2000 Yamaha Big Bear 400

[Gwbarm]

Thats the start switch plug I think the pink wire used to be red and white it is the same wire that's in the last photo. The video was very informative but he didn't show how he fixed the grounding issues from the front end which is what I think is going on with mine also   

[Gwbarm]

It doesn't seem to have a 2w4w selector switch it may have from new I haven't got that far into it yet but it does have this that goes to the from differential

[Mech]

In the diagrams I was looking at pink was for the horn. That was the only place it was..  

The diagram also showed the 2/4 wd being engaged with a switch. That big knob probably locks the diff ? 

[Mech]

Have you got all the wiring connected up Gw, as per one of those diagrams.. which all appear to be the same. They even use the same colours..  

If the colours of the wires in the plugs doesn't match the diagrams we have then it is for a different market.. If all the wire colours are right for all the plugs then it is right and so if you connect it all it should work.. 

The temp light is only meant to go with the start button, or if it gets hot. There's a diode to stop the temp switch operating the starter. 

If it's all connected, as per a diagram, then the lights/dash dimming when you press the starter must be a bad connection somewhere, or dud battery.. Starter/earth cables can get dirty connections inside the terminal where the wire goes. 

[Gwbarm]

I do not have the lights wired up the fan ground is unhooked because when I hook it up the fan runs horn is not hooked up and these two wires I haven't figured out where they go yet my guess is the carb heater which appears to be missing.

I took the switch out of the equation and went back to the main wiring harness found the blue/black and black wires made a jumper and theoretically when I touch the two wires together the starter should turn, it did not. Im getting a little embarrassed, this is not that complicated of a system, im at the point that I need to devote my undivided attention to this, I have heard that these big bears had wiring harness problems, but this is the first I have run into. This one has been badly abused and not fixed correctly it has the wrong start stop switch with no place for the choke cable, then there is another start stop switch with the wires cut and the choke cable attached. Thanks for all the help, we will eventually get it figured out.

 

 

 

 

 

 

 

 

 

[mga]

1 hour ago, Gwbarm said:

I do not have the lights wired up the fan ground is unhooked because when I hook it up the fan runs horn is not hooked up and these two wires I haven't figured out where they go yet my guess is the carb heater which appears to be missing.

I took the switch out of the equation and went back to the main wiring harness found the blue/black and black wires made a jumper and theoretically when I touch the two wires together the starter should turn, it did not. Im getting a little embarrassed, this is not that complicated of a system, im at the point that I need to devote my undivided attention to this, I have heard that these big bears had wiring harness problems, but this is the first I have run into. This one has been badly abused and not fixed correctly it has the wrong start stop switch with no place for the choke cable, then there is another start stop switch with the wires cut and the choke cable attached. Thanks for all the help, we will eventually get it figured out.

 

 

 

 

 

 

 

 

 

are those two wires for the carb heater? I never connected mine since it's an aftermarket and i don't think it has a heater. I've read that you don't really need it unless you live where the temps are way below freezing.

also, that lever in your other picture...does that engage/disengage the front drive? I read these are full time 4x4 and that would be a nice option, or did someone install that? Need more pics!  lol

[Mech]

None of the diagrams I have show a carb heater.  

I'd check there was 12v at the R/W wire at relay 8, and that it was getting through relay 8 and out to the Y/B wire going to the ECU. If the bikes in gear Y/B should show 12v, and if it's in neutral it should be shorted to the ecu's earth causing the relay 8 to close it's contacts.. feeding 12 volts to the starter solenoid. If there is 12v to the starter solonoid's (6) L/W wire then the start button should earth the solenoid via the L/B wire and the starter should operate.

Page 335 in the manual shows the start circuit simplified down.

[Gwbarm]

Not sure what those wires are for yet at first thought they were added to my harness but if you have them they went to something the only yellow wire found on schematic s for lighting I haven't got that far yet. The big knob has a cable that goes to front differential it doesn't look factory I thought these had an electronic switch for switching from 2w to 4w I don't have that what does your have. I just bought this thing in July and just getting around to it.

[mga]

HEATER

5FU-83790-00-00

by Yamaha

[Gwbarm]

The yellow wire does look like it fits that connection point.

[Gwbarm]

Thanks for the wiring explanation Mech, I was just reading your post about using the test light, I knew I had a problem with something because I did that test earlier, at the solenoid the red white shows 12.4 volts and the test light burns bright at the blue/ black and blue/white it shows 11.7 volts and the test light is half as bright and I was using the same grounding point on the frame for all tests, where the battery negative bolts. Haven't done the other tests yet but I did these earlier today

[Mech]

I think you mean the relay there Gw, not solenoid..  At the relay the R/W should have 12v, the L/W should have 12v when the relay is closed(neutral switch closed), and nothing when the relay is open. The Y/B that goes to the ecu should have either 12v(or a dull light if a test light is being used, because of the relay's winding resistance) or nothing, depending on whether the neutral switch is closed or not.

And at the start solenoid the L/W should have 12v when the neutral switch is closed, and the L/B wire will have either 12v when the start button is not being pushed (or a dull light if using a test light), or practically zero volts when the button is pushed.

I'm not sure whether, when the neutral switch is closed, it shorts the L/W to earth through the neutral switch, or whether the neutral switch just causes the cdi to short the L/W to the cdi's own earth wire..  If the neutral switch being closed isn't closing the relay, then it would pay to check the cdi's earth as well. If closing the neutral switch does close the relay, sending 12 v to the start solenoid's L/W wire then it's irrelevant.

[Gwbarm]

The measuring of voltage I did was the wires that plug into the solenoid I haven't tested voltage at the relay yet.

[Mech]

But the start solenoid doesn't have R/W wires...  The relay has the R/W wires..

Oh..  never mind that..  I see your solenoid has some internal connections..  It's not a separate wire like is shown in the book..  It does have a R/W I see in your picture.. 

[Gwbarm]

I just checked voltages at the relay both wires red and blue/white have 11.7 then checked with test light red is bright, blue /white is dimmer and black/yellow only has 2 volts and very dim . Checked with relay still attached.

[Mech]

The B/W shouldn't be dimmer. Once the relay contacts close the full battery voltage should be on the B/W. When it's in gear and the relay contacts are open it should not have any voltage. It seems that relay must have dirty contacts.

The Y/B should be dim with a test light when the bike's in gear, It's power is going through the relay's windings, but not being shorted to earth yet. If the bike's in neutral, the power going through the relay's windings gets shorted to earth and so the Y/B wire should show no voltage and no light at all.. If the Y/B is making the light glow when it's in neutral, it's because the Y/B wire isn't getting fully earthed, there is a bad connection somewhere going to earth.

 

[Gwbarm]

Thanks Mech! Finally got the starter rotating with the start button, the cutout relay is bad, there is another identical relay in the harness next to it , it was also bad , not sure what that one is for I looked it up last night and now I can't remember, the joys of getting older. I temporarily put a jumper wire to take place of the relay, still nothing. I checked all the connections again and found a ground wire that bolts to the coil I had left off. I did that because when I attached it the fan would run continuously, but that ground was the problem. Not needing the fan to run now I unplugged the fan from the harness. The starter now rotates with the button and I have good bright voltage where it needs to be. Still no spark yet, but I will continue looking for that problem. I did notice the CDI had a date hand written on it of 2019, im assuming that's when it was replaced. At this point I think I will just start checking for correct resistance on all the coils and go from there.

[Mech]

Onya..  well done.

 

[Mech]

The other relay is for the reverse light, but it's a special one with an internal diode..  They can't be swapped, and you should check they haven't been swapped over.. 

The reverse light circuit also connects to the cdi and stops the cranking if the reverse signal isn't right. The reverse switch is normally open unless it's in reverse. When the switch is open there is 12v going through the relay's diode and windings, and that is going to the ecu and the reverse switch. As long as the reverse switch is open, the ecu will see 12v on that G/W wire that goes to the ecu and reverse switch. When the reverse switch closes it shorts the relays windings to the earth, meaning the voltage on the G/W wire drops to zero, which the ecu detects and so prevents cranking. It means you need that relay in place with the 12v going through it's windings and into the G/W wire or it shouldn't crank.. If it is cranking with only the one relay in place, there is something wrong I think.

I may be wrong about what the reverse switch feed into the cdi is for, it may not be to disable the start, but just to limit power in reverse. In that case I'm wrong about the start situation, but it should still be put right to make sure the cdi doesn't limit the power all the time.

[Gwbarm]

Thanks for the info , they look just alike I will have to check to see if they have been swapped because I tried both in the starter cutoff harness and neither worked, they are the blue things in the photo, also see the other black box just in front of the CDI think they called it the engine controller I haven't tested that to see if its good

 

[Gwbarm]

I just looked I did not see that relay highlighted as part of the starting circuit on the schematic, maybe in the ignition system schematic, ill check . Thank you!

[Mech]

The reverse relay is in the main wiring diagram at the end of the manual. Part 23. See there's a dotted box around the relay.. and the diode is inside the box.. That means it's a part of the relay.

And that other box you think is called an engine controller... well I hope it's not.  haha.. None of the three manuals I've been looking in show any such thing.. 

[Mech]

And yeah, the start circuit doesn't show the reverse switch as being anything to do with it, but in the text it says...

"The starting circuit cut-off relay prevents
the starter from operating when the select
lever is in gear or in reverse and the rear
brake lever is free. In this instance, the start-
ing circuit cut-off relay is off so that current
cannot reach the starter motor."..

That's why I'm not sure of the reverse switch's role in the cdi.. it implies it controls the starter.. but if not then it's to detune the motor when in reverse.. 

[Gwbarm]

I didn't know what it was, and looked on Yamahas OEM parts diagram, on one of the OEM parts buying sites, don't even remember which one, and that's what they called it.

[Mech]

Normally an engine control module would be on a fuel injected motor and it controls fuel and ignition.. I'm no yamaha expert though..  hardly had anything to do with them.

[mga]

9 hours ago, Gwbarm said:

I didn't know what it was, and looked on Yamahas OEM parts diagram, on one of the OEM parts buying sites, don't even remember which one, and that's what they called it.

its the Fan Motor Controller. They list it as a "motor controller", they just left out the word "fan"

[mga]

the two relays...one is a starting circuit cut off relay, the other is the reverse relay, and my post above describes the Fan Motor Control Relay

[Mech]

In the books I'm looking in there is no fan relay..  There's only the starter isolation and the reverse relays

Could it be the fan's circuit breaker ?

How many wires does it have Gw, and what colours ? It should be identifiable by it's plug and wire colours.

[Gwbarm]

I didn't see one on the schematic im looking at either, also when I was looking up parts at Motorsport they showed both cutout and reverse relays the same there must have been quite a few different variations on the 2000 model. The wire colors for the motor controller are blue/white, green/white, brown, black, white

[Mech]

Aren't I seeing five wires in there though ?  And we describe wires by the main colour and then the stripe Gw..  It's a convention..