Blue wires on 89 loom
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Oil warning light is black / red
An the wire other side of bulb is brown if I remember correctI don't think the light is for oil but when it meets the 2 pin plug going into.cdi the other wire coming off that plug is dark blue that I.mentioned earlier an that's. For neutral light
I don't understand what the light blue wire does although it goes to cdi an stator before going to.oil.sender -
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@dan28 Here's a 3NC wiring diagram (3MB is similar but the CDI connectors are slightly different; you should have 3NC or 3MB or 3BN etched on your CDI).
Brown is main feed on Yamahas (think of it as the red wire from the battery, it goes in the main switch as red and comes out as brown). Both neutral and oil lights have a brown wire meaning they get power when you turn on the ignition. Neutral light wire is sky blue which changes to blue at the multiplug for the clocks (but is NOT the same blue wire as the one that goes to the speedo/tacho illumination bulbs; this connects to brown when you turn on the lights), it then goes through the CDI and comes out as sky blue again (not sure what it does in there, possibly connects to the sidestand switch blue/yellow wire if you put the bike in gear with the stand down) and runs directly to the neutral switch (it doesn't go to the stator, just passes through the same 4-pin plug as the stator only has 3 wires coming from it). The neutral switch connects to earth when operated which is why it comes on when you turn in the ignition.
Similarly the red/black wire from the oil light then goes through the oil level sender and changes to black so when the 2T oil runs low and operates the switch in the oil tank, it connects to earth and the oil light comes on.
The clever part is the black/red wire connecting to sky blue via a diode (which only allows current to flow in the direction of the arrow) upstream of the oil level sender unit. This lets the black/red wire earth via the sky blue wire to provide a check that the oil light works when you turn on the ignition and put the bike in neutral, and means it goes out when you put it in gear. And the oil light can still work independently of the neutral light if the oil tank is low.
If the diode wasn't there, the sky blue wire could earth via the black/red wire when the oil light comes on.
As @Calum @MadGyver @SpookDog have said, the neutral light wire passes through the CDI and no-one outside of Yamaha knows exactly what it does in there so I wouldn't go chopping it out. If you really need to get rid of the 2-pin connector to fit the loom into your project, best thing would be to get out the soldering iron/heatshrink and hardwire them together (i.e sky blue to sky blue and blue to blue) purely to get rid of the plastic connector block.
Anyway I might have got this wrong but it's late, and I've walked 12 miles over the Purbeck cliffs this evening for fish and chips in Swanage (a winter occupation for relieving January depression when it's too cold to cycle). Still a bit light-headed from the cold now!
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@dan28 No worries. Also I just remembered, with a lot of those plastic connector blocks you can use a jeweller's screwdriver or a pin to flatten the little tags which anchor the actual terminals into the block, and when you get them out they're just like miniature spade connectors. So if you've got some heatshrink the right size to cover these, you could just push them together without doing any soldering, insulate with heatshrink and hang onto the connector blocks in case you ever need them (and you'll have two less butchered CDI/loom connections).
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It seems you have may have a 3RN (1 to 9) loom. I don’t know what year the RN series started.
Blue & sky blue wires? It’s tied into the oil warning lamp and the side stand switch (also the neutral curcuit) according to the Haynes manual… -
My loom is 1989 it's slightly different to rn don't quote me but I think the rn looms are around 1995 their identical to the 1989 but have a bunch extra wires for the square neutral relay
That's why I m getting confused because the wires tie into each other for example side stand switch from cdi is blue/ yellow but on the diagram your looking at it links up to the blue wire -
Bud! I know! Getting an actual specific diagram isn’t easy…
I’d just do what @HOTSHOT-III said, remove the pin connectors from the block with a precision screwdriver and wrap them. At least until you have the motor up and running without issues…
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The connectors had to be chopped off most of it has been moved / altered
Battery is under seat as is regulator flasher relay an cdi
Ignition is mounted under the seat coming out of the side of the frame so there's not much original wiring left
All the wiring is hidden it goes from the rear light behind the mudguard under the seat along a tube on the frame an splits off left an right and goes into the headlight or through the bars to switchgear etc
I actually bought some terminal keys to depin the connectors
I noticed today the reason I ve got in a muddle with it is because the damaged loom I ve unravelled an mapped out on a board this loom is different to the one fitted to.the bike
So here's where I m up to
Blue from ignition is used to illuminate clocks is no longer needed
2 pin plug from cdi dark blue wire an light blue / white
This blue / white is neutral.light
I need to investigate were the other blue goes an also find the wires for oil sender
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