How do I test the neutral switch on my 2000 Yamaha Big Bear 400 4X4?

[Gwbarm]

Several things dont seem quite right, when you push the start button you should see the oil light not the neutral light. The neutral light should be lite when its in neutral and the keyswitch is in the on position. When you push on the brake it should allow you to start the machine in gear or if the neutral light is not working, but not cause the neutral light to come on. None of the parts you replaced should have any impact on the neutral light, except maybe the keyswitch but only if you werent getting power anywhere.

[lester]

Oh, good grief! I think that all is good for now. Thanks for all of the help.

[Gwbarm]

Glad you got it fixed.

[Mech]

You can test whether it's a bad contact in the neutral switch by using your ohm gauge down on it's connector. With the switch unplugged, in neutral there should be zero ohms to the engine, and in any gear it should show an open circuit..

[Gwbarm]

👍

[lester]

Next question.

I got it to start but it will only run for maybe about a minute (if I'm lucky) then it will die and has absolutely no electrical power at all, none, nada, nill, NONE. Sometimes it only takes a few minutes for it to regain electrical power, other times it takes hours, but it still will only run for maybe a minute and then has no electrical power.  Suggestions?

[Gwbarm]

Was it doing this before you replaced the neutral switch.

[Mech]

Put a volt gauge on the battery and check it's charging, and regulating.

[Gwbarm]

Loosing spark and dying is one thing, but not to have any power anywhere and then come back without you doing anything is strange. It sounds like the battery is completely shorting out. I would try another battery and see if it does the same.

[lester]

I didn't have to replace the neutral switch, it seems to be working now, and I have replaced the battery. I have also replaced the starter relay assembly, both of the other relay assemblies, and the engine start run off headlight switch. 

[Gwbarm]

 You have replaced a lot of the electronic parts I think i would be looking for a loose connection at the fuse box, look closely at the main power fuse for any abnormalities, or a loose ground causing it to loose complete power. Just for good measure put a battery charger on the battery just to make sure it is fully charged.

[lester]

I'm wondering if the stator would do this? I tested it and got these results;

Connecting to CDI magneto coupler

Pickup coil: Meter (+) lead to white/green wire & meter (-) lead to white/red wire = 524 (within specifications)

Charging/rotor: Meter (+) lead to red wire & meter (-) lead to white/blue wire = 000 (out of specifications)

Charging coil resistance: Meter (+) lead to white 1 wire & meter (-) lead to white 2 or 3 wire = @2k =000 @200 = 6 (out of specifications)

 

[Mech]

A faulty cdi charging winding which read 000 (is that an open circuit or a zero resistance circuit), would probably prevent the bike starting at all.. So that reading might be wrong, or you may just have disturbed a bad connection. You should recheck that test.

And did you test across wires 2-3 for continuity on the battery charge windings ? Your gauge should have read something at the 2K ohm setting, if it read 6 ohm at the 200ohm setting. You need to check your gauge or gauge battery, and redo the test  checking across all three phases.

If the spark plug fires and it can be started, start it and check the battery voltage. Check if it charges, and that it regulates.

You could also, and this might be a good idea to try first,  unplug the regulator in case that is causing the problem.. If it runs then, check the polarity of the battery.

Edited August 9, 2024 by Mech

[lester]

So, it will start without the regulator/rectifier plugged in? I will give that a try. I also thought I might just start it, let it run until electrical stops and then start checking the electrical starting from the battery and working forward. Or do you have other suggestions after I try it without the regulator/rectifier plugged in?

[Mech]

Yeah it's ok to start it without the regulator. Try that.

It was starting in post #36 right ? So charge the battery, unplug the regulator, start it and see if it keeps going.

I'll have other suggestions.. Once we see what happens with the regulator disconnected.

[lester]

Will do. Probably be Sunday before I get a chance to do it.

[lester]

Okay, without the regulator connected it does the same thing. I checked after it loses the electrical power and found out that the starter relay assembly has power to it but not to the plugin, to continue power through it, until it eventually resets. Where do I go from here? If it's not the regulator or the stator and it's cranking fine, so I don't think that the starter is a problem, is it probable that it is the CDI unit?

[Gwbarm]

Thats normal, when you press the start button it sends power to the plugin and activates the soloenoid to send power to the starter. So if its starting when you press the start button all that is good. My expierience with bad CDI is they either work or dont work, and it sounds like yours is working, and i dont think a bad CDI would cause you to loose power everywhere just wouldnt spark or start. The only thing i can think of to cause you to loose all power is the main fuse or a bad ground. I keep thinking it could still be something in the stator pickup coil assembly causing intermittant spark but that also should not cause you to loose all power just wouldnt run .

[lester]

So, what would be making the starter relay trip?

[Mech]

Ok. So plug the regulator back in and turn the headlight on and see if they keep going longer than a minute. If they go longer than the engine runs for(about a minute) then turn them off and start the engine and check the charging is working and regulating. I'm trying to deduce where a bad connection would be here, but really a better way is to use a "voltage drop test"... If you google it it will I'm sure explain how to apply the test in different situations.. and save me a lot of typing.. haha

 

 

[lester]

Tried to start it with the headlights on and it immediately went electronically dead.

[lester]

Well, now I don't even get power to the starter, ARGH! Got any dynamite?

[Gwbarm]

I am going through all the electrical componets in my head trying to figure out what might be causing this. You have 2 relays one is for the fan motor, not to concerned about it at this point, then you have the starter cutout relay ,which if went bad would cause it not to start from the start button. You have the soloenoid that hooks directly to the battery, do you have voltage at that post on the soloenoid, but get nothing when you press the start button. I have seen a bad starter do what is happening to you, it may work, but pulling to much amps from a bad connection either externally or internally, check the terminal where the soloenoid connects to the starter and make sure that terminal is solid with a good connection.  

[lester]

There is power to the starter solenoid and through the solenoid until the electrical fails then the power does not go through the starter solenoid anymore. The plug is loose to the starter solenoid, and it is only 20 amps. I have ordered a 30-amp starter solenoid with a new plug to see if it helps or solves the problem. I have tested the starter a few times and it always tests good. 

[Mech]

Lester.. I said turn the lights on and see how long they went for.. see if they go longer than it goes for with the engine running.

[lester]

MECH.. I said, "Tried to start it with the headlights on and it immediately went electronically dead." I also said "Well, now I don't even get power to the starter, ARGH! Got any dynamite?" lol

[Mech]

You didn't answer the question though Lester..  Does it keep the headlights going for longer than a minute.. Just the headlights.. That's all I'm asking..

And Lester, if you had a read up on "voltage drop test", you'd trace and find this problem in about two minutes.

Testing the charging would narrow the point of the problem right down as well.. 

I'm trying to help here Lester, but I need some cooperation and answers to the questions I raise..

[lester]

Oh, well I messed up and tried to start it with them on. But now, it doesn't have any electrical power at all so I can't turn the headlights on. I have started doing a voltage drop test but had to stop and do other things. I'll get back to it when I can.

[Mech]

It would probably better to use a test light if you have one Lester. It's quicker and simpler to use and it doesn't give false impressions like a digital gauge can.

So at this point if you use a jumper to bridge the two big terminals on the start solenoid it should still crank the engine. If it doesn't then you have a problem with a main battery power or earth cable, or a defective battery.

If you are following that BB400 wiring diagram I posted a page back you'll see the battery power goes to the start solenoid, then from there it goes through a fuse on the solenoid and then off to the regulator and the key switch. You could have a bad power or earth battery cable, a bad connection to the battery, or a battery with an internal bad connection just below it's post, or, the power might be getting through all those places and connections just fine, but then not getting to the fuse on the solenoid, or through the fuse, or it might be a bad connection between the wire going from the fuse to the regulator and then to the key switch. The wire from the fuse to the reg, that could have a dirty contact where the fuse wire and the key switch wire both crimp into that terminal on the reg, or any of that wires terminals. You need to trace the power from the battery out till you find where it stops. I'd start with a gauge or test light's lead attached to the battery earth post and use the light probe to check for power on the positive line. Then if you haven't found any breaks, you could attach the test light to the positive and check the earth wires are both providing a good earth in much the same manner working out on the earth wires..

Edited August 12, 2024 by Mech

[lester]

40 minutes ago, lester said:

Oh, well I messed up and tried to start it with them on. But now, it doesn't have any electrical power at all so I can't turn the headlights on. I have started doing a voltage drop test but had to stop and do other things. I'll get back to it when I can.

By the way, the starter solenoid plug is loose and in pretty bad shape and the solenoid is just a 20-amp instead of a 30-amp, so I have ordered a new plug and 30-amp solenoid. I just think it needed to be done.