Kill Switch Question (using MikesXS harness)

[dimka pdx]

Hi all,

I am currently putting together the wiring on a cafe project I've been working on this winter, and USUALLY, I am pretty good with wiring...but struggling a bit with this one.

I bought a MikesXS harness they recommended based on my VIN. I think I have a 1980 XS SP2 (if that helps).

Right now, I am having some challenges with the kill switch. If I understand how it should work, there is a 12V coming into the switch, once on, it send the 12v on its way to both the coil and starter relay (maybe the safety relay as well). The starter button functions by grounding to the handle bars and sending this ground to the starter relay.

The new harness plug that goes to the kill switch has two wires that are red w/white stripe and a blue w/white stripe (doesn't match perfectly coloring to factory kill switch wiring). The problem is that the three wires on the new kill switch connection on the new harness are ALL getting a 12V. This doesn't seem right.

What am I missing? Any help would be greatly appriciated...

PS - I've been staring at the harness diagrams forever...but can't find anything off. I would hate to have to gut (take apart the electrical tape) the brand new harness to have to figure out what's going on.

 

[Nooovie]

Maybe this will help?

There are 2 different circuits going on there. The kill switch in off mode "interrupts" the red/white wires (which are power). There are 2 wires involved. The red/white coming in from the fuse box, and the other r/w that runs from the switch and joins the circuit going to safety relay, ignitor unit, and coil.

The blue/white (L/W) wire is the one that runs from the starter to the solenoid. So I would say that the L/W gets grounded by the push of the starter button, providing a ground for the solenoid which gets it's positive from the battery and the 20A circuit, closing the circuit and triggering the solenoid. That's the way it looks like to me anyway.

I have a wiring diagram I can email you if you want. It's for an 81 but should work. I also have a detailed image of the starter circuit if need be.

Somebody please correct me if I'm wrong

 

[dimka pdx]

Nooovie,

Thank you so much for the quick response! ...and thank you for offering a wire diagram (dima@mdcresearch.com).

Your logic makes perfect sense, but my problem is that both of the R/W wires going into the kill switch are seeing 12V power. Looking at other diagrams found on this site, there is a R/W 12V that comes from the fusebox and at the switch, prevents it from continuing on to the coil, safety relay, relay and ignitor unit. I wonder if there is something wrong with the harness, or one of the above mentioned components is faulty.

 

[Nooovie]

You're totally welcome... I have your addy and will email you the goods. Maybe edit your email out so you don't get spam

Looking at the diagram, that kill switch should do exactly what you're saying. Preventing power to those 3 things. Am thinking your kill switch is faulty. I would test two ways... If you have a volt meter with continuity.. see if the terminals of the kill switch remain connected when in off mode.

Or see if you still get a reading if you unplug the kill switch. Maybe measure if both r/w terminals in the connector on the wiring harness still get power. One should be live from the fuse box and the other should be dead. If they are both live, than you'd be looking at something feeding into the circuit somewhere. Which I don't see where. That r/w is basically switched power.

I'm just wiring my bike right now and have a completely naked (without the wrap) stock harness for reference. So if you need me to take pics of something, let me know.

 

[dimka pdx]

Nooovie,

I knew my kill switch was most likely faulty to begin with (and purchased an R1 upgrade - that is not yet wired in). Without the kill switch connected, and at the harness plug for it, I get 12V at both R/W wires...which shouldn't be the case. Only the one from the fuse box should have any kind of a reading.

My guess is that the harness is bad, or one of the units connected downstream is getting power somehow and feeding that circuit. What's really wierd is that the R/W wire should go from the switched on kill switch to the safety relay, then to the relay. However, when I disconnect the safety relay, the starter relay R/W wire still reads 12V, which logically shouldn't read squat.

If you have your harness bare, could you do me a favor and trace the R/W wires FROM the kill switch? I am thinking this is where my problem resides.

 

[retiredgentleman]

You should be able to do a few simple resistance checks to find the problem.

With the key off. Remove the ignition fuse. The ignition fuse has a red/white on one side and a brown on the other side. Using your meter you should measure a low resistance (short) from the fuse red/white to one of the red/whites at the kill switch. The other red/white at the kill switch should be an open circuit from the ignition fuse.

Another possibility. Remove the headlight fuse. Find the 6 wires at the Safety Relay. There should be high resistance (open) between the red/yellow and the red/white at the safety relay.

 

[dimka pdx]

Thank you for the continued advice! I'll try this tomorrow.

My safety relay is six wires...but all diagrams only show four wires. I sure hope I am not referring to this as the wrong part. It is grommeted and has two relays on it.

 

[retiredgentleman]

Just read your new post.

You may have a cross connection at the safety relay. Leave the safety relay diisconnected. Remove the ignition fuse, the signal fuse and the headlight fuse. Put your voltmeter on the red/white at the starter relay. Turn on the key. Should be no voltage at starter relay. Now install one fuse at a time to see which fuse is supplying power to the starter relay.

 

[retiredgentleman]

1980 safety relay shows 6 wires in the Haynes wiring diagram. 2 red/whites, red/yellow, blue/black, black and yellow.

 

[Nooovie]

I took some pics... You've got mail!

 

[dimka pdx]

First and foremost, a million thank yous to those replying!!!

So....I decided to take the brand new Mikesxs harness apart and either something isnt right with the harness, or I am an idiot. I am still fussing with the kill switch gremlins.

So I decided to track the R/w wire, and here are my findings:

1. The R/w splits off from the brown ignition line and goes into the fusebox as ignition.
2. From the fusebox, it goes to multiple spots:
- safety relay
- starter relay
- kill switch
...this means that when the ignition is on, the starter relay will always get power IF the ignition is on.
3. From the kill switch, the R/w wiring continues to the:
- coil
- ignition unit
- safety relay

If everything is plugged in and ignition is on, I get 12v at the coil, ignition unit AND both r/w wires at the safety relay (even when kill switch is completely unplugged)...should not be happening. All of this considered, I think the problem resides in the safety relay.

However, I'd loveu to hear from the other experts on here.

 

[retiredgentleman]

That wiring harness has some errors. The red/white wire that leaves the ignition fuse should only go to the kill switch, and no where else. It must not go to the safety relay or the starter relay..............if it does as you say, then you need to remove those 2 wires.

The red/white that leaves the kill switch should go to 3 places..............the TCI box, the ignition coil, and the safety relay.

There should be a red/white wire leaving the safety relay and going to the starter relay.

 

[dimka pdx]

Thanks for the insight...which proves I am not entirely crazy.

In theory, what's the problem with the safety relay and starter relay getting power with the ignition on (regardless of kill switch)? If the kill switch is off, in the above described scenario, neither the coil nor the ignition unit will get power...so the bike won't run. Right?

Has anyone ever mentioned of issues with MikesXS harnesses? Not sure if I should reach out and see if this a known issue. In theory the fix is easy.

 

[dimka pdx]

Sorry... One more question...

One of the wiring diagrams I have shows the r/w going from the kill switch to the safety relay, then on to another relay, and then the 'starter switch' (not the same as the starter button). The one piece missing from my setup is that second relay...which I assumed is the same as the starter switch... But the diagram has it split out. Am I missing a relay, or is this relay built into starter switch?

 

[retiredgentleman]

You are correct, there is no problem with powering up the safety relay (contacts) and the starter relay with the kill switch open ( engine off). That is how my 78SE is wired. It allows you to crank the engine over with the starter motor, without power to the coils. I like that method, and I have used that to do compression tests.

Yamaha changed the wiring methods as the years went along. It appears that around the 79 models ( and 80 to 83), Yamaha decided to run power to the safety relay contacts and on to the starter relay, from after the kill switch. With the kill switch open, you cannot run the starter motor.

The extra relays you mentioned, appeared on the 81, 82 and 83 models. Those are called ..........starter lockout relay, and sidestand relay depending on which year you are looking at. You don't want or need those relays.

You should be able to correct the wiring errors in that harness, by making sure the ignition fuse supplies power (red/white) only to the kill switch and nothing else. The harness you have appears to have extra wires branching off from the ignition fuse which are by-passing the kill switch.

 

[dimka pdx]

Retiredgentleman,

Thank you so much for all your help! One last question...well maybe.

With the new wiring type where the safety relay and starter relay are powered with the kill switch open, doesn't it technically mean the safety relay is worthless? For that matter, what purpose does it serve? My understanding is that it had to do something about protecting the starter, but in the current configuration, the starter will activate with or without it.

Okay...that was more than one question.

 

[XSLeo]

The safety relay stops the starter when the engine starts. It keeps the starter from working as long as the engine is running.
This doesnt protect the starter as much as the gears between the starter and engine. This way protects the starter gears from being overrun by the engine. With the engine running and you hit the start button the safety relay prevents the starter working, this keeps the gears from engaging the engine.

 

[retiredgentleman]

dimka pdx;

You seem to be confused. With the newer wiring method (79 to 83) , the starter relay (via the safety relay contacts) are NOT powered with the kill switch open.

The safety relay has 2 functions .................one is to cut out the starter motor after the engine starts..............the second function is to turn on the headlight and meter lights.

Read my posts carefully and make yourself a diagram..................if you correct the errors I mentioned then it will work correctly.

 

[dimka pdx]

Thank you retiredgentleman!

When I read your post, I confused the terminoligy of having the switch open (off), versus closed (on). My fault. I think this should cure all my problems at this point.

I also plan to ping MikesXS and let them know of the potential harness issue. This could be a serous liability if the kill switch is inactive in the form they currently sell their product.

 

[retiredgentleman]

Yes, thats a good idea to notify mikesxs of errors. However, in the past they were not receptive of feedback..................its under new owners, so maybe they will be more responsive.

Be sure to let us know how you make out with the wiring corrections.