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I had a bad alternator and replaced it recently because the voltage regulator failed. I'm not asking for troubleshooting steps here. I found the problem and corrected the issue by finding out the alternator failed.

While I was waiting for the alternator to arrive, I looked at how the alternator was connected to the electrical system. One thing it said to test is the field windings green connector plug in the back and see if it has 12 volts on one of the two wires on that connector plus the obvious 12 volts on the big stud connector.

So, OK. Just for verification, I will test that wire and see if it works. Of coarse it would work since my regulator was bouncing all over the place.

So, I got to thinking. Where does the other wire go? It's the GND wire. It should go to the frame or right to the battery, right? No! it goes to the ECM. I looked at all the trouble codes the ECM spits out and not one of them has anything to do with the charging system. Not one.

So, do any of you know what the reason is for the GND wire goes to the ECM? What does the ECM do? The description just says it goes to the ECM but it never says whay it goes there.

I have the official maintenance book Honda uses.
 

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the ECM controls all aspects of the engine's running.

The ground wire is to help ensure that all ground points are at the same "near zero" potential.

Never rely on just the frame for a ground.
 

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The ECM is the computer that controls engine functions etc.. As I looked at your schematics I saw it was a ground for the regulator. My best guess is the ECM leaves the ground open at startup. That means the regulator can not turn the alternator on for a few seconds. It is a common practice through out the automotive industry. A big alternator like the 1800 has draws a lot of engine power to spin it. By postponing engaging the alternator allows the engine to settle in and steady itself. Then the alternator would be turned on by giving the regulator a fround. If you grounded it continuously the engine would struggle finding an idle speed etc. when the engine is first started. Of course if that wire was broken or had a bad connection the alternator would never "kick in."
I'm not positive of this but if I am wrong I am sure someone will be by to give the straight scoop. :)

EDIT: It could be a ground that is cut off to hold off the alternator or it could be a hot wire. I did not see any reference to GND in the schematics but maybe it was in the test of the service manual. Doesn't matter if they interrupt the power or ground. I just think it is the wire that delays when the alternator turns on controlled by the ECM. (Computer, PCM, whatever you want to call it) :)

The most recent developments have focused on ‘Smart Charging’; technology that allows the alternator’s regulator and engine ECU to communicate and interact with one another. This emerging technology offers reliability and precision in the control of alternator output generation and distribution. In addition, charging times can be further increased, while it also enhances engine performance, idling stability with soft-start delay and load response control features.

https://www.denso-am.eu/media/corporate-news/2016/june-newsletter-alternator-technology-powered-by-change/



https://gl1800riders.com/forums/5-gl1800-tech-board/245855-alternator-charging-delay.html?action=thread
 

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The ECM is the computer that controls engine functions etc.. As I looked at your schematics I saw it was a ground for the regulator. My best guess is the ECM leaves the ground open at startup. That means the regulator can not turn the alternator on for a few seconds. It is a common practice through out the automotive industry. A big alternator like the 1800 has draws a lot of engine power to spin it. By postponing engaging the alternator allows the engine to settle in and steady itself. Then the alternator would be turned on by giving the regulator a fround. If you grounded it continuously the engine would struggle finding an idle speed etc. when the engine is first started. Of course if that wire was broken or had a bad connection the alternator would never "kick in."
I'm not positive of this but if I am wrong I am sure someone will be by to give the straight scoop. :)
You are exactly right, the alternator doesn't kick in for about 8 seconds after the engine starts.
 

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That was one possibility I thought of but I didn't know if that was it and still don't know if that is it. I know alternators put a lot of resistance on the engine when running.

I didn't say this part but I noticed that everytime I start the bike, the volt meter I installed would stall at 11 volts somewhere then a few seconds later, the volts would creep up to 14 volts indicating a delay.

And, yes. That is the ground wire going to the ECM If you carefully look at one of my pictures, the other wire goes to a few fuses, a kill switch and the ignition switch. Turn the key on and you will have power there.
 

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That was one possibility I thought of but I didn't know if that was it and still don't know if that is it. I know alternators put a lot of resistance on the engine when running.

I didn't say this part but I noticed that everytime I start the bike, the volt meter I installed would stall at 11 volts somewhere then a few seconds later, the volts would creep up to 14 volts indicating a delay.

And, yes. That is the ground wire going to the ECM If you carefully look at one of my pictures, the other wire goes to a few fuses, a kill switch and the ignition switch. Turn the key on and you will have power there.
You might be right but there could be several hot wires or several grounds. Just the vact that there is already a hot doesn't mean there might not be more. It really doesn't matter at this point. Seems that is the wire that delays the soft start alternator.
Some cars even shut the alternator down when you floor the throttle for more power. :) Is your battery up to snuff? Seems like 11 vilts might be a little low. Especially if it is low 11's. Not a big deal but a little low??????
 

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Yep. It's about a year old, the battery.

As to other power to my alternator, there isn't any. I have only 3 wires attached to my alternator.


1. The big fat wire on the stud. (This is the output and always hot.)
2. Only 2 wires on the green connector on the back of the alternator. One power and one ground.



Manual says one wire there will be hot on the green plug and it goes directly to the battery through the ignition switch and the other wire to the computer which is the GND wire.

That's it. No more anything.
 

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Yep. It's about a year old, the battery.

As to other power to my alternator, there isn't any. I have only 3 wires attached to my alternator.


1. The big fat wire on the stud. (This is the output and always hot.)
2. Only 2 wires on the green connector on the back of the alternator. One power and one ground.



Manual says one wire there will be hot on the green plug and it goes directly to the battery through the ignition switch and the other wire to the computer which is the GND wire.

That's it. No more anything.
Correct, you have 3 wires at the alternator, Ignition, Battery, ECM. The alternator's rectifier ground is furnished via the alternator housing.

When you turn on the key, this supplies Ignition sense to the regulator, and sets up the regulator to be turned on, once the engine starts and the ECM provides the GND for the regulator the regulator is operating. The regulator looks at the battery voltage supplied by the White wire and the voltage supplied by the IGN wire, it compares these 2 voltages and based on the presets in the regulator (typically 13.5-14.5 volts) it then supplies voltage to the field windings to start the charging process. Once the 2 voltages match the presets the regulator will reduce the field voltage thereby reducing the voltage/current going to the battery.
 

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Correct, you have 3 wires at the alternator, Ignition, Battery, ECM. The alternator's rectifier ground is furnished via the alternator housing.

When you turn on the key, this supplies Ignition sense to the regulator, and sets up the regulator to be turned on, once the engine starts and the ECM provides the GND for the regulator the regulator is operating. The regulator looks at the battery voltage supplied by the White wire and the voltage supplied by the IGN wire, it compares these 2 voltages and based on the presets in the regulator (typically 13.5-14.5 volts) it then supplies voltage to the field windings to start the charging process. Once the 2 voltages match the presets the regulator will reduce the field voltage thereby reducing the voltage/current going to the battery.
Great explanation.........!!
 

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That was one possibility I thought of but I didn't know if that was it and still don't know if that is it. I know alternators put a lot of resistance on the engine when running.

I didn't say this part but I noticed that everytime I start the bike, the volt meter I installed would stall at 11 volts somewhere then a few seconds later, the volts would creep up to 14 volts indicating a delay.

And, yes. That is the ground wire going to the ECM If you carefully look at one of my pictures, the other wire goes to a few fuses, a kill switch and the ignition switch. Turn the key on and you will have power there.
That is designed into the ECM.
when an 1800 is started, the Alternator field wire does not have any power applied to it on purpose.

that is to keep it from loading the engine when it first starts, so that it can get stabilized and idling correctly.

on average, that delay is around 8 seconds, give or take.
 
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