[Juicebox]

Let me start with, hello from Massachusetts. First time owning a Vulcan, and seriously working on a motorcycle. I've been a backyard mechanic all of my adult life, but this bike is a little over my head right now. I didn't know what i was getting myself into.

so lets start with what i bought. an 02 vn750, that apparently the previous owner bought from a shop that did custom work...great. what i have in front of me is a bike where all the electrical, mounting locations, battery cage, has all been removed from stock location, above the goats belly. its just a spaghetti of wires. The R/R, reserve light unit, blinker relay, a Mitsubishi igniter box, and the junction box are all just hanging in the space there the battery is.

Yesterday (the day i bought it), when i first hooked a battery to it, i got absolutely nothing. I got power to the white wire at the key, and 2v coming out from the yellow, etc. at this point the blinkers started working, but after cycling the key a few times, they stopped working. Next, i pulled the key switch apart, cleaned and reassembled, and stopped for the night.

Today, i bought a new AGM battery and when i hook a battery to the bike, and turn the key on, I now get power at the key, and full 12v out to the ignition, and other wires. One problem seemingly solved.

Now, I don't know where to go. probing around with a multimeter, i have 12v power going into the right hand controls with the srop switch in run, and when off, switches to 11.xx volts. nothing changes when i hit the starter button. this is my big issue, no matter what i do, nothing will kick on the starter besides just jumping the starter solenoid. no matter if its in neutral, kick stand up or down, clutch in or not. the plug to thge clutch lever seems fine. i have not found any obvious broken wires yet. im thinking tomorrow im going to have to bite the bullet and unwrap the wiring harness.

I've seen these bikes are plagued with electrical problems, and I'm wondering if i should just cut the crap and rewire the bike, with the solutions found on this forum now, instead of trying to piecemeal everything. am i missing something painfully obvious? can someone point me in the direction of a step by step of how the ignition, starter system works?

Edit: here's a link to an album I'll be uploading any pictures to. Tell what you think or if there's any specific pictures toud like to see.

02 kawasaki vulcan 750 basket case

02 kawasaki vulcan 750 basket case album hosted in ImgBB

ibb.co

 

[Spockster]

There's an orange wire on the kill switch that jumps from the kill switch to the start button, it should have power with the key and kill switch on.

From the start button, the wire runs to a solid state relay, start relay, in the Junction Box. This solid state relay triggers the normal starter solenoid.

Check the pinned threads in the electrical section, there's a color wiring diagram.

Does the neutral and oil light work when you turn the key on?

 

[Juicebox]

There's an orange wire on the kill switch that jumps from the kill switch to the start button, it should have power with the key and kill switch on.

From the start button, the wire runs to a solid state relay, start relay, in the Junction Box. This solid state relay triggers the normal starter solenoid.

Check the pinned threads in the electrical section, there's a color wiring diagram.

Does the neutral and oil light work when you turn the key on?

unfortunately i have no instrument cluster, the custom shop removed all of that sadly, so i cannot answer that currently. i assume the wiring has been tucked into the aftermarket headlight housing, or removed entirely

 

[Spockster]

unfortunately i have no instrument cluster, the custom shop removed all of that sadly, so i cannot answer that currently. i assume the wiring has been tucked into the aftermarket headlight housing, or removed entirely

That's ok, see what you have on that orange wire, there's a bypass mod you can do if the solid state relay is bad.

Which reminds me... Do you hear a faint click from the Junction Box when you hit the start button?

If the orange wire has power and the button works but no faint click, the solid state start relay is bad. Don't need it anyway.

 

[Thorn]

Yeah, the electrical failings of a stock bike are usually the ignition switch or the relays in the junction box. You can bypass the starter relay, and drive the starter solenoid directly from the start button. The Two Wire Mod Please note that this will prevent your headlight from coming on when the engine turns over, so you will also need to do the blue-wire mod to have your headlight turn on at the ignition switch.

 

[Juicebox]

That's ok, see what you have on that orange wire, there's a bypass mod you can do if the solid state relay is bad.

Which reminds me... Do you hear a faint click from the Junction Box when you hit the start button?

If the orange wire has power and the button works but no faint click, the solid state start relay is bad. Don't need it anyway.

So, there's a y/r wire feeding into the stop switch at reads 12.7v with the key on, and switch off. The red wire coming from the stop switch reads 11.5v when kill switch is off, and 12.7v when on. Red wire at the starter button reads 11.9v with the kill switch off, and 12.7v when on. With the button depressed and the kill switch on, it still read 12.7. With the kill switch off, The black/red wire coming from the switch reads 11.4v, when depressed 11.9v. With the kill switch on, it reads 12.4v not depressed, and 12.75v when depressed. Is this normal? To me, it seems like it's back feeding in, I would think the black/red wire would be 0v when not depressed at all times.

As for the neutral light, it is getting 12v coming into the connector, regardless of whether it's in gear or not. The oil pressure light wire has no power.

Edit: I do not hear any clicking from the Junction box.

 

[Spockster]

So, there's a y/r wire feeding into the stop switch at reads 12.7v with the key on, and switch off. The red wire coming from the stop switch reads 11.5v when kill switch is off, and 12.7v when on. Red wire at the starter button reads 11.9v with the kill switch off, and 12.7v when on. With the button depressed and the kill switch on, it still read 12.7. With the kill switch off, The black/red wire coming from the switch reads 11.4v, when depressed 11.9v. With the kill switch on, it reads 12.4v not depressed, and 12.75v when depressed. Is this normal? To me, it seems like it's back feeding in, I would think the black/red wire would be 0v when not depressed at all times.

As for the neutral light, it is getting 12v coming into the connector, regardless of whether it's in gear or not. The oil pressure light wire has no power.

Edit: I do not hear any clicking from the Junction box.

Find the 10-pin plug on the Junction Box and look for the black/red wire, some bikes will have an all black wire instead, being 2002 I think it should be black/red.

Probe the wire with your meter and see if the wire gets 12.7v when you hit the start button.

If that wire gets power with the start button, then you need the Two Wire mod. Or you can get a new Junction Box.

 

[Juicebox]

Find the 10-pin plug on the Junction Box and look for the black/red wire, some bikes will have an all black wire instead, being 2002 I think it should be black/red.

Probe the wire with your meter and see if the wire gets 12.7v when you hit the start button.

If that wire gets power with the start button, then you need the Two Wire mod. Or you can get a new Junction Box.

So i spliced the y/r and bl/r together as found on the forum, and still nothing. any advice on what to check next? im guessing the igniter box? if i jump the posts on the starter relay itll kick on the starter. i should say that the starter relay looks a little crusty, maybe replacing it would help? but still, it seems like its back feeding into the starter button, even with the two wire mod done. i suppose it might be time to fullky unwrap the wiring harness to get a real good look, i just want any advice i can get before jumping that deep into it.

 

[Spockster]

So i spliced the y/r and bl/r together as found on the forum, and still nothing. any advice on what to check next? im guessing the igniter box? if i jump the posts on the starter relay itll kick on the starter. i should say that the starter relay looks a little crusty, maybe replacing it would help? but still, it seems like its back feeding into the starter button, even with the two wire mod done. i suppose it might be time to fullky unwrap the wiring harness to get a real good look, i just want any advice i can get before jumping that deep into it.

If you put 12v to the yellow/red on the solenoid, will the starter crank? If not, the solenoid is probably bad.

 

[Juicebox]

If you put 12v to the yellow/red on the solenoid, will the starter crank? If not, the solenoid is probably bad.

I didn't try that, i will try that tomorrow. since you're responding frequently, if you have a blank canvas and had to start from scratch, what would you do in the battery compartment as far as locating everything. like i mentioned and show in some pictures in that album, i have nothing in the battery compartment, and the stock battery cage will no longer work with the battery i got (its slightly wider than stock)?

 

[Spockster]

Well I'm not sure, there's really only one place to put the battery, then squeeze everything else around that. Not sure if there's any room to enlarge the battery box.

 

[Juicebox]

If you put 12v to the yellow/red on the solenoid, will the starter crank? If not, the solenoid is probably bad.

So, I finally figured out what was wrong....it turns out, being new to these bikes and motorcycles in general, I missed something important. The black/yellow is a ground wire/circuit. When I got the bike everything was disconnected, and there must have been a wire connected to that circuit that was disconnected. I feel stupid for not realizing something that simple, but really happy that I got this bike for 400 with only putting a new starter solenoid and battery in it. Sadly I did cut all the tape from the wiring harness, yay me. I even got it running off of the tank. It starts right up and sounds pretty happy. I think the bike just needs some major maintenance now. So thanks for your help, and for those in the future who might be reading this, always check the black/yellow ground circuit.