Topic: In need of some more electric help, cb750k2

[Odin]

Hi again

I been trying to wire up my bike, as i mentioned in an earlier thread, i have a new loom and most of it was easy, but for 2 days now i been stuck in the headlight bucket trying to do the warning/indicator lights.

The turn signal, the turnsignallamps themselves work fine, if i try hook the light blue from the indicator/warning lamp to the light blue on the loom and orange to orange, the indicator lamp only works with the right side turnsignal, i also seem to get some ground issues when i do that, seems the left turn signal bulb glows slightly.

Then the oil pressure waning light, this has a blue with redstripe if memory serves me right, and a black wire, which i think is a black wire shared with the neutral lamp? i cant tell for sure since it so thight between the wires and heatshrinktubing its very hard to acsess properly. However the neutral lamp works fine. No matter what i do, i cant get the oilwarning lamp to light up.
However i used a multimeter and "beeped" the wire going thru the loom down to the pressure switch and put the other end on ground to see if i had a connection, and nothing. I beeped both ends of the wire just to see, and the wire is fine. Shouldnt the pressure switch be grounded? if it should, can this be a result of a faulty switch? i cant remember now but im starting to wonder if i put some thread sealant tape on the threads for the pressure switch, could that be the issue? i dont know if thats enough to not give it ground. Any other suggestions?

Also when i hooked up the flasher relay, there was 3 remaining wires, one green, flat female, one grey flat female, and one black flat female, the flasher relay only had two connectors, grey and black. So where does the flat green female go? most logical to me would be if i had another green wire with a flat male, and ring in the other end, and it goes to battery negative? i cant see it on the wirering diagram.
There was also a round/ring connector green in that area which i grounded to frame, is that correct or have i somehow messed up the green wires and its that one going to the battery?

Sorry for a lot of questions, but at this point im a bit frustrated and confused.

Thanks in advance for you help.

[69cb750]

Blue is right, orange is left, turn signal to right, blue is +12 volts, orange is ground, check with volt meter.

The oil pressure switch needs ground to work, check continuity between switch housing and engine, should be close to 0 ohms.

Flasher relay uses black and gray, green not used.

[The Lone Builder]

Not sure about the turn indicator light issue, but:

The green ring is indeed the earth - goes to frame just aft of the seat latch.

The oil pressure switch is earthed on the engine. Only two things I can suggest; have you checked the bulb and have you checked the switch.

The switch is closed with no pressure (light on), so if you  disconnect the switch and rig up with a battery and test light, the light should come on. Then fire up the engine and the light should go out. If it doesn’t work this way, your switch is u/s - you don’t say what the bike is or it’s condition.

[Odin]

Thanks for your answers

alright, if light blue and orange is positive and negative, then i understand more.

the oil pressureswitch housing does not seem to have continuity to the engine, so then the question is why? faulty switch? or my thread sealant tape?

I have checked the bulb, bulb works, it also works if i ground the wire from/on the switch, but it doesnt work if i ground the switch housing. i dont know what happens when the switches go bad, so does this seem like a typical bad switch issue?

i never had this bike running, and its not ready to start up yet, so i dont really have any clue about if the switch worked or not before.

So the green female flat connector for flasher relay, or at least in the same area, i should just leave hooked to nothing, correct?

also is it correct assumption that neutral indicator and oil pressure indicator share the same black wire?
Also in the headlight bucket, do these get their black/power from a lone black wire? for some reason the neutral indicator seemed to work only when i hooked it to this single black wire instead of the black multiwire connectors, however this could be my just by chance after trying hooking up and taking apart quite a few times today, so i might have confused myself again there.

the bike is a 72 cb750k2

Thanks again for all your help.

[JeffK]

I just went through the same issue with the turn signals and a new loom. You have a ground issue. Try making some alligator clip wires and make some exterior grounds. You will find that the rear turn signal stem is not grounded correctly or that you have missed a ground in the rat's nest up front. Be sure and remember that the bulbs for the front are not the same as the bulbs for the rear. The running lights do not work on the rear but they do work on the front. The turn signals works front and rear.

Let me know hw this info helps you.

Jeff

[Odin]

Thanks

i will keep the grounds in mind, and try add additional grounds as i test just to be sure.

Running lights makes me remember another question, what exactly is the diffrence on the first and second step on the ignition key? whats supposed to work on the first step and not on second?

[The Lone Builder]

alright, if light blue and orange is positive and negative, then i understand more.

I don’t think this is correct. Blue is for right and orange for left. “Negative” is green or earth. The front flashers are earthed by two (one each side) ring connectors that run from stems inside headlight bucket to a common green in the “rats nest”. At the back, IIRC, the earth is to the bolt fastening the lamp the stem.

the oil pressureswitch housing does not seem to have continuity to the engine, so then the question is why? faulty switch? or my thread sealant tape?

I have checked the bulb, bulb works, it also works if i ground the wire from/on the switch, but it doesnt work if i ground the switch housing. i dont know what happens when the switches go bad, so does this seem like a typical bad switch issue?

i never had this bike running, and its not ready to start up yet, so i dont really have any clue about if the switch worked or not before.

Must be the tape; if it’s screwed in, then it is in contact with the engine and “must” have continuity. If you ground the wire to the switch – ie disconnect it from the switch while it is still connected t the bulb –, I think you’re essentially making a circuit from battery, through engine/frame to bulb. Inside the switch there is a diaphragm type arrangement; when pressure comes up, it pushes the diaphragm and opens the switch. This diaphragm can have a hole or other damage and then wont transmit the pressure. You can, again I think, test it by gently using a blunt probe. Don’t push too hard or you’ll puncture a good diaphragm.

So the green female flat connector for flasher relay, or at least in the same area, i should just leave hooked to nothing, correct?

also is it correct assumption that neutral indicator and oil pressure indicator share the same black wire?
Also in the headlight bucket, do these get their black/power from a lone black wire? for some reason the neutral indicator seemed to work only when i hooked it to this single black wire instead of the black multiwire connectors, however this could be my just by chance after trying hooking up and taking apart quite a few times today, so i might have confused myself again there.

the bike is a 72 cb750k2

Thanks again for all your help.

Do you have a stock regulator? This uses green, white and black wires. If it’s replaced with modern reg/react combos, often the green is not required and is therefore spare.

Common black, yes I think so.

Single black to headlight bucket feeds indicators, headlight and runs thro engine kill switch to coils (via black/white).

Don’t mean to be rude, but have you got a wiring diagram; the correct one?

Sean

[The Lone Builder]

Thanks

i will keep the grounds in mind, and try add additional grounds as i test just to be sure.

Running lights makes me remember another question, what exactly is the diffrence on the first and second step on the ignition key? whats supposed to work on the first step and not on second?

First click is everything. Second is parking lights only. On my UK model anyway.

[Odin]

Thanks again

i have stock regulator, all 3 wires are connected there. The green one thats left over would fit nicely on the flasher relay, in fact i automaticly thought it was for that until i went hooking it up. So either im overlooking something or its not supposed to be hooked up.

Ok tomorrow the oil pressure switch will come back out and hopefully i will find out whats going on, seems the wirering i done for it is indeed correct.

Yes the flashers have green ring connectors for ground on the front, im not quite certain how the ground looks at the rear but will check that tomorrow, however seems my biggest issue so far with the turn signal is getting the turnsignal indicator hooked right, since im having issues with it only lighting up to the left forexample, or lighting up when the turn signal is off, pretty much had all the combos today.

About the single black wire, thats helpfull info, but how can that be connected to the kill switch? i have hooked up the black with white stripe so that should be fine, but i dont remember anything going from the single black and to the kill switch? or does that make its way from the black to indicator lamps and up the handlebar? just asking so im sure something havent been "rewired" back in the day.

I have printed out a wirering diagram from here on this website. However the problem is, the right controll switch and some of the wires must have been cut and resoldered, because diffrent colours goes in and diffrent colors goes out, or rather, at least 3 of them are black and then they been heatshrinked and put inside the handlebar. This also seems to be the case on some of the indicator lights, plus they been heatshrinked so thight i have problems accessing the wires to see the colors. Crossed my mind today to just pull everything off and cutting open the heatshrink, but thats quite a bit of work, so im hoping to figure the last few wires out by "beeping" them. Same thing has been done for taillight, 2 wires are green, the rest black, so obviously the colors aint correct, but its easy to figure out whats what back there.

That being said, the green wire around turnsignal relay area, flat female connector, does show on the wirering diagram, at least i cant figure out where it is on there.

Thanks again for all you help.

[The Lone Builder]

Thanks again

i have stock regulator, all 3 wires are connected there. The green one thats left over would fit nicely on the flasher relay, in fact i automaticly thought it was for that until i went hooking it up. So either im overlooking something or its not supposed to be hooked up.
See this post http://forums.sohc4.net/index.php?topic=50156.0


Ok tomorrow the oil pressure switch will come back out and hopefully i will find out whats going on, seems the wirering i done for it is indeed correct.

Yes the flashers have green ring connectors for ground on the front, im not quite certain how the ground looks at the rear but will check that tomorrow, however seems my biggest issue so far with the turn signal is getting the turnsignal indicator hooked right, since im having issues with it only lighting up to the left forexample, or lighting up when the turn signal is off, pretty much had all the combos today.
Now that I think about it, the ground is inside the fitting at the back. he bulb holder is grounded in there and the fitting grounded through the stem. Sorry about the previous mistake.

About the single black wire, thats helpfull info, but how can that be connected to the kill switch? i have hooked up the black with white stripe so that should be fine, but i dont remember anything going from the single black and to the kill switch? or does that make its way from the black to indicator lamps and up the handlebar? just asking so im sure something havent been "rewired" back in the day.
If you check out the wiring diagram, thee is clearly a black going to RH switch

I have printed out a wirering diagram from here on this website. However the problem is, the right controll switch and some of the wires must have been cut and resoldered, because diffrent colours goes in and diffrent colors goes out, or rather, at least 3 of them are black and then they been heatshrinked and put inside the handlebar. This also seems to be the case on some of the indicator lights, plus they been heatshrinked so thight i have problems accessing the wires to see the colors. Crossed my mind today to just pull everything off and cutting open the heatshrink, but thats quite a bit of work, so im hoping to figure the last few wires out by "beeping" them. Same thing has been done for taillight, 2 wires are green, the rest black, so obviously the colors aint correct, but its easy to figure out whats what back there.

That being said, the green wire around turnsignal relay area, flat female connector, does show on the wirering diagram, at least i cant figure out where it is on there.

Thanks again for all you help.

Sounds like you may well have to resort to first principles if all wire colours have changed or are the same. See if this diagram helps; I have circled the bit where the black wires go up to RH switch.

Good luck.



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[bryanj]

The blinker repeater works in an odd way. Either blue or orange is live depending on which side is turned on and the bulb grounds via the ones that are not turned on, you would think it would light the turned off side but due to the magic of resistances and electrickery it dont.
Oil switch if bulb lights with wire a switch grounded but not when connected switch is duff.
Extra green at relay is for 3 wire relay used in different markets.
All black wires should be live(+12volt) when ignition on.

[Odin]

Thanks again for your help.

I got a lot sorted today, i think the blinkers works like they are supposed to now, also the other indicator lamps and switches seems to work,  but the oil pressure switch must be faulty.

Couple of questions. When i turn on high beam, the highbeam indicator lights up like its supposed to, turn it to low beam, the highbeam indicator light glows slightly, also the main headlight bulb light up at low, but can also see the high beam glowing slightly.

Its like some highbeam power bleeding thru somewhere, is this most likely an issue in the handlebar switch, or does it seem like some ground problems maybe? i tried to add additional ground to the bulb just to see, but it didnt change anything.

Also in the headligtbuckett, there one single plain brown wire. I cant see this on the electric schematic, and i cant see anything where this would connect to, is this another wire thats not in use?

My front brakelight switch seems fault, i can press a small screwdriver inside it and get a connection, but i have to press fairly hard, however it doesnt seem to work by brakefluid pressure like it should.
should this move easy when inserting an object into it?

thanks again for ur help

[bryanj]

 Brown wire is for front marker light used in different countries, front brake light switch normally bulletproof but anything this age can go wrong

[Odin]

Yay finally!

the bike is wired up and everything is working, Thanks again for all your great help.

One more question, which is not electric related, where is the rocker cover vent house supposed to go? Any pics of where it routes/lays? i cant really tell from looking at parts diagrams.

Thanks again

[QuimperPen]

If you download the Honda Service Repair Manual for the CB750 from this site look on page 250 for a good description of the routing.