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

[lester]

I picked up a 2000 Big Bear 400 4X4 that was sitting around that I know nothing about. It will not start. I do have a red light when in reverse. When I take it out of reverse, I do not get a green neutral light, and when I push the start button the red oil light comes on but there are no noises, nothing else happens. How do I test the neutral switch and/or bypass it to see if I can get it to at least crank? And does anyone have other suggestions for me to try?

[Mech]

If you put the brake lights on by using the brake lever, then it should be able to start in gear, so that tests all the rest of the circuit except for the neutral switch and relay/relays.

[lester]

With the brake on when I push the start button the red oil light comes on but there are no noises, nothing else happens.

[davefrombc]

From the video I saw of another model,  the  neutral  switch is located low on the left side of the transmission.  Disconnect it and use a test meter to see if it shows open and ground when you  shift in and out of neutral.  If  it tests ok, then  test  the wire to  it for power  with the ignition on  and shifting in and out of neutral.  

To  test to see if the starter itself is ok  you can run a wire directly from  battery  positive and touch it to the positive terminal  on the starter.  If it is ok,   also  check the starter relay.

[lester]

Thanks, I'll give those things a try and post what I find out.

[lester]

Okay, so I have disconnected the neutral switch and can't get it to read as you say, BUT, I have also tried bypassing it by placing a jumper wire between the two wires on the plugin that plugs in to the neutral switch and it does nothing different.

I jumped a heavy gage wire from positive on the battery to the starter and it cranks, the problem is, now I have absolutely no power when I turn the key on. I have checked all of the fuses, and they appear to be good, is there an in-line fuse somewhere? 

More suggestions?

[Mech]

Yamaha change their wiring often. I think we need to get the RIGHT service manual and wiring diagram for that bike.

Here are two that both claim to be your year and BB. Check how many wires the cdi has and let me know and I'll see how many wiring diagrams I can find with the right cdi.. Or, if you have the YMF400 suffix it would help.

00-05bigbear-kodiak400.pdf 2000-2001BB400.pdf

For the lack of power now, after jumping the starter, check the earth contacts and the battery cable to terminals connections, and battery to cable.

[lester]

According to the Vin decoder it is a 2000 YFM400FWN (Big Bear 400).

[Mech]

Ok, and so does it have 11 wires on the cdi, and are the plastic plugs just as shown in that diagram ?

[Mech]

If that is the right diagram then you should check that relay 8 has power to it on the R/W wires, and that the Y/B wire is getting shorted to earth when the brake lights or the neutral lights are on. If both those things are right, then check that the L/W wire on the start relay is 12v, and that it's getting 12v to the start solenoid 6. If the 12v is getting to the L/W wire at the solenoid, check that 12v is getting to the L/B wire on the start button, and that that 12v drops to zero volts when you push the start button.

[Gwbarm]

Yamaha starter cutout relay would cause what you are describing. If it wont start when you pull the front brake lever.

[Mech]

Yeah I always thought a front brake did it on most bikes, but in that diagram I noticed it says it's the back brake switch, and I notice that bike has no brake lights shown in the diagram..  So perhaps this is a different model than the diagram.. 

Check the wiring diagrams against what's actually fitted to the bike Lester. They wire their relays etc in several different ways, and there are several different CDI, stators, pickup coils. The wiring diagrams show the plastic plug shapes and colours and pin locations, all of which they change from year to year and/or market to market. Sometimes they change things half way through a year. The bike always needs checking against the wiring diagram no matter how sure we are about the model and suffix etc.

[lester]

I'll do some looking, it's going to take me a couple of days to dig into it (back to work) so give a bit to get back to you. 

[lester]

I'm not so sure that the CDI would have anything to do with it at this point? It has absolutely no power now, no headlights, no nothing. It's a dead puppy. I'm wondering about the ignition switch, or the kill switch, and if these might be the problems how would I test them? All of the fuses are good unless there are some inline fuses that I don't know about.

[Mech]

Read what I've said Lester.. The cdi does have a lot to do with the starting circuit.

 

[Gwbarm]

I had the same problem with mine and ended up replacing the keyswitch, and both relays before icould get it to power up. They are the 2 black boxes next to the battery tray. 

 

 

 

[lester]

On 6/19/2024 at 3:41 PM, Mech said:

Yamaha change their wiring often. I think we need to get the RIGHT service manual and wiring diagram for that bike.

Here are two that both claim to be your year and BB. Check how many wires the cdi has and let me know and I'll see how many wiring diagrams I can find with the right cdi.. Or, if you have the YMF400 suffix it would help.

00-05bigbear-kodiak400.pdf 58.7 kB · 1 download 2000-2001BB400.pdf 42.05 kB · 1 download

For the lack of power now, after jumping the starter, check the earth contacts and the battery cable to terminals connections, and battery to cable.

It matches the 2000-2001BB. There is no power going to lhe plug.

[Mech]

Which plug ?

I've been giving advice based on that manual, so if you go back and read what and where I say to test for power it should lead us straight to the problem if there is only one problem. If you report back then I can have another look in the diagrams and try to figure if the test is conclusive, whether there could be multiple faults, whether we have the wrong diagram or different parts.

You should use a test light to trace and check for power, a meter doesn't show up bad connections as clearly as the light does.

If you are testing things and reporting back, it helps if you say exactly what you did and found, and to which coloured wires, and at which point in the diagram.

[lester]

Sorry, I was testing at the plug-ins to the CDI. I'll check again and let you know.

[lester]

Also, I'm using my multimeter turned to ground mode (it beeps instead of a light) because I don't have a good testing light. And I tested to the colored wires that you specified. 

[Mech]

Ok, if you don't have a test light, which puts a small load on the circuit when it's lit up, then you need to get familiar with the concept of a "voltage drop test". The gauge will detect 12v even if there is some dirty connection only letting enough power through to make an led go, or the light in your meter light up, but it doesn't mean there is going to be enough power getting through to run anything that needs real power. You will be able to read up on google about voltage drop tests.

Or, improvise a test light using a tail-light and a couple of wires. The light won't light up bright of there's a bad connection you are testing.

[lester]

Sorry I haven't got back, I have been busy and haven't had a chance to work on it for a few days. I will get back when I get a chance to work on it some more.

[Gwbarm]

You have your meter set on the continuity mode, that will tell you if you have a broken wire, put leads on each end of wire it should beep. It wont show voltage. If you use a test light or set meter to DC volts, one lead to wire and one lead to ground, if light lights up you have voltage, and meter will show you how much voltage.

[lester]

Replaced a few electrical parts and it cranks now! Is there a way to adjust the neutral light? The green light comes on when cranking the engine, but not when in neutral (unless you hold the foot pedal in a certain position.

[Mech]

If you are saying that the engine is cranking without the neutral light or the brakes being on, then there is still something not right with the wiring..

That Sb wire that goes to the cdi and neutral switch has to be at earth potential for the cdi to allow the start circuit to work, that wire isn't at earth potential normally because the neutral bulb is letting power through which keeps the Sb wire showing 12v at the neutral switch and the cdi. It's only when the neutral switch shorts the Sb wire to earth, causing the light to come on and the Sb wire to show zero voltage at the cdi that the cdi lets the starter circuit to work.

 

[Mech]

Are you really sure that wiring diagram for the 2000-2001BB400 is the right one ? Are the plastic plugs exactly the same shapes and colours, Look at the stator plug and the regulator plug. Yamaha make a lot of changes and they change plugs shape and colours so we won't and can't muddle them up. The two diagrams I posted won't be the only options, and there will be other options that still use that cdi unit and plugs, but have differences elsewhere..  You really need to be completely sure you have the right model manual or you will get lead down the wrong path..

[Gwbarm]

Which parts did you replace?

[lester]

I replaced the starter solenoid and both relays in the battery compartment, as well as the engine start / run / off headlight switch. Yes, I am pressing the hand brake in order to crank the engine in neutral. Yes, as soon as I start to crank the engine the neutral light comes on, just not before I start cranking. Yes, the plugs are exactly the same shapes and colors as the wiring diagram for the 2000-2001BB400. The pedal is just barely off with the light, just a slight movement will light up the light, that is why I am asking if there is an adjustment. 

[Mech]

Ok. I don't think there will be any adjustment on the switch. They generally have two bolts going through two round holes. You might get a tiny bit of adjustment by virtue of the holes being a bit loose around the bolts, but it won't be much.

The oil temp light is meant to come on when you press the start button..  I don't think there's any reason the neutral light would come on because of that, but it might be worth investigating..

If you don't use the brake, and push the start button, the starter doesn't work, and the neutral light doesn't light up.. right ?

[Mech]

And are you sure the ignition switch is identical in operation to the old one ? They have a few different ones of those.

The relays, they are both identical huh ? And neither of them have a built in diode on the trigger winding ? I've been searching other wiring diagrams and I'm finding other ones that say they do that bike, but they are all different..  haha.