Author Topic: CB400F USA spec wiring diagram question  (Read 6978 times)

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Offline mattsz

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CB400F USA spec wiring diagram question
« on: January 01, 2019, 06:23:36 AM »
Happy New Year!

I'm sorting through the factory wiring diagram (attached) for my bike (a '77), and I'm having trouble sorting out the switch contact grid in the lower left corner - there's contacts on this grid that aren't shown on the diagram's switches.  Can anyone help?

I understand the first section, the turn signals - only I assume that there's two each of L and R because there's a front and rear turn signal bulb - but why use L1, L2 and R1, R2 when there is only one L and one R contact on the switch?

The next section has me confused.  First of all, what is P(F)?  The diagram's switch block has no such contact.  As for the upper position light section, I suppose it's meant to show that when a turn signal is on, the position light for that side is extinguished?  Makes sense, but again, why have two left and two right connections when there's only one switch contact, and in fact only one position light, for each side?

For the sake of argument, in actual function can the L1-L2 and R1-R2 blocks on the chart be condensed simply to L and R?

I get the horn section ( ;) )...

The lower headlight dimmer section also has me scratching my head... again, I wonder about that P(F) contact, but also, what's with the (N) switch position, which shows the high and low beam connected simultaneously?  My bike's switch doesn't have a middle "N" position, just Hi and Lo, with no selection between them.

The ignition and engine stop-starter switch blocks make sense - but if anyone can shed some clarity on the others, I'd be grateful!

Offline Deltarider

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Re: CB400F USA spec wiring diagram question
« Reply #1 on: January 01, 2019, 06:54:56 AM »
Just a guess. Like the other CB's, the CB400F probably had one and the same wiring harnass for different markets. Things that may differ, are: 1. US had position lights in the blinkers, Europe had not. 2. Europe had a position light in the headlamp, US did not. 3. Europe had a 'PA' switch to flash light signals, bringing the high beam filament on, even when the headlight was already on in lo beam. 3. US had an 'headlamp always on' arrangement (before the bloody thing had even started*), Europe did not, meaning it had a separate switch at the RH side on the handlebar for * P H (off, position light, headlight) and a separate selector switch for hi and lo at the LH side on the handlebar. 4. Switching the IGN key to P (Park) brings both the position light and the taillight on in Europe, in US, I believe the taillight only. The horn in Europe was wired differently. Honda made an exception to the rule black is switched power. As far as the horn, a short black wire goes to the frame and the light green brings power. I tell you all this, so you can understand why you find some wires ending 'blind'. As far as the blinkers, later models CB had the turn switch modified thus, that you could slide the switch halfway for temporarily blinking (as long as your thumb kept the switch there) or slide all the way, to have the blinkers stay on. In the latter mode it would sound the turn signal buzzer to remind you. Most owners I know, disconnected that childish and annoying buzzer.
Is your wiring diagram by Honda or from some aftermarket source? In case you've missed it, here's the addendum to the original Honda Shop Manual that deals with electricketry: https://www.classiccycles.org/media//DIR_1653304/DIR_1653404/DIR_1653504/d28e7d12b0a2c4d3ffff8757ffffe417.pdf
* Pressing the start switch would simultaneously kill the headlight.
« Last Edit: January 01, 2019, 08:17:19 AM by Deltarider »
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Offline bryanj

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Re: CB400F USA spec wiring diagram question
« Reply #2 on: January 01, 2019, 06:59:24 AM »
Indicators first, in th US you have twin fillament 21/5 watt bulbs, the 5 watt is on with ignition but goes out when the 21 watt is flashing. The indicator wires are blue and orange the running lights have a white stripe in the colour.

The P(F) stands for Pass(Flash) which operates the main beam when held in.

Not sure about the N but is common that when moving from dip to main, or vice versa, both are connected momentarily but there is normally no "definitive" position for this.
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

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Offline mattsz

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Re: CB400F USA spec wiring diagram question
« Reply #3 on: January 01, 2019, 08:19:55 AM »
Thanks for the informative replies, guys!

The diagram I am using, which I attached, appears to be by Honda.  It's in the shop manual for the CB350F - CB400F; this specific diagram is in the CB400F supplement.  This manual is available for download just about everywhere online.  Interestingly, while looking to confirm that information, I found that the manual gives some more details on the switches' operation, but the P(F) remains a mystery.

bryanj - with respect, are you sure about the P(F)?... I know the UK versions have a "flash-to-pass" feature, but in the UK spec diagram, it's labeled "PA," and there's a terminal shown in the diagram's switch, with a proper connection.  The US version, as far as I know, doesn't have the "flash-to-pass" feature, and my bike's original owners manual makes no mention of it.  The shop manual's details on the switch's workings show wire colors for each connection - except the P(F) one.  So it has no wire color associated with it, and it doesn't appear on the diagram.  Which still leaves me wondering, what the heck is it meant to be?  What am I missing?

As Deltarider says, just try it out... I'd like to, but my bike is in storage in a neighbor's garage with limited access, and with no power.  So that option is off the table for the moment...

Offline Don R

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Re: CB400F USA spec wiring diagram question
« Reply #4 on: January 01, 2019, 09:05:14 AM »
 These guys got it right, I'm sure they used the same harness with (some) different switches for different countries. In the wire pocket under your gas tank is the jumper that jumps out the Headlight switch wiring that would be there on a Japan or euro spec bike.
  I used a euro right control with an off/park/on headlight switch from DSS and a Marchal headlamp from Yamiya with the park light on my 75 cb400F. Once I finally figured it out, I just removed the jumper and connected the proper color wires. It's kind of cool with the LED amber park/running lamp in the headlight bucket. I had a blue LED in it but it was a little too blue and thought it might attract the local police. 
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Offline mattsz

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Re: CB400F USA spec wiring diagram question
« Reply #5 on: January 01, 2019, 09:11:27 AM »
These guys got it right, I'm sure they used the same harness with (some) different switches for different countries. In the wire pocket under your gas tank is the jumper that jumps out the Headlight switch wiring that would be there on a Japan or euro spec bike.
  I used a euro right control with an off/park/on headlight switch from DSS and a Marchal headlamp from Yamiya with the park light on my 75 cb400F. Once I finally figured it out, I just removed the jumper and connected the proper color wires. It's kind of cool with the LED amber park/running lamp in the headlight bucket. I had a blue LED in it but it was a little too blue and thought it might attract the local police.

Thanks Don - I've heard about the easy changeover to the right control with the light switch.  But, any ideas about the left control switches, and that P(F)?  The UK diagram, which includes the right-side light switching feature you describe, makes sense...

Offline Deltarider

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Re: CB400F USA spec wiring diagram question
« Reply #6 on: January 01, 2019, 09:32:17 AM »
Mattsz, I think I've found it. In the arrangement you see PL and PR, possibly meaning: position left and position right. Deducting P(f) would probably mean: position front and that explains why it is between arches, because your market did not have it, but the European did. I saw the corresponding brown wire in your diagram ending 'blind'...
BTW, do the CB400Fs really have a pointless regulator?
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Offline mattsz

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Re: CB400F USA spec wiring diagram question
« Reply #7 on: January 01, 2019, 10:10:37 AM »
Mattsz, I think I've found it. In the arrangement you see PL and PR, possibly meaning: position left and position right. Deducting P(f) would probably mean: position front and that explains why it is between arches, because your market did not have it, but the European did. I saw the corresponding brown wire in your diagram ending 'blind'...

Maybe... but it seems odd to note it in that way, when the euro (well, UK anyway, which is the other diagram I have) bikes' position light isn't switched by the left hand bar switches, and doesn't change regardless of what the main headlight beam or turn signals are doing - according to the diagram, the euro(UK) spec bike doesn't have a P(F) either.

The P(F) is listed on the grid along with all the other switch contacts, showing as connected with other switch contacts in various switch positions, yet it doesn't actually appear to exist on either diagram.

Quote
BTW, do the CB400Fs really have a pointless regulator?

Apparently.  Don't ask me what it's for...  ;)

Offline mattsz

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Re: CB400F USA spec wiring diagram question
« Reply #8 on: January 01, 2019, 10:12:43 AM »
By the way - I see that diagram, and the UK version, are both found in the Haynes manual.  I can't say for sure where they originated, though...

Offline Deltarider

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Re: CB400F USA spec wiring diagram question
« Reply #9 on: January 01, 2019, 10:35:50 AM »

Quote
BTW, do the CB400Fs really have a pointless regulator?

Apparently.  Don't ask me what it's for...  ;)
Reason I ask is that also in a CB550Fs wiring diagram (Shop Manual Honda CB500-CB550 p.169) I've seen a pointless regulator mentioned where I seem to remember all CB500/550s had the same oldstyle regulator. Forget it. Just curious. Oh, without going into detail, a regulator sees to it (by switching) that the alternator works just right, not too little, not too much.
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Offline bryanj

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Re: CB400F USA spec wiring diagram question
« Reply #10 on: January 01, 2019, 10:41:52 AM »
Having eventualy managed to enlarge the posted diagram i suspect that the P(f) is the Power in or (feed) but not 100% sure.
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline mattsz

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Re: CB400F USA spec wiring diagram question
« Reply #11 on: January 01, 2019, 10:42:58 AM »

Quote
BTW, do the CB400Fs really have a pointless regulator?

Apparently.  Don't ask me what it's for...  ;)
Reason I ask is that also in a CB550Fs wiring diagram (Shop Manual Honda CB500-CB550 p.169) I've seen a pointless regulator mentioned where I seem to remember all CB500/550s had the same oldstyle regulator. Forget it. Just curious. Oh, without going into detail, a regulator sees to it (by switching) that the alternator works just right, not too little, not too much.

Just a little joke - don't ask what it's for, as it's pointless...

Offline mattsz

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Re: CB400F USA spec wiring diagram question
« Reply #12 on: January 01, 2019, 10:47:02 AM »
Having eventualy managed to enlarge the posted diagram i suspect that the P(f) is the Power in or (feed) but not 100% sure.

Could be, but then the chart doesn't really make sense... I knew there was a reason I liked the UK spec better!

Offline bryanj

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Re: CB400F USA spec wiring diagram question
« Reply #13 on: January 01, 2019, 11:05:07 AM »
I think it may be just to understand the workings of the switch as there is no connection labled as feel from indicator relay plus where do the front running lights get power from? As i am in UK i have never had to figure it out as all the imports you have to disconnect the running lights as they are not legal here
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline mattsz

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Re: CB400F USA spec wiring diagram question
« Reply #14 on: January 01, 2019, 01:45:00 PM »
I think it may be just to understand the workings of the switch as there is no connection labled as feel from indicator relay plus where do the front running lights get power from? As i am in UK i have never had to figure it out as all the imports you have to disconnect the running lights as they are not legal here

bryanj - your first statement may be correct, although it's strange that just that one thing would be left out.  Not sure what you mean where I highlighted above - but now that I look closely, yes: where do the front running lights get power from?  Is there a mistake or omission in the diagram?  If we take the diagram's left-hand switch block at a truly isolated unit, then it appears the only source of power to the parking lights would be the HL terminal, which is fed by the black/yellow wire that powers the headlight.

This does nothing, however, to explain the headlight dimmer switch arrangement whereby the high beam position sees only the HL and Hi contacts closed, but the low beam position sees the HL and Lo and the P(F) contacts closed... and the middle (N) position, which doesn't even exist as far as I can tell, sees all four contacts closed - which would imply that both hi and low headlight filaments could be lit at the same time, something that I don't think can happen on this US spec circuit (but could with the UK "flash-to-pass" circuit).

Offline Bodi

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Re: CB400F USA spec wiring diagram question
« Reply #15 on: January 01, 2019, 04:08:18 PM »
I'm sorting through the factory wiring diagram (attached) for my bike (a '77), and I'm having trouble sorting out the switch contact grid in the lower left corner - there's contacts on this grid that aren't shown on the diagram's switches.  Can anyone help?

I understand the first section, the turn signals - only I assume that there's two each of L and R because there's a front and rear turn signal bulb - but why use L1, L2 and R1, R2 when there is only one L and one R contact on the switch?
This is to show there are two positions in the switch, L1/R1 momentary for lane changes (signals as long as you push the lever up to the detent but not onto it) and L2/R2 fully on for real turns, lever in the detent so it stays on until you switch it off.

The next section has me confused.  First of all, what is P(F)?  The diagram's switch block has no such contact.  As for the upper position light section, I suppose it's meant to show that when a turn signal is on, the position light for that side is extinguished?  Makes sense, but again, why have two left and two right connections when there's only one switch contact, and in fact only one position light, for each side?
L and R are the wires to the signal lamps, each goes to both front and rear. P(f) is a connection inside the switch so it doesn't get a terminal or wire color. P(f) gets power for the front markers from the dimmer switch when the headlight is in low beam (or "N" although that is just there to illustrate that the headlight switch is make-before-break, so the headlight does not go off when switching low/high beam). Then P(f) goes over to the turn signal switch to shut off the marker (on PL or PR) on a flashing side.

For the sake of argument, in actual function can the L1-L2 and R1-R2 blocks on the chart be condensed simply to L and R?
as explained above L1 & L2 are switch positions, not wires or connections.

I get the horn section (  )...

The lower headlight dimmer section also has me scratching my head... again, I wonder about that P(F) contact, but also, what's with the (N) switch position, which shows the high and low beam connected simultaneously?  My bike's switch doesn't have a middle "N" position, just Hi and Lo, with no selection between them.
Again, explained above - the N is just a point in the lever movement where both lamps are on, there is no detent and it's not entirely easy to get the switch to sit there if you really want all the front lighting on (and it would probably cause battery discharge as the alternator is not overly strong).

The Honda diagrams are unlike almost any other circuit diagram style I've seen but once you get the concept they are pretty easy to comprehend. Doing it this way simplifies the wiring drawing since most of the switch contacts are not shown there.

The part that puzzled me longest is the parking lamp wiring, finally I figured out that it switches which fuse powers the tail light.
And... the magic jumper that changes a black wire to brown/blue... you super need this to get the headlight on if you don't have a lights on/off switch (like the USA, Canada, etc.).
« Last Edit: January 02, 2019, 05:35:20 AM by Bodi »

Offline Deltarider

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Re: CB400F USA spec wiring diagram question
« Reply #16 on: January 02, 2019, 01:29:20 AM »
So... if there wasn't a turn signal buzzer on the CB400F, what is that little unnamed thinghy doing up there, the one with the brown/blue wire to it, not that far from the upper left corner? Did it only exist on the drawing board and did it never materialise in the real world?
What could the 'f' mean in P(f)? Facultative? Or were the Japanese designers so fed up with these silly US gadget demands giving them a headache, that they expressed their annoyance - and careful as they are - with just a hint to the 'f' word, in other words: is there any humour in the Honda wiring diagrams? Man, this new year has just started and I need aspirin already...
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Offline Bodi

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Re: CB400F USA spec wiring diagram question
« Reply #17 on: January 02, 2019, 05:40:17 AM »
"what is that little unnamed thinghy doing up there, the one with the brown/blue wire to it"
That is the lighting power jumper that replaces the lighting switch - I called it a brown wire (corrected). Note that no replacement switchpod comes with this jumper now, it's stuck in with the pod wires' cable sleeving on original bikes but it falls out easily.

Offline mattsz

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Re: CB400F USA spec wiring diagram question
« Reply #18 on: January 02, 2019, 05:42:56 AM »
"what is that little unnamed thinghy doing up there, the one with the brown/blue wire to it"
That is the lighting power jumper that replaces the lighting switch - I called it a brown wire (corrected). Note that no replacement switchpod comes with this jumper now, it's stuck in with the pod wires' cable sleeving on original bikes but it falls out easily.

Yup.  I was writing as Bodi posted:

The "little unnamed thingy" was mentioned by Don R - it's a connecting jumper used on the bikes like the US one on which the headlight is always on, and therefore have no lighting switch on the right handlebar control.  Here's a detail of the UK spec diagram, you can see the brown/blue and black wires connect at the switch instead:


Offline mattsz

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Re: CB400F USA spec wiring diagram question
« Reply #19 on: January 02, 2019, 05:45:11 AM »
What could the 'f' mean in P(f)? Facultative? Or were the Japanese designers so fed up with these silly US gadget demands giving them a headache, that they expressed their annoyance - and careful as they are - with just a hint to the 'f' word, in other words: is there any humour in the Honda wiring diagrams? Man, this new year has just started and I need aspirin already...

I toyed with the thought that the P(F) implied "fused" power, but that doesn't really make sense either.  Why doesn't the UK spec diagram use it?  Something is missing...

Offline bryanj

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Re: CB400F USA spec wiring diagram question
« Reply #20 on: January 02, 2019, 06:04:06 AM »
Because the UK did not have running lights
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Offline mattsz

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Re: CB400F USA spec wiring diagram question
« Reply #21 on: January 02, 2019, 06:09:47 AM »
This is to show there are two positions in the switch, L1/R1 momentary for lane changes (signals as long as you push the lever up to the detent but not onto it) and L2/R2 fully on for real turns, lever in the detent so it stays on until you switch it off.

That makes as much sense as anything, although the UK owners manual also touts that feature, yet the UK wiring diagram's switch grid doesn't differentiate.  Wonder why they chose to do it differently?

Quote
L and R are the wires to the signal lamps, each goes to both front and rear. P(f) is a connection inside the switch so it doesn't get a terminal or wire color. P(f) gets power for the front markers from the dimmer switch when the headlight is in low beam (or "N" although that is just there to illustrate that the headlight switch is make-before-break, so the headlight does not go off when switching low/high beam). Then P(f) goes over to the turn signal switch to shut off the marker (on PL or PR) on a flashing side.

If that's so, strange that it would be omitted.  So P(F) gets power from the black/yellow - fed HL connection inside the switch?  It's the only place, as far as I can see, that steady power could come from for the position lights...

Quote
The Honda diagrams are unlike almost any other circuit diagram style I've seen but once you get the concept they are pretty easy to comprehend. Doing it this way simplifies the wiring drawing since most of the switch contacts are not shown there.

Do you mean that the drawing is simplified since the switch connections aren't shown?  As I see it, all of the switch contacts are shown,with the glaring exception of the P(F).

I agree that they are pretty easy to comprehend once you get the hang of it - actually, the service manual for my Kawasaki W650 has a very similar style and layout, so I had no trouble with the Honda one... until I came across, so to speak, that missing P(F) contact. 

Offline mattsz

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Re: CB400F USA spec wiring diagram question
« Reply #22 on: January 02, 2019, 06:18:03 AM »
I toyed with the thought that the P(F) implied "fused" power, but that doesn't really make sense either.  Why doesn't the UK spec diagram use it?  Something is missing...

Because the UK did not have running lights

I guess what I meant was, if P(F) implied "fused" power, which the UK bikes also have, why not use that nomenclature in both diagrams?

The diagram calls them "position lights" and they're in the front only; maybe P(F) means "Position (Front)"?  I really don't know.

I could probably answer these questions for myself if I could get at the bike with some tools and a meter, but I can't... so I'm killing time hoping someone who has dug into this before might know...

Offline Bodi

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Re: CB400F USA spec wiring diagram question
« Reply #23 on: January 02, 2019, 07:41:39 AM »
"Do you mean that the drawing is simplified since the switch connections aren't shown?"
No, I meant the contacts: these are not in the main line drawing, they're shown in those switch function blocks. Schematics for electronic equipment normally show the switch contacts in the connection line drawing, making it somewhat easier to follow but also making the lines even more complicated with more crossovers to get to the correct switch terminals. The 400 wiring diagram is already confusing, following a given wire through the crossovers is not always easy - particularly on the tiny version in the owners booklet.
Complex switchgear like the keyswitch or pod switches would be less understandable if included in the main circuitry line drawing... if that's even possible.

Offline mattsz

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Re: CB400F USA spec wiring diagram question
« Reply #24 on: January 02, 2019, 08:05:02 AM »
Maybe it's a question of semantics... I consider the little dots inside the blocks representing the switches in the diagram itself (not the grid at the bottom) as contact points - they've got colored wires attached. I suppose it could be argued that those dots actually represent the points where the wires are soldered to the switch, and inside the body of the switch there are metal strips which actually connect together to complete a circuit.  But the goal here is to provide an understandable representation of what's happening - and the grid at the bottom should fulfill that role.

Consider as an example the "Headlight Dimmer - Turn Signal - Horn Switch" at the lower left, which has only a row of what I'm calling contacts.  Compare that to the "Engine Stop - Starter Switch" at the upper left - this one isn't just a block with a row of contacts, it shows the switch connections.  It's a simple configuration, so it's easy to represent it this way in the diagram itself.

To my mind, the failure of this diagram is the omission of P(F), and the crucial information about how it interacts with wherever its power is coming from...