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The Terminator X only has PWM-. Do you have a resister recommendation? I've tried this setup without a resistor and no dice. I'm splicing into the 5v sensor feed.
Ok, I installed the resistor to the Terminator's 5v signal wire and tied that into the Terminator's PWM ground signal. It doesn't work. I've tried various duty cycles from 20% to 80% and the voltage coming out of the alt did not change. I checked the pin and it shows 1.9 volts for 30% duty cycle. Obviously, this is an average voltage, but it indicates that the Terminator is working.
Ok, I installed the resistor to the Terminator's 5v signal wire and tied that into the Terminator's PWM ground signal. It doesn't work. I've tried various duty cycles from 20% to 80% and the voltage coming out of the alt did not change. I checked the pin and it shows 1.9 volts for 30% duty cycle. Obviously, this is an average voltage, but it indicates that the Terminator is working.
I agree 20% to 80% should have made the voltage change.
30% should give you about 1.5V, so it sounds like you're got the terminator p- and pullup resistor right. Are you seeing the voltage range from 1V to 4V with 20% to 80%?
My first instinct is to double check that you're not mixing up the L and F terminals.
Double check that the frequency is 128.
Hopefully this alternator hasn't been abused. Running it as you did earlier, without a pullup resistor on P-, should not damage the regulator. I haven't tried it with 12V fearing that it would fry the regulator.
I agree 20% to 80% should have made the voltage change.
30% should give you about 1.5V, so it sounds like you're got the terminator p- and pullup resistor right. Are you seeing the voltage range from 1V to 4V with 20% to 80%?
My first instinct is to double check that you're not mixing up the L and F terminals.
Double check that the frequency is 128.
Hopefully this alternator hasn't been abused. Running it as you did earlier, without a pullup resistor on P-, should not damage the regulator. I haven't tried it with 12V fearing that it would fry the regulator.
It is the L terminal and the frequency is 128. I got the alternator from a junkyard and it only charges at 13.0 volts. I believe that may be the issue.
It is the L terminal and the frequency is 128. I got the alternator from a junkyard and it only charges at 13.0 volts. I believe that may be the issue.
Yeah, that sounds suspect. Should be 13.7 with no inputs.
This is a fantastic thread and solves the issue I will be facing running a newer 2-wire alternator with a older Gen III truck PCM. I have a question for "LSswap" or others that can help: the vehicle I'm swapping into has the older battery dummy light that is grounded via the PCM to turn it on. Is there a way I could retain this functionality with the "page 1"/ PWM solution? If not, no big deal, but the battery light is the only thing in the dash (no volt gauge). Thanks!
This is a fantastic thread and solves the issue I will be facing running a newer 2-wire alternator with a older Gen III truck PCM. I have a question for "LSswap" or others that can help: the vehicle I'm swapping into has the older battery dummy light that is grounded via the PCM to turn it on. Is there a way I could retain this functionality with the "page 1"/ PWM solution? If not, no big deal, but the battery light is the only thing in the dash (no volt gauge). Thanks!
I don't know what the PCM's rules are for the battery light, so I couldn't guess what to change. It may just turn the light on anyway, but I have no clue.
There is nothing straight forward that I can think of from the alternator, that can affect or bypass the light.
So in an ideal world, what would you want the light to tell you? Hypothetically, you could hook something between the F terminal and the light and have the light be brighter or darker depending on how hard that alternator is working, but that's alot of effort for very little info.
I don't know what the PCM's rules are for the battery light, so I couldn't guess what to change. It may just turn the light on anyway, but I have no clue.
There is nothing straight forward that I can think of from the alternator, that can affect or bypass the light.
So in an ideal world, what would you want the light to tell you? Hypothetically, you could hook something between the F terminal and the light and have the light be brighter or darker depending on how hard that alternator is working, but that's alot of effort for very little info.
Honestly, I just like the idea of functioning warning systems/ lights and am aiming for 100% functioning systems. In practice, it'd be nice to know if there was a problem where the alternator stopped charging, for whatever reason. I'll probably be fine without it, as despite my intentions of running a F-body or truck tune, neither support an analog level battery light, such as what is in my instrument cluster (90s GM W-body.) I like your idea of using an Arduino. If I could learn how to build and program one, I could make it do whatever I wanted. I guess this is as good of an excuse as any to learn.
Honestly, I just like the idea of functioning warning systems/ lights and am aiming for 100% functioning systems. In practice, it'd be nice to know if there was a problem where the alternator stopped charging, for whatever reason. I'll probably be fine without it, as despite my intentions of running a F-body or truck tune, neither support an analog level battery light, such as what is in my instrument cluster (90s GM W-body.) I like your idea of using an Arduino. If I could learn how to build and program one, I could make it do whatever I wanted. I guess this is as good of an excuse as any to learn.
Why not just wire in a volt meter to give you clear insight if the alt is charging? Where you connect to can reveal different info (i.e. straight out of alt, at battery, etc.)
i didn't realize i had this style of alternator when i got my car running. i ordered the GM performance CTS V kit and have it running on a Haltech 2500 with the haltech harness. the harness had the same plug so i just plugged it in. one wire was constant 12V and the other was switched with a resister inline. it would just sit at 13.6v then the electric fan would drag it down when it kicked in.
now that i realize what it is im sending a 5V pulse from the haltech to the L pin, it seems to do noting (its not charging at all) when i send a 12V pulse it goes back to the default 13.6.
i'm thinking i fried the regulator when i had 12v going to L and F, but its odd that when it has 12v going to it it still goes to 13.6 vs nothing when its not hooked up.
03-03-2021, 06:12 PM
