Jump to content
RS990

Foreman 400 weird sine wave!?

Recommended Posts

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.

Share this post


Link to post
Share on other sites
 
 

Now that you'll are talking about the diode , the 450 and 400 are very similar , my 2002 450 blew the diode in the fuse box once and it wouldn't run , and my 2000 450 doesn't have that diode in the fuse box as the fuse box is different 

 

  • Like 1

Share this post


Link to post
Share on other sites
 
2 hours ago, 87Iroc said:

Welcome to the group. 

 

I know what a sine wave looks like and that looks somewhat OK. I'd go through the trouble diagnosis shown above in the service manual. 

 

I have a little spark tester I use or you can just hold the plug against the head(I can vouch saying it only hurts a bit if it decides to ground through you).... The little window tester I have is a bit less stress and works great.

 

My favored tester looks like this...

 

 

Snap80.jpg

Yes I have a spark tester, I've 4 different models.

Share this post


Link to post
Share on other sites
 
1 hour ago, RS990 said:

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!  😁

On the exact same year machine had no spark  !  With what sounds like the same mix of parts !  Two wires were switched in the aftermarket ( china ) VR , DROVE  ME NUTS !   Cut them changed them around and instant spark ! Do not trust  the colors of the China wires for Your VR tests. Darn thing is still running great to the best of My knowledge . I know this could be a long shot, but just something I have run into.

  • Like 2

Share this post


Link to post
Share on other sites
 
1 minute ago, oldmxrider said:

On the exact same year machine had no spark  !  With what sounds like the same mix of parts !  Two wires were switched in the aftermarket ( china ) VR , DROVE  ME NUTS !   Cut them changed them around and instant spark ! Do not trust  the colors of the China wires for Your VR tests. Darn thing is still running great to the best of My knowledge . I know this could be a long shot, but just something I have run into.

No wire on the VR, it's an integrated plug.

Share this post


Link to post
Share on other sites
 
5 minutes ago, RS990 said:

No wire on the VR, it's an integrated plug.

Yes, I agree !  The ! wires to the plug were not correct !  Took way too many hours to figure it out and drove Me nuts !  I know it is a long shot !  But one I will NEVER forget, been at it longer than You and still always learning !

  • Like 2

Share this post


Link to post
Share on other sites
 
1 hour ago, oldmxrider said:

Yes, I agree !  The ! wires to the plug were not correct !  Took way too many hours to figure it out and drove Me nuts !  I know it is a long shot !  But one I will NEVER forget, been at it longer than You and still always learning !

 

That's what makes it fun, always learning!

Share this post


Link to post
Share on other sites
 
15 hours 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.

When I measure the voltage with a DVM the yellow wire at the ICM I get 6v with VR unplugged and 10v with the VR plugged in but when measure with the DVA I get 0v unplugged and 10v plugged in. The G/W goes to ground like it suppose to. I tested the VR's an both tested the same, red to yellow, open circuit and 0.5v the order way for all three yellows. The ICM gets it 12v through the red wire has it should. We know the signal from the pulser(Bu/Y) is good and I verified that the ICM is getting the signal, I get 4.6v Peak at the ICM.

Share this post


Link to post
Share on other sites
 
15 hours 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.

I tried to verified for spark using an adjustable spark tester and I get a weak spark when I adjust the tester at about 0.010"-0.005".

Share this post


Link to post
Share on other sites
 
 
 
 

It's the ignition coil!! When i checked for the ignition primary to the coil I had nothing and now I have 160v peak?!? I don't know what I did wrong with the test, maybe I forgot to plug something back in or what but now I have ignition primary voltage. Tried the ignition coil from the 1989 350 and lo and behold I have spark!! I feel so freakin' dumb for wasting everyone's time! At least I learn something!

 

Thanks everybody for the help and the learning experience, greatly appreciated!!

Edited by RS990
  • Like 4

Share this post


Link to post
Share on other sites
 

Glad you got it figured out!

 

Don't feel bad about missing something... happens to the best of us.
It's easy to make an assumption and go down the wrong path!

 

Share this post


Link to post
Share on other sites
 
9 minutes ago, oh400ex said:

Glad you got it figured out!

 

Don't feel bad about missing something... happens to the best of us.
It's easy to make an assumption and go down the wrong path!

 

Yea, I've spent hours chasing my tail!!... 🤣.....My customer is gonna have a laugh at this!

  • Like 1

Share this post


Link to post
Share on other sites
 
9 hours ago, RS990 said:

I tried to verified for spark using an adjustable spark tester and I get a weak spark when I adjust the tester at about 0.010"-0.005".

 

The secondary windings in the ignition coil are burnt & shorted. Its a rare occurrence... but a replacement coil should fix it.

Share this post


Link to post
Share on other sites
 
5 hours ago, RS990 said:

It's the ignition coil!!

 

Ooops! Glad ya got it going!

Share this post


Link to post
Share on other sites
 
Just now, retro said:

 

The secondary windings in the ignition coil are burnt & shorted. Its a rare occurrence... but a replacement coil should fix it.

Yes, the secondary winding had 1.4Mohm resistance.

  • Like 1

Share this post


Link to post
Share on other sites
 

Great diagnostic troubleshooting thread ya put together here! Thanks for sharing!

  • Like 1

Share this post


Link to post
Share on other sites
 
1 minute ago, retro said:

Great diagnostic troubleshooting thread ya put together here! Thanks for sharing!

Your welcome, great community and great people in this forum, looking forward for my next diagnostic!

  • Like 3

Share this post


Link to post
Share on other sites
 
 

Glad you fixed it.

 

At least you weren't one of those guys who had the kill switch in the off position (I'm guilty of that)

Share this post


Link to post
Share on other sites
 
8 hours ago, jeepwm69 said:

Glad you fixed it.

 

At least you weren't one of those guys who had the kill switch in the off position (I'm guilty of that)

😂..Did that too not to long ago, I hate it when the starter turn with the kill switch off!! The kill switch should kill the engine and starter!

Edited by RS990

Share this post


Link to post
Share on other sites
 
9 hours ago, jeepwm69 said:

Glad you fixed it.

 

At least you weren't one of those guys who had the kill switch in the off position (I'm guilty of that)

 

 

I bet that happens more than we hear , people just don't want to admit to stuff , so they say something like , I found a connectors I must have forgot to reconnect , LOL 

Share this post


Link to post
Share on other sites
 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...