RS990

Sorry if my english doesn't come out like it should it's not my native tongue.

Just now, retro said:

That sine wave may indicate there is a bad stator ground? Does the G/W wire supply a good solid ground?

Not for a honda! I was just throwing that for fun.

That one was a head scratcher, peak volt was good with the DVA! Not honda tho.

Pick-up coil OEM .bmp

2 minutes ago, retro said:

Ya, I don't think the FSM even explains what that AC line is for...? The wiring diagram shows its purpose though.

That why I was suspecting the stator with that weird sine wave, I thought that maybe the ICM doesn't like that signal.

8 minutes ago, retro said:

First verify that the yellow wire that goes to the CDI produces an AC voltage while the voltage regulator is unplugged. If no AC voltage is observed then ya either have a burnt stator, or the G/W wire (stator ground) is broken somewhere between the CDI connector and the Stator. If you see AC voltage, plug the VR back in and test for an AC voltage on the yellow wire at the CDI connector again.

 

You can generally perform a basic regulator diodes test by measuring resistance with your multimeter with one lead on the Red output wire in the connector and the other lead on each of the three Yellow wires in the connector. Reverse your multimeter leads for each yellow wire that ya test. You should see a low resistance (continuity) with current flowing in one direction and a very high resistance (no continuity) while your leads are swapped and current is flowing the other direction through the regulator. Verify that the green wire in the VR connector provides a stator ground too, of course.

The Service Manual should have more about the AC sensor line, there is not much in there to do a proper diagnostic.

2 minutes ago, retro said:

First verify that the yellow wire that goes to the CDI produces an AC voltage while the voltage regulator is unplugged. If no AC voltage is observed then ya either have a burnt stator, or the G/W wire (stator ground) is broken somewhere between the CDI connector and the Stator. If you see AC voltage, plug the VR back in and test for an AC voltage on the yellow wire at the CDI connector again.

 

You can generally perform a basic regulator diodes test by measuring resistance with your multimeter with one lead on the Red output wire in the connector and the other lead on each of the three Yellow wires in the connector. Reverse your multimeter leads for each yellow wire that ya test. You should see a low resistance (continuity) with current flowing in one direction and a very high resistance (no continuity) while your leads are swapped and current is flowing the other direction through the regulator. Verify that the green wire in the VR connector provides a stator ground too, of course.

Good, will check tomorrow if diodes are good, normally should read open circuit one way and about 0.5v the other in diode mode.

8 minutes ago, retro said:

 

If the diode on that yellow AC sensor line inside the VR shorts out, then the CDI shuts down.

Thank Retro, I'm a man of logic and must understand how thing works and why!  👍

Yes I still have the OEM VR, will check tomorrow at the ICM for AC signal and report back. Any way to test the VR?

This is the pulse generator sine wave, looks good!

Pick-up coil.bmp

I'm not to familiar with Honda's ignition system, I've read on another forum that if the VR goes bad it can cause no spark situation. Why?

The customer brought me the parts so i'll ask him if he can return the VR and get an OEM but is budget is limited. AC sensor line that does to the ICM if it's not present will it cause a no spark?

Yes I have the service manual, I followed the procedure in the manual, what's puzzle me is the AC sensor line, the green wire in the 5p connector and the yellow wire in the 4p connector of the ICM should be open but I have some resistance, if I unhook the VR the resistance goes away, manual says nothing about unhooking the VR, tried with a new regulator with the same result, What's the AC sensor line for? I did not test the ignition coil because I don't have any signal that goes to the coil. The ICM is OEM the VR is aftermarket. I do have 12v to the ICM, the Lg/R wire does go to ground. FWIW I have over 25+ year of experience working on ATV'S and Snowmobiles but we learn something new everyday!  😁

Hi, new to the forum, I'm fixing a 1997 foreman 400 with no spark, did the usual test, check the output of the stator and the pick-up coil with a peak volt adapter and everything tested fine, I check to make sure the cdi gets power,  and it does, check wiring, so I ordered a cdi and a voltage regulator and still no spark, took out the oscilloscope to look at the sine wave of the stator output and this is what I got! Does not look normal! I don't have anything to compare to.

AC output stator.bmp