Topic: CB400F USA spec wiring diagram question

[Deltarider]

Yeah, what we need is updated interactive wiring diagrams (like Old Man Honda) for all models. Would be nice to be able to ask: "OK, forum, show me how the position lights and indicators are wired on the Honda CB400F2" and that your smartphone/tablet/laptop would show it blinking and all.
Are we sure the CB400F nowhere had the turn signal buzzer? The wire happens to be the appropiate color...
Maybe the Honda designers intended to fit one, but changed their mind when they were briefed that everybody hated the bloody thing and so decided to do something else with that br/b wire.

[mattsz]

Yeah, what we need is updated interactive wiring diagrams (like Old Man Honda) for all models. Would be nice to be able to ask: "OK, forum, show me how the position lights and indicators are wired on the Honda CB400F2" and that your smartphone/tablet/laptop would show it blinking and all.
Are we sure the CB400F nowhere had the turn signal buzzer? The wire happens to be the appropiate color...
Maybe the Honda designers intended to fit one, but changed their mind when they were briefed that everybody hated the bloody thing and so decided to do something else with that br/b wire.

Well, that's kind of what I'm working on - not an interactive diagram, but an easy-to read color duplicate of the complete diagram, along with smaller diagrams showing only certain specific circuits.  Just for my own use, and interest - but if it turns out well and other people like it, they're welcome to it as well.  Just what the world needs, another colorized diagram, huh? 

Not sure what is the "buzzer" of which you speak, but I've never heard of it on the CB400F.  The wire in question is clearly meant to provide power to the headlight - either through a switch, as on the UK units, or via a direct connection, as on the US units...

[Deltarider]

Well, what do you know... Had a look at the Owner's Manuals CB400F, that are listed under Download Motorcycle Manuals (above). On p. 20 the buzzer function is mentioned, but so far I have not spotted it in the wiring diagrams. http://forums.sohc4.net/index.php/topic,17788.0.html Looks like Honda did change their mind.
BTW, I applaud your initiative.

[mattsz]

Well, what do you know... Had a look at the Owner's Manuals CB400F, that are listed under Download Motorcycle Manuals (above). On p. 20 the buzzer function is mentioned, but so far I have not spotted it in the wiring diagrams. http://forums.sohc4.net/index.php/topic,17788.0.html Looks like Honda did change their mind.
BTW, I applaud your initiative.

You're right!  But in the original print owners manual, which I have, it doesn't mention the buzzer - maybe it's another feature included in the non-US model...

[mattsz]

While we're at it... can we discuss the dotted lines that trace around the diagram?

As I understand it, the one that encloses most of the center wire section (and that little tail light power wire jumper) simply represents the main harness, that everything else connects to?

What's the deal with the additional dotted line surrounding the red wire that runs between the starter solenoid and the main fuse, and the red/white wire that runs between the starter solenoid and the (lower left) rectifier? EDIT: And, also the short section of the green wire that leads to the frame ground up at the top...

[Bodi]

"Are we sure the CB400F nowhere had the turn signal buzzer? The wire happens to be the appropriate color"
What wire? There is no buzzer on a 400F, I'm pretty sure of that. Where do these things connect, anyway? You either need a separate contact in the signal switch or diodes from the signal lamp wires. I haven't seen any switchpods with extra wires but have only seen US/Canada models and some domestic Japan ones.

"can we discuss the dotted lines that trace around the diagram"
The main harness has a dotted line around it. All unfused battery power wires have an extra insulating sleeve, those dotted lines either indicate the extra protective sleeve or that it's unfused power. Note sure about the green.
The rectifier is not "pointless" on any 400 I've seen, I guess that was a design idea that got changed. And I think the fuseblock power connects directly to the battery "+" terminal not the starter relay.

[mattsz]

"Are we sure the CB400F nowhere had the turn signal buzzer? The wire happens to be the appropriate color"
What wire? There is no buzzer on a 400F, I'm pretty sure of that. Where do these things connect, anyway? You either need a separate contact in the signal switch or diodes from the signal lamp wires. I haven't seen any switchpods with extra wires but have only seen US/Canada models and some domestic Japan ones.

As he says, there is a version of the owners manual which says there is one - but that's all I know about that.

"can we discuss the dotted lines that trace around the diagram"
The main harness has a dotted line around it. All unfused battery power wires have an extra insulating sleeve, those dotted lines either indicate the extra protective sleeve or that it's unfused power. Note sure about the green.
The rectifier is not "pointless" on any 400 I've seen, I guess that was a design idea that got changed. And I think the fuseblock power connects directly to the battery "+" terminal not the starter relay.

Those are unfused wires, you could be right about the extra dotted lines.

What is a "pointless" regulator (not rectifier) anyway?  What does that mean, and why are there two? (two shown in the diagram, anyway - are there two on the bike?)

[Deltarider]

Bodi, like on the other CB's the fuseblock is supposed to connect to the solenoid and not to the battery. It makes sense: you want to have that wire as short as possible to reduce the risk of chafing and consequently shorting which would bring a serious problem... A brown/blue wire on other models CB, including my CB500K2 (ED) is reserved for the turn signal buzzer. That's why I assumed the CB400F would probably have something similar. Like many others I disconnected the annoying buzzer. Then I had it wired for some years in parallel with the oil warning lamp to serve as an acoustic alarm. When I got annoyed by that too, I disconnected it again. IMO it is best to make it useful as a 'sidestand out warner' but you need a mechanical switch for it (something like a brakelight switch). Matessz, if you're not familiar with the charging system and are interested, you could start with reading what is in the original Honda Shop Manual (see reply #1) or the Honda Motorcycle Electrical Systems that you find listed in 'Download Motorcycle Manuals' (above). I'm sure you will also find educational vids in Youtube on the matter. If you invest some time, you'll find that the electricals is about the simplest aspect of your bike.
About the silicon rectifiers. The one in the bottom is named correctly. It changes the AC generated by the alternator in DC. The one in the top should be renamed DIODE. It is part of a safety concept that prevents you accidentely starting the engine when in gear unless the clutch lever is pulled. If the diode would not be there, you would see the neutral lamp come on, whenever you pull the clutch lever and so would give you false information.

[mattsz]

Bodi, like on the other CB's the fuseblock is supposed to connect to the solenoid and not to the battery. It makes sense: you want to have that wire as short as possible to reduce the risk of chafing and consequently shorting which would bring a serious problem... A brown/blue wire on other models CB, including my CB500K2 (ED) is reserved for the turn signal buzzer. That's why I assumed the CB400F would probably have something similar. Like many others I disconnected the annoying buzzer. Then I had it wired for some years in parallel with the oil warning lamp to serve as an acoustic alarm. When I got annoyed by that too, I disconnected it again. IMO it is best to make it useful as a 'sidestand out warner' but you need a mechanical switch for it (something like a brakelight switch).

Surprising that they'd use a particular wire color for different purposes on different models made around the same time, but I suppose I've seen stranger things and nothing would surprise me...

Matessz, if you're not familiar with the charging system and are interested, you could start with reading what is in the original Honda Shop Manual (see reply #1) or the Honda Motorcycle Electrical Systems that you find listed in 'Download Motorcycle Manuals' (above). I'm sure you will also find educational vids in Youtube on the matter. If you invest some time, you'll find that the electricals is about the simplest aspect of your bike.

I have both of those downloads, but I haven't read through them in detail.  I do have a basic understanding about most of this already - I know what a rectifier and regulator do, I know how the alternator generates electricity, and I can generally follow a wiring diagram.  But I'll investigate, as I'm relatively new to motorcycling and I'm interested in how these things might have been adapted specifically for their use...

About the silicon rectifiers. The one in the bottom is named correctly. It changes the AC generated by the alternator in DC. The one in the top should be renamed DIODE. It is part of a safety concept that prevents you accidentely starting the engine when in gear unless the clutch lever is pulled. If the diode would not be there, you would see the neutral lamp come on, whenever you pull the clutch lever and so would give you false information.

You're right - the one attached to the neutral switch isn't really functioning as a proper rectifier; it's just a diode, and in fact is pictured as such...

[mattsz]

A little FYI regarding the turn signal buzzer - the Haynes book which covers the "400 and 550 fours - 1973 on" has this to say:

"On the CB550F model an audible indicator warning is also fitted.  This is mounted on the left-hand fork cover."

There are wiring diagrams for both the CB550 and the CB550F; both show a buzzer - fed by a Brown/Blue wire...

[mattsz]

First little discrepancy I found today... the powered wires between the rear turn signal housings and their nearest connectors (in a bundle on top of the rear fender) aren't colored orange and light blue as on the diagram - they're both plain ol' black, but each one has a little appropriately colored ring wrapped around the wire next to the connector.  Do you suppose it came from the factory this way?

[Deltarider]

I doubt it. Are the blinkers the originals or aftermarket?

[mattsz]

I doubt it. Are the blinkers the originals or aftermarket?

I think they're original - the housings match the front dual-filament fixtures, and they're all four the larger size that came on the USA '77 models.

Two of the front:






Rears:




And a closeup of the sorry sagging left side:

[bryanj]

Yes the indicators in the crate had black wires with coloured rings. It was quite funny to find them with the coloured rings taken off where it had been built from crate by somebody not used to doing Hondas.

[mattsz]

Here's a little something I found regarding the front position lights and where they get their power...

I took a run through the long list of manuals and documents here on the forum, searching for a wiring diagram of any Honda bike around 1977, hoping to find a similar arrangement to give me some clues.  I found two of interest.

The 750F models which run front position lights have a different setup, it's clear from the diagrams that they get power from the tail light wire.

However, the diagram for the '76 CB500T, despite representing only a 2 cylinder bike, shows a very similar wiring schematic, including the P(f) power source.  From the detail (first attachment below), it's clear in the diagram switch block that P(f) gets power directly from the low beam headlight source.  The connection grid suggests the same, and indicates that when the high beam is switched on, the front position lights go out, as well as having the right or left position light extinguish whenever its associated turn signal is selected.

The second attachment below shows a similar detail area of the CB400F diagram - the connection grid shows the same function, including that pesky P(f).  But as you can see in the diagram switch block... no P(f).  I wonder if this is an oversight, and my bike also gets position light power from the headlight low beam's white wire?

I haven't been able to check this on the bike yet, but I'm hopeful that the '77 400F matches the '76 500T in this regard, and that the mystery will be solved!

(Note: after staring at that 400F diagram for hours, and even redrawing it, I only just now noticed what I believe to be a minor error: the position lights' labeling could be considered backwards.  In the diagram switch body, the orange/white should be labeled PL and the light blue/white wire should be PR.  Compounding the error in the connection grid, the turn signal connections should be PL when Left is selected, and PR when Right is selected.  As it is, it does work as labeled, but if the PL and PR stand for left and right position light wiring, then it's backwards.  Semantics?)

Any thoughts?

[mattsz]

Pulled the white and orange/white wires from the harness to isolate them and clipped them to my continuity tester; with turn signal switch in "neutral" or "right," it shows shorted (beeps).  When I switch to "left," it shows open (no beep).

Promising...

[bryanj]

Little Japanese man was tired when he wrote it and/or the translater is too literal.

[mattsz]

I concluded the recent post about my white wire, low-headlight-beam power supplying the front position lights investigation with, "Any thoughts?"

Well, I have one: I was re-reading earlier posts on this thread, and waaaaay back on January 1st (seems like ages ago!), Bodi wrote:

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.

At that point I accepted that it could have been the case, but found it odd the wiring diagram would omit it.  I continued to speculate other possibilities; Bodi never came back and said, "No, Matt, I'm right.  Stop speculating."  Seems he was likely right all along... but I'd still like to get it confirmed before I add it to my diagram...

[Bodi]

It is not omitted. It's clearly shown in the switch block, in the headlight switch.

[mattsz]

It is not omitted. It's clearly shown in the switch block, in the headlight switch.

By "switch block," do you mean the switch arrangement grid at the bottom?  It's true the connection is shown there in both examples, but I didn't find it clear at all, as the connection is shown up in the body of the CB500 diagram, but is not shown in the body of the CB400 diagram- hence my use of "omitted"...

[Bodi]

The diagrams pictured are slightly different in that the 500T one (redundantly) shows the wire colors on the switch block, and has a crossed out box where the  P(f) wire color would be... if that wire existed. The switch block is shown exactly the same way, the 500T disconnects the marker lights in "N" though. The switching for P(f) is shown exactly the same way in both drawings. What's missing?

[mattsz]

The diagrams pictured are slightly different in that the 500T one (redundantly) shows the wire colors on the switch block, and has a crossed out box where the  P(f) wire color would be... if that wire existed. The switch block is shown exactly the same way, the 500T disconnects the marker lights in "N" though. The switching for P(f) is shown exactly the same way in both drawings. What's missing?

The 500T diagram - P(f) shown (red arrow):





The 400F diagram - one fewer connections, no P(f):





I'd call that missing...

[mattsz]

Yes the indicators in the crate had black wires with coloured rings. It was quite funny to find them with the coloured rings taken off where it had been built from crate by somebody not used to doing Hondas.

bryanj, do you know if providing black wires with colored rings was a random thing, or was it common?

[bryanj]

It was normal when i was working on Hondas back in the 70's, front as well but remember UK only had 1 wire front indicators.

[mattsz]

It was normal when i was working on Hondas back in the 70's, front as well but remember UK only had 1 wire front indicators.

The front turn signal/position light fixtures have two wires, of course - on my bike they're both black, with a plain orange or light blue ring on the turn signal wires, and orange/white or light blue/white ring for the position light wires.  Three of those four are visible in the attached photo of my headlight bucket...