Topic: Starter button not working (fixed) now blowing main fuse!

[Corey]

So I have been rewiring my K6 CB750. I got a new wiring harness, left and right hand controls, fuse box, and reg/rect. I thought everything was going fine. That is until I got to the starter button. When I press the button I get nothing. No noise from the solenoid or anything. I'm sure I have it all wired correctly because I've triple checked everything for it. I did a few tests to try and figure out my problem, but my lack of knowledge in this has gotten the best of me (again). So what I have done so far;

1. Triple checked my wiring.
2. Jumped the poles on the solenoid with a screwdriver and it turns over the starter. I didn't start the bike because the tank is off and that's not a priority at the moment.
3. I checked continuity from the yellow/red and green/red wires from the button when it is pressed and that checked out all right.
4. Key switch seems to be working as I get power to the dash lights and front turn signals (only lights I have connected) when in the on position.
5. The bike is in neutral and the safety switch is connected.

When I got the bike it didn't have the starter button. So I can't say if it worked before I started replacing things. All I can guess is that I screwed up somewhere in my wiring and have missed it or maybe my solenoid is bad, but I don't know what to do from here to single out my problem.

[flybox1]

have  you taken apart the starter mechanism to see that all the parts are there, clean, and making contact?
there's a good thread here somewhere of a control rebuild, with good pictures and steps.
i'll try to locate...

[flybox1]

right here... i love this forum 
http://forums.sohc4.net/index.php?topic=80532.0

[Elan]

From your headlight bucket, touch a black wire to your yellow/red going to the starter soleniod. Make sure the key is on. This will tell you if the problem is the button or not

but it could still be the safety system so run a ground to the solenoid to bypass it and do the above test again

[Kurt V]

but it could still be the safety system so run a ground to the solenoid to bypass it and do the above test again

I'm mentioning this only because I have done it: you don't have the bike on the center stand with the kickstand up do you? If so, it ain't gonna start unless you pull in on the clutch.

[Corey]

@flybox1

The right hand control is brand new, and I have it opened up and everything seems to be there and in place.

@Elan

I'll try that and see how it works.

@Kurt V

I don't even have the clutch lever on the bike so that's not a problem.

[goldarrow]

I'm mentioning this only because I have done it: you don't have the bike on the center stand with the kickstand up do you? If so, it ain't gonna start unless you pull in on the clutch.

If bike is in Gear, then you need to pull the clutch, regardless if on kickstand or center stand.

[Elan]

@Kurt V

I don't even have the clutch lever on the bike so that's not a problem.

that would be a problem because the lever needs to be pulled if the safety system wiring is there. its a switch that plugs into the clutch. Unless you bypass it

[Corey]

Ok so I just jumped a wire from black to the yellow/red, and it turns over the starter. So does it mean there is a problem with my shiny new starter button?

[Elan]

Ok so I just jumped a wire from black to the yellow/red, and it turns over the starter. So does it mean there is a problem with my shiny new starter button?

The 750 starter buttons had two versions..

version 1: The positive version used a yellow/red wire that got pressed against a positive wire (black)

version 2: The ground version.. I forget the details, but it worked the button as a ground wire to start the starter.


Maybe you have the "ground version" when your wiring is set up as the "positive version"?  what color wires are coming from your control?

[flybox1]

get the bike in neutral, and hit the starter.

[Corey]

@Elan

It has two wires. The yellow/red and green/red to the starter button, and then there are brown/white, black/red, black/white, and finally black for the headlight on/off switch and the kill switch.

@flybox1

The bike is in neutral. And I have pulled the clutch cable while trying the button. I get nothing.

[Elan]

I think thats the problem. the k6 had a 3 wire button:

yellow/red - this sends positive current to the solenoid
black : this connects to the yellow/red when pressed  giving power
black/red: this shuts off the headlight when the button is pressed to give more power.



You should be able to get the button working by hooking up the green/red wire from the button to a black.

[Elan]

what color wires are coming out of your solenoid?


Heres a great excerpt from hondaman...

HA -- this is hilarious.

I just wired one of these new 73-75 harnesses into a 76 with the black/red third wire out of the starter switch. Wish I would have known about this post BEFORE I went through that.

Got everything to work properly except for the electric start - may work on that tomorrow.

If the Start switch has the Yellow/Red wire (most do) coming from it, match that to the same on the Start solenoid under the seat. Then, if the Start solenoid has a Green/Red wire coming out its other side, try unplugging it from where it is now, and plug it into that spare Green female socket hanging under the seat. Then it will start anytime, not just when in Neutral or de-clutched.

If instead of a Yellow/Red wire, there is only a Black/Yellow wire, try mating that to the Yellow/Red on the Start solenoid, and repeat the above Green/Red to Green switch. For a brief while in 1976/77 the Start switch came from another Honda bike (I think it was the new CX500 family) and it has no Yellow/Red, but instead a Black, Black/Red, and Black/Yellow. There's not a lot of these out there, but since the little plastic switches do fit into the 750 switch housing, they seem to find their way onto these bikes (maybe from junkyards?).

Before the K4, the Start solenoid had a Black and a Yellow/Red wire. The Black is, of course, Ignition 12 volt power. The Start button on the earlier bikes simply grounded the Yellow/Red to the handlebar to kick on the solenoid. the headlight had an OFF/Lo/HI switch on the right side.

Then (actually during the late K3, to be accurate) the Safety Module showed up, which required the clutch be pulled in or the tranny be in Neutral: it then created a "switched on Ground" to the bike on the Dark-Green/Red wire. Since (one side of) the Start solenoid was then connected to this "safety ground" wire to disable starting unless the government (DOT) thought it was OK, the Start switch had to change to supply the 12 volts to the solenoid when pressed, instead of grounding when pressed. So, the Start switch then got 2 wires instead of one, and one of them connected to the Start solenoid (still Yellow/Red) and the other "Black" to the Ignition inside the headlight bucket. This essentially reversed the current flow through the Start solenoid. These bikes had the headlight ON/OFF switch on the right, with the Hi/Lo switch moved over to the left (which I still can't get used to, old dogs...).

The Start-with-headlight-ON issue drained the battery quickly in cold climes, so the Start switch in the late K4 received yet another wire, which is described above. This added 4 more wires to the main harness, though, and it got bulky at the steering head, which often causes chafed wiring right there.

So, a new harness may often be the best fixup, as the old ones may have worn wires in this important area. If you get a used harness, remove the jacket in this section and look over/fix up these wires, then go to www.vintageconnections.com and get some of the newer black jacket (it's cheap) to slip over the harness again.

[Corey]

Thank you so much Elan that worked. I had the green/red plugged into the green/red because it seemed so obvious .

So then I assume based on the differences in wiring I should shut the front headlight off prior to starting the bike, since my control box is wired for the older style and won't turn the light off itself.

[Corey]

The solenoid has yellow/red and green/red. So should I unplug the green/red from the solenoid and plug the green/red from the solenoid into the spare green thus bypassing the starter safety switch?

[Elan]

The solenoid has yellow/red and green/red. So should I unplug the green/red from the solenoid and plug the green/red from the solenoid into the spare green thus bypassing the starter safety switch?

you could, but if your up and running with the safety in place, doesnt hurt to leave it.  you never know that day when your not really paying attention and you had left it in geat and then press the start button. I havent done it but fear I might one day

And if you leave it, remember id your not starting one day, you can plug your solenoid green/red to green bypassing the safety and then you know if the safety was a problem.

[Corey]

All right thank you once again you saved me from kicking the bike over sideways

[Corey]

Bike started right up after sitting for around 8 months and with all my new stuff on it. My new charging system parts are working great. I get a nice 14.5 volts now when around 5-6k (the battery use to not charge). But now I'm blowing the main fuse as soon as I turn the key on whether the kill switch is turned to on or off, and the kill switch does work as I tested it while the bike was running. So now I get to track down another problem.

Something new seems to pop up every time I fix something. I guess that's why it's called a project

[Elan]

So you said you got the bike going, no blown fuses, then you started having the problem? So when you got the button working, it didn't blow the fuse right? What have you done since?

[Elan]

Blowing fuse usually is hot touching ground.

I want to make sure the green/ red coming from the button wasn't acting as a ground for anything else in there

[Corey]

Well the green/red is only connected to the little board for the starter button it doesn't appear to go anywhere else. I messed around with the wires in the headlight bucket a bit. So I'm going to use a tester light at the fuse holder and find my short.

[Elan]

Ok I would disconnect in the headlight all the black wires and brown/ white wires. Then see if the fuse blows. Then plug in the bwrown wires back. Check fuse, then each black till the fuse blows

[Corey]

All right it's getting dark out now so it will have to wait until after I get home from work tomorrow. Then I will just start unplugging things until I find the short.

[Corey]

Okay so I may of found the problem. I disconnected everything in the headlight bucket and open up the handlebar controls to see if any wires are bare from rubbing against the edge of the holes. Everything looked good. Turn key on and no fuses blow. I then plug in the starter button and it still is fine. I proceed to plug in the rest of the wires from the right hand control and it is fine so I screw together the right hand control and try again and now my fuse breaks.

Aha I have found my problem. I open it back up and inspect everything up close. I press the lower piece against the handlebars and I see the little glob of solder holding the green/red wire to the little board is touching the handlebars. The green/red wire is above the yellow/red. This has to be what was blowing my fuse because it only blows when the housing is screwed together on the handlebar. Can I just cover it with something or maybe see if I can sand down the solder a bit to make it no longer touch?