Article [13] ST1300 - Headlight Circuit

[jfheath]

A Circuit Diagram showing the odd configuration of the ST1300 headlights, with some explanation.
The circuit is taken from a UK 2009 ABS model - from 2004 headlamps are on all of the time, there is no light switch on the handlebar console.
However, the UK spec models have a 'pass' switch to flash the main beam. USA vehicles and various others do not have this part of the circuit.

Contrary to what I believe to be common practice, the twin headlights on the ST1300 are not operated by relays in the conventional manner.
Instead, the circuit draws power from three different fused circuits.

• The right hand headlamp is powered directly from one fuse, passing through the beam dip switch for high and low beam.
• The left hand headlamp draws power from a different fuse. The left handlamp beams are switched by two relays - one for high beam, one for low beam. The relays are triggered by the power feeds to the right headlamps.
• The Pass switch feeds into the right hand headlamp circuit from a third fuse. This bypasses the light switch if there is one, and also bypasses the cutout switch at the starter motor button, which normally cuts power to the headlights when the start motor is activated.

The Diagram is shown below.

I should add that the earth for the relays and the bulbs are shown separately - just to keep the diagram tidy. In fact they are all wired to a ground point, but they do not necessarily take the same route.

Edit 22 Aug 23: The relay grounds go through the yellow, multiway ground connector near the right hand mirror fixing bracket, behind the headlight. The headlight grounds do not.

The diagram for my 2009 model shows that the relay grounds are all connected at a Pink 20P connector, not the yellow. The headlights ground passes through the white 24P multi-way connector. Both use green cables, both earth at the main earth point on the frame under the rear of the fuel tank. ​

Diagrams for pre-2008 models suggest that there is no connector joining the green earth leads - earths are just spliced into the harness. I don't believe that this is correct though.​

The realities are therefore still a mystery to me for other models.​

There are a couple of errors in my copy of the 2004 Uk Honda circuit diagram. The hi and low beam filaments are drawn incorrectly, and the left and right relays are incorrectly labelled. As a result, following any single circuit, eg the Blue wire for the right hand main beam makes very little sense. Maybe later editions of the manual do not have this oddity, but my bike matches the two excellent coloured circuit diagrams available on ST-Owners. And the diagram above is correct for my Uk St1300A9.

The passing switch is an integral part of the Hi/Lo beam rocker type switch. However, none of the on-line coloured diagrams that I have seen show how this is wired. The diagrams in my Honda Workshop Manual show it, but there are so many errors on that, it is difficult to know what is right and what is wrong. The above diagram corrects an error in the official diagram in the cable colour for the hi beam passing switch.

For high beam, the switch is rocked forward from the low beam position, and for passing it is pressed back against a spring from the dipped position. Pressing pass keeps the low beam filaments turned on, and additionally injects power from a 3rd fuse - the one labelled Pass, Horn, Stop - to the Right hand Hi Beam circuit - which in turn triggers relays for the left hand main beam. As a result, when the lights are on, the passing switch causes both filaments to be turned on in both bulbs. There are two fuses for the headlights - 1 for the right hand bulb, one for the left hand bulb. When the passing switch is pressed the low beam is already drawing 55w and then the main beam draws 60w. So the LH headlight fuse is supplying power for both filaments and is almost at capacity when the passing switch is pressed. The right hand bulb is getting its power from two different sources when the passing switch is pressed.

The reason for doing this was that I was trying to establish the current drain on each of the fuses. I was particularly concerned with fuse C (abs model) because it feeds into the accessory quartet harness, and may limit the available power. See this thread for that information (post #6).

Just for interest - this is a table of which parts of the headlight circuit are active when different combinations of the 3 fuses are inserted and removed.



For completeness here are links to the coloured circuit diagrams - both of which show the correct wiring and labelling for the headlight circuit, but neither show how the pass button is wired.

@Anna'sDad - Rev 7 - (3) Article [13] - ST1300 - Wiring Schematic | ST1300 Articles | ST-Owners.com (st-owners.com)

Excellent schematic, easy to follow. Some labels difficult to read. I use this one most of the time.

@SpikingJC - 7 Diagrams - (3) Article [13] - ST1300 - Wiring Schematics for 03-07 Standard | ST1300 Articles | ST-Owners.com (st-owners.com)

Different diagrams for different years and models. These use dotted lines to represent the two-coloured wires and I find them less easy to follow a single cable. But the layout makes it easier to locate individual components - the diagram shows the components closer to the location on the bike, the labels are easier to read when zoomed in, and the diagrams show the location in the circuit of the multiway earth connectors - which are not shown on the Honda wiring diagrams that I have (A3/A4). I use this to confirm what I understood from AnnasDads diagram !

 

[Larry Fine]

It was common for years for European cars to have the lighting divided between left- and right-side circuits.

Maybe this has something to do with it, or minimizing the risk of losing all lighting from a relay failure.

 

[Sadlsor]

I have wished since I first got this bike, for a "passing" button or switch near my left index finger.
No doubt, some devoted and determined electrical mastermind could fabricate one relatively easily, but that's outside my wheelhouse, and not that great a requirement.
I imagine a re-release of the ST-bike (not likely to happen) today, would have one.

 

[ad.hom]

"passing" button or switch near my left index finger.

While I've ridden bikes that had a "PASS" switch on the index finger (the Suzuki layout, if memory serves), horses for courses. I much prefer it on the thumb, and often ride with my thumb on the small strip of plastic between the ST13 "PASS" switch and the horn for easy access of either.

John, excellent diagram, as always. As far as I recall from resolving my ground issues on this circuit, the diagram matches my A2 as well (but there is a significant chance that there's differences that I simply don't remember).

 

[jfheath]

Thanks @ad.hom. From what I can see, the big difference is between the abs version and the standard version. Less wiring on the standard, and fuse boxes are different. I suspect the diagram will be the same, but maybe wire colours are different.

I have the Honda circuit diagram, but when I got into it and checked against my current A9, there are some discrepancies - eg bulb is shown wired incorrectly for Hi and Lo filaments, relay labelling seems transposed or wire colours are confused between Hi and lo circuits.

I tried to follow the curcuit through but encountered similar issues, and with no bike to compare it with, I cannot ensure that I create a correct diagram.

As for the pass on the finger of the 1100 - I never used it. Kept forgetting it was there. I believe the police ST1100 dispensed with this function and used it as a push-to-talk.

 

[CYYJ]

I have wished since I first got this bike, for a "passing" button or switch near my left index finger.

Just tap the starter button (on the North American spec 1300s) - that has more or less the same effect as the 'flash to pass' button on the European spec bikes.

When you tap the starter button when the engine is running, the starter does not engage, but the headlights extinguish.

Michael

 

[jfheath]

Thanks Michael

Ditto with the later spec (around 2006 on) European bikes - they have to have the lights on all of the time - European law - so the H/L cut switch on the starter push button has that same effect. I included that in the circuit diagram, but neglected to describe that aspect of the circuit.

It certainly saves worrying about the power demand on the battery / accessory fuse.
!! It is also much politer at night. I never understood why people like to say 'thankyou' (say if you stop to let them through a narrow section of road at night) by flashing 120W of intense blue-white light straight into your eyes.

Of course, the Pass switch illuminates the main beams whether the lights are turned on or off - for the models that have the luxury of turning the lights off.

 

[TourNut]

I ran across this bizarre headlight bulb powering when I installed a Kriss headlamp modulator - initially it created some very bizarre results , > ( one bulb bright , the other bulb barely lit at all , When I turned off the ST , this headlight situation would NOT turn off until I disconnected the battery ! ) > totally unacceptable .
I had the same model of Kriss modulator on my '91 GoldWing and it worked just fine on that bike . I compared the wiring diagram between the two bikes and discovered the ST's bizarre wiring - one bulb's current totally going thru the dimmer switch ; And the other bulb's current being fed by power relays like you would normally do & like the GoldWing has , on both bulbs . I rewired the ST to the same as the Goldwing's circuit & the modulator then worked as required , and cut the current way down - going through the dimmer switch contacts & circuit . ( I added some heavy duty , high end NAPA relays to do it , left the OEM circuit intact - it now only turns on the low current high beam indicator light in the dash & my new relays )
Since , I have wondered , in an otherwise great Honda MC design , WHERE did that bit of insanity come from , with that headlight wiring , when they already had done it correct from many previous models ? !

 

[Catmandu2]

Without remembering all the details of my headlight work on my ST13,, CB1000c and CB900c,,, this does remind me of a couple of points experienced. Voltage is a bit higher on the LH headlight circuit of the ST13,,, which is why in a bike using dual H4's,, the LH bulb usually gives up first. Same is even more true for my buddies bmw R1200rt,,, which blows the LH bulb annually. The modulators I have installed, always are specified that they be powered through the LH circuit only. When I made up my last plug 'n play harness, to install the Kisan modulator on my ST13,,, there was an error identified in the oem wiring schematic. The corrections were nicely documented on this site, in earlier posts,,, which allowed me to complete my harness and installation. Cheers,, CAt'

 

[Sadlsor]

Good stuff, Catmandu2!
The Kisan headlight modulator is on my list of things to add.
I've installed it on previous bikes, and cannot remember a single downside to the addition.
Which reminds me... I need to revise my signature now that I'm steadily completing my wish-list for farkles.

 

[ST Gui]

I much prefer it on the thumb

This would be my preference. Alas I don't have the wherewithal to incorporate the appropriate switch pod to facilitate that.

 

[Larry Fine]

Related question (I hope): Looking through the wiring diagrams in my Clymer, I see that any ST1100 that has a hi-beam flasher button also does not have turn-signal contacts for running lights (no dual-filament turn-signal bulbs).

Does the same hold true for the ST1300? Do only non-US-spec bikes have the flash button? Any model that has both running lights and a hi-beam flasher? Any model with extra left switch-pod switches? Perhaps a police version?

 

[jfheath]

The Uk spec ST1300s have a low wattage bulb in the top left and top right of the headlamp lens. There is no second connector to the mirror housing lens, although the indicator bulb holder will accept a two filament bulb, like the tail/stop bulb at the rear, it is not wired.

 

[Andrew Shadow]

Hi John;

I am always impressed by your diagrams. They are always very well done. Having limited experience with CAD software, I can appreciate the time and effort that you must put into them.
What computer software are you using to create wiring diagrams such as the one in post # 1 above?

 

[jfheath]

Thanks Andrew

The answer is vector drawing package called DrawPlus x8 from Serif. It is no longer in production, but a free starter edition of an earlier version which Serif used to make freely available, is still hanging around on some free download sites. eg cnet.

I've sent a PM with more details ! Nothing illegal here - it was published free of charge by Serif and can be found if you know where to look - but Serif have now moved on to another range of software and no longer support their legacy products.

 

[ST Gui]

it was published free of charge by Serif and can be found if you know where to look

I'd track that down if I was on a platform that supported it. But alas... However you make excellent used of it.

 

[jfheath]

I'd track that down if I was on a platform that supported it. But alas... However you make excellent used of it.

Kind of you to say that - thank you.

They have brought out a new improved version which is available as a free one week download. I downloaded it yesterday, so I am not sure if it actually does the same stuff as DrawPlus, or if it has become too complex for what I want. I intend to try it out though. It is called Affinity Designer - still by Serif, and reasonably priced. But it comes in versions for PC, Mac and Ipad apparently

 

[Andrew Shadow]

I had been totally confused by John's question in another post where he stated that fuse C played a role in the operation of the ST1300 headlamp circuit but he did not know how. He asked how fuse C (on an ABS model) connected to the headlamp circuit. Looking at my Honda shop manual, I could find no such connection. I didn't respond in that thread saying so because I know how thorough John is in his research and thought that I must be missing something. It was bugging me however. I wanted to know why I couldn't see the link to fuse C no matter how many times I looked at the wiring diagram.

John and I have exchanged a couple of PM's and I believe that I understand now. I had never scrutinized the Honda shop manual wiring diagrams very closely before now because I never needed to. Based on comparing what John sent to me with the wiring diagram in my Honda shop manual (2003 through 2013 version), I now realize that Honda issues different shop manuals in different regions of the world. I knew that they issued them in different languages but I was not aware that the technical content of the manual also changed based on the market it was intended for. I just assumed that they all had the same technical content. In the case of the wiring diagrams, I thought that they were all the same and if a particular option was not present on your particular bike you just ignored that component in the wiring diagram. This would not seem to be the case.

Relative to this headlamp circuit wiring diagram, the North American ST1300's do not have the feature allowing the driver to flash the headlights- referred to as the flash-to-pass switch. Consequently, the ST1300 shop manuals sold in North America do not illustrate the wiring of this switch on the wiring diagrams- at least mine purchased through Honda Canada does not. It makes reference to the pass switch but does not show how it is wired in to the bike. This is why I could not find a link between the headlamp circuit and fuse C. Fuse C is used to power this flash-to-pass feature. If the bike does not have the flash-to-pass feature, fuse C does not seem to play any role in the headlamp circuit. If I am still getting this wrong, someone please let me know.

I bring this up as a heads up to anyone trying to trouble shoot a problem on their ST1300. I have no idea how many other things in the manual are affected by regional differences. Overwhelmingly this will not be an issue. It will only become a problem when an unusual and uncommon problem is being diagnosed and where a minor difference between the manual and the model of ST1300 being diagnosed could completely throw your trouble-shooting off. It is under these circumstances that a minor difference can have a huge impact on whether someone proceeds rightly or wrongly in their trouble-shooting. A lot of us purchase used items from other members all over the world including shop manuals. If your diagnosis is giving results that don't seem to make sense to you, it might be worth taking a moment to confirm that the version of the shop manual that you are using is actually relevant to and intended for your particular model of ST1300.

Attached is what I believe to be is a correct wiring diagram of a North American ST1300 headlamp circuit. It was downloaded from somewhere on this site but I do not know who produced it.
I have not verified any of this against my 2009 ST1300 because it is put away and asleep for the winter. If anyone knows that any of the above is incorrect please correct it.

 

[Larry Fine]

I haven't looked closely to 1300 wiring, but on the 1100, the US-spec bikes have running lights in the dual-filament front signals, but no flash switch, while the non-US-spec bikes have the flash switch and single-filament front signals, plus separate position lights.

 

[jfheath]

Thanks @Andrew Shadow and @Larry Fine . This seems so long ago now - just reading some old threads, waiting for the Covid Paint to Dry before I can go out riding.

Just so we are clear for any others looking in at a later date. The flash-to-pass switch on the UK bike is not a separate switch - like it is on (say) the 1100, where a completely separate sprung loaded switch is placed where it can be easily squeezed by the index finger. On the UK ST1300 it is an integral part of the high/low beam rocker switch - which basically has 3 positions:
Hi beam, rocked forwards
Lo Beam, rocked backwards
Flash/Pass - press backwards against a spring from Lo Beam position.

Here is the relavant info from the USA model handbook



And below, from the UK handbook




And the almost invisible give-away label on the button.



From Andrew's wiring diagram it seems that the two models (USA and UK) are wired in a broadly similar way, so injection of 12v into the high beam filament on the right hand bulb from a source that has the capacity for to power just one bulb @ 60w/5amps (ish), will turn on both main beams, in addition to the low beams already illuminated.