settings

[???]

I have an mostly stock c6, bcm still fitted. the stock alt on these cars is kinda junk. aftermarket is super expensive and still kinda blah. it's a 4 pin setup with 12 sense wire, a turn on signal at the L terminal and a pwm load signal back to the ecm.

I picked up a cheap used 2 wire alt from a newer truck. these default to 13.8v. they need a pwm on L terminal to change voltage.
10% = 11.0 V
20% = 11.56 V
30% = 12.12 V
40% = 12.68 V
50% = 13.25 V
60% = 13.81 V
70% = 14.37 V
80% = 14.94 V
90% = 15.5 V


in hp there's a drop down box under voltage control from the stock "not fitted" alt to "fitted". I do seem to be able to get some pwm put out.

but the bad part, I only get the output of I go under scanner special settings and manually turn the L terminal on. soon as I do that the voltage jumps from the default to 14.9ish which seems about 85% duty cycle. if i unselect it, it goes back to default. if I hit off button it doesn't charge at all. which is also weird since you leave it completely unplugged and it still charges at default.

so I have 2 problems, one I don't know why it doesn't turn on the L terminal request on its own after cranking. 2. how do I adjust the duty cycle? I changed some settings and flashed but nothing changed at the meter when manually turned on.


there's a few threads come up under search, but most are for stand alone without a bcm. I still have mine.

any thoughts?

[???]

so today I put the tech 2 on it and looked around.. it has the return duty cycle % just fine to tell the ecm the load, but it just doesn't turn the L terminal on by itself.

if I command it on it goes to 85% and charges at that voltage, if I turn it off, it goes to 14% and goes down to that setting, which is which is why I thought it turned off before when using hp scanner. probably the defaults


shame too, cause man it works good even in default mode. was able to lower my idle I had turned up to try and charge better with the oem. this one is rock solid at all the way down to 650rpms with everything on and I sware the engine runs smoother.

at this point I don't see anything involving the bcm setting wise. I ran thru the full setup options. either the e38 can't really do it, or something isn't defined to enable it. does anyone know a car has the e38 ecm and 2 wire alt controls factory?


kinda bummed

[???]

pic of it putting out 92amps at 750 rpm with a bigger than stock alt pulley and 10% under drive crank pulley.

solid 13.7v at the alt, about half a volt drop at the battery with that much load, and dash reads about 12.9v.

I did a bit of research, the e38 ecm is used in a 2015 chevy SS with the 2 wire. same ecm pins and all. my only guess it it's missing the current sensor input into the bcm. seems to be a much different bcm in the SS. plug wire numbers are different. I'd pick up a sensor and pin it into the bcm as a test if i could.

guess I might have to go the stand alone pwm generator. I really was hoping the ecm could be made to put out a steady duty cycle %.


anyone know how to cross referenced bcm numbers by car?
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[STAGEUP]

I've never had luck with alternator settings against C6 charging issues. I'm pretty sure the BCM has the final call on what the alternator does in the C6. Curious, what spark plugs are you using? Resistor type?

[???]

I've never had luck with alternator settings against C6 charging issues. I'm pretty sure the BCM has the final call on what the alternator does in the C6. Curious, what spark plugs are you using? Resistor type?

spark plugs? yeah just some oem replacements off rock auto. I'd have to pull a plug wire to get a part number.


seems there's a company that makes a box that ties into the can bus and tells the ecm to turn on the alt like a bcm would. it's a bit pricey and I'm trying to find out from them if once it does its thing over can if they alt setting in hp become active. like you can set the output duty cycle %. and use the boost over ride stuff. or if there's just a set output from their box.

[TheMechanic]

Here you go. Regulator swap works. I have done about 10 of them now.
https://www.dirtydingo.com/shop/page...path=4&pID=108

As to BCM's. Put in your info and out comes the numbers.
https://parts-catalog.acdelco.com/ac...php?glsId=aces

Alternator wiring in a nutshell. Also post #21 has the swap.
https://ls1tech.com/forums/conversio...aq-thread.html

[???]

Here you go. Regulator swap works. I have done about 10 of them now.
https://www.dirtydingo.com/shop/page...path=4&pID=108

As to BCM's. Put in your info and out comes the numbers.
https://parts-catalog.acdelco.com/ac...php?glsId=aces

Alternator wiring in a nutshell. Also post #21 has the swap.
https://ls1tech.com/forums/conversio...aq-thread.html

thanks for the info, but seems no one makes a new regulatory for this newer alt. like I can't even find a replacement one for it even with the part number off from it.

guess they haven't caught up with the newer alternators yet. they are referring to them as hairbrush style, since the back heat fens look like a hairbrush.

looking up the bcm, it's only used c6 and XLR. nothing else and has no alt inputs. so I ordered that can bus request box. we shall see if it works correctly.