Bonneville America Forums Forums Technical Forums General Tech Modified Headlight Cut

This is for bikes without a headlight control switch (like the EFI bikes) - this fairly simple mod will keep the lights off completely until after it is started.*

Even if you incorporate the starter relay bypass mod - http://www.bonnevilleamerica.com/forums/...ge=3#Post500861 - this will still function the same way

Currently, when the ignition is initially turned on, the headlights come on immediately.
Triumph incorporated a 'cut while starting' feature however, so that the lights go off while the starter motor is engaged.

But here is a fairly simple modification that takes it a step further
- by adding in one more relay, the lights will remain off completely until after the starter is pressed and released.
(note that lights will not come on until the button is actually released, not when initially pressed)
Total cost will be less than $10
You need one 12V relay (20A minimum rating), a couple of diodes and some wire - that is it!

How it works:
When ignition is first turned on, the new relay will be 'off' inhibiting power to the OEM starter relay.
When the starter button is pressed, the new relay will energize along with the OEM starter relay, completing the circuit through both relays to the starter solenoid.
When the starter button is released, the 'new' relay will remain on however - it will self-latch because of the connection from its output (87) back to the input (86).
The diode in the starter line prevents the current from flowing back to the starter relay, otherwise it would keep the starter relay energized.
i.e. diode allows the starter signal to flow to the new relay, but not from the new relay to flow back to the starter signal.
And when the starter button is released, the OEM starter relay de-energizes and switches power from the now-latched new relay, to the headlights.
The new relay will remain latched on as long as ignition switch is on - will reset when ignition turned off.
The diode is added across the coil for turn-off spike suppression (good practice when adding relays for ANY purpose)

This will make for minimal drain from battery when you first turn on ignition. Also useful for those maintenance activities (like TuneECU for example) where you might want to have the ignition on, but not have lights on.

A couple of assembly tips:
you can actually pop the cover off the relay and solder the suppression diode and the 87 to 86 link directly inside and replace the cover. Then you just have wires/spades coming off the relay.
You can make up your relay assembly with its wire harness off pins 87, 86 & 85 - then when installing just remove the spade with the blue/yellow from the OEM relay & install on the new relay pin 30.
Then replace that terminal with the new wire from the new relay output (87) and finally splice the new relay coil wires to the starter signal (via diode) & ground
When installing diode in-line on the new starter signal wire, you can slip a piece of heatshrink tubing over the entire diode once soldered - add something like a piece of zip-tie inside the heatshrink just to add some rigidity to prevent the joint ever breaking from handling. (like a medical 'splint')
Diode secection requirement is fairly liberal electrically - will only be about 150mA of current through it - but a higher rated current diode is likely to have thicker leads, which is preferable from a purely mechanical perespective.



* Note that if bike fails to start initially, after the starter button is released, the lights will be on even if engine has not fired; however they will 'cut' again as soon as the button is pressed again, as per the 'normal' cut function.

Yeah man! My next project, thanks Ken.

Wow ! This stuff is cool , Ken . Thanks .

Hey Ken - If I do this mod, I think I will need to find an alternative relay activation power source for my voltmeter. At the moment it is powered by the blue/yellow wire in the headlight relay. Am I right in thinking that, if I do this 'headlight cut switch mod' this will mean my voltmeter won't be powered during the state: ignition on - not running?

I know I will still get power when the engine is running (headlight on) and my ignition bypass switch will feed the voltmeter power when the ignition is off.

Where do you suggest I should get the power for the relay activation for the state: ignition on - not running?

I guess that might sound a bit confusing. Maybe this will clarify. There are three states where the voltmeter can currently measure:

1. Ignition off - powered directly by the battery via my switch. This will still work.

2. Ignition on, engine running - powered directly by the battery via the relay which is activated by the headlight relay. This will still work also.

3. Ignition on - engine not running (headlight off). This is the issue.

Sorry to get long-winded.

Aha!

Maybe I see the solution (correct me if I'm wrong). Looking at your modified circuit - if I take my (ignition switched) power source from the input power source of the new added relay (the blue/white wire in your diagram) I should be sweet.

Thanks a bunch for this, Ken. I can see it ending up in the Tech Vault.

Maybe even easier Rich - does your model normally require the clutch to start (when in neutral)
- if so & you want to check the voltage under ignition, not running, just thumb the start button without pulling the clutch lever - that will set the first (new) relay but not the OEM start relay and put system in the condition that it is currently.
The first relay just needs the positive 'start signal' to energize since the other end of its coil is permanent ground.
And the (now) second relay will turn lights on immediately since it is normally closed (but needs the 'low' side enable from the ECM on the Yellow/Brown wire to actually energize, so will not operate the starter)

If your bike currently starts without pulling the clutch (when in neutral), then it would do the same thing but you would need to click into gear - and leave clutch lever open.

That would also be a means of turning lights on if you didn't want to start, even without your special voltmeter requirement.
Sorry - I'm not 100% sure of the logic on the clutch vs no clutch for starting on the different models - I know with the carbies that if neutral did not need clutch lever, but not sure if that carried over to the EFIs.
(you need clutch for all the Triples, regardless of in neutral or not)

Hi Ken, Thanks for that. Back to the post subject ....

Internal Relay Wiring Question for the Headlight Cut:
Is there any difference between wiring the new relay as your drawing or by connecting 86 & 87 (as per) BUT running the diode from 85 to 87?

I'm an electrical neophyte but that looks like the same connection result. The reason is that the relay I have is a slightly different layout to the one illustrated - same relay and connections but the connections are one to each of the four sides and my suggested wiring is a bit easier space-wise.

Are you talking about the suppression diode?
Since you have 86 & 87 connected, sure - will come to same thing.
(you might just want to mark that relay as 'special' so down the road a ways it doesn't get swapped into something else)

Great! Thanks Ken. Good suggestion about marking the relay - my memory isn't getting any better.

They say it's the second thing to go Richard!

I've forgotten what the first thing was ...

Just so everyone understands what you mean Rich, here is graphical view of it

And here's the modified relay. I didn't have to use any wiring internally - just bent the diode wire elegantly around the three connections and soldered it in place.




The diode is the little black cylinder with the grey stripe at one end.

Ah - pics are worth a million words as they say!
Excellent job Richard!

Woohoo! All installed and operating 100%.

No more headlight coming on before the engine fires up - then it comes on automatically after releasing the starter button.

I couldn't mount the new relay right beside the existing headlight relay - no room on my bike (an EFI model) but I believe there's a lot more room under the tank on the non-efi models.

So I mounted it about 8" further back (where the AI pump used to be) so an extension of the blue/yellow wire (and also the return from plug 87) was therefore required - but all went well. I also ended up moving the external diode so that it jumped across the connections in the old relay - jumping from position 1 to 3 - which is the same circuit but it eliminated a join in the wire coming from the starter button.

Thanks to D'Ecosse for the concept and circuit.

I had a slight hiccup trying to figure out which connection was which on the old relay - there was no identification on the plugs. Obviously the blue/yellow wire was easy to identify but it was not clear which red/white wire (there are two) comes form the starter button.

I did a little research on the Omron G8HN relay and finally found this schematic. I have added the correct wire colours. Note that this is viewed from the bottom.

Sorry about that Richard - I should have provided that for you.

Not to nit-pick, but the wires are actually White/Red, not Red/White (subtle difference, the dominant colour is always first) - and you might designate the one on pin 1 as from the Starter Switch.
Yes, it's important to get the correct White/Red, the one connected from the starter switch to the coil of the OEM Starter relay - the new relay has to make in order for the starter relay to have power at its input pole before it can supply to its output - if it was connected to the output white/red it would switch the starter relay before the power got to its input.

So - the big question: does it work 'as advertised'?

It works perfectly. Thanks mate.

I will fix the wording on my pic to 'starter switch' this avo - I gotta race out now.

Doooh - I completely missed the post before the one with your relay diagram!
From that post, great input on incorporating the starter diode internally across 1 & 3 - good spot on that one!

Here are your ideas pictured graphically - your pioneering should hopefully help others execute this quite easily.

Yes that's it - except the 5 plug oem relay on my bike is a sealed unit - so the diode is jumped EXTERNALLY across the plugs 1 & 3.

Still more efficient connection, Richard - excellent job.

Richard (and anyone else contemplating this mod)- please see revised schematic below



Functionally, the original is OK - however when start signal is present, the diode feeding start signal to the new latch relay, will also supply current directly to the input of the start relay - that means current to the start relay will actually be shared from the start control signal itself and the input power (Blue/Yellow)
More correctly, the latch feedback originally shown as a jumper should be a diode.
The downside to this is you cannot connect the start signal diode directly across the start relay (between pins 1 & 3) - although there is no real requirement to change the suppression diode location between 85 & 87 - the new additional diode between 87 & 86 will serve both as a froward diode for the latch and and also in reverse for the syuppression, where it will effectively be in series with the suppression diode connected as per original.

Edit capability times out too quick on this site!

My PB Bandwidth for month was exceeded so pics not showing (will be restored on 26th)

Here is above post again

I'm surprised more of you haven't jumped on this - it is quite a nice mod and probably easier to execute than maybe appears.

Here is step by step process on how to wire this up
All you need is a relay, socket (ideally) and three diodes.
I like to use the compact Panasonic relays - good for 20A and much smaller/neater form factor that Automotive style relays.
You can also use the Omron style relays used in the later FI bikes - also compact (and OEM has built in resistor so can skip D3)
But a Generic 4 terminal automotive relay may also be used. (or even 5 terminal - just ignore the 87a centre terminal which will not be used)
Just be sure to identify the terminals appropriately for whichever relay you end up using.
I would advise a 20A mimimum rated device - although you could probably use 10A and still be comfortable for a single headlamp application.

Step 1.

Prep first relay terminal by joining the three* diode cathodes (ends with the white stripe) together and crimping/soldering.
This terminal is for the 86 location in the relay socket

* Note that if your relay has built-in suppression diode or resistor, you may omit D3 and only require two diodes (see step 5)



Step 2.
Crimp/solder the Anode of ONE of the three Diodes and a 14 ga wire together to another Terminal.
This terminal is for the 87 location of the relay socket.
(This wire will be the Output wire ultimately connecting to the OEM start Relay input)



Step 3.
Connect the Anode of another of the three diodes to an 18 ga wire.
(This wire will ultimately connect to the White/Red starter signal wire)



Step 4.
Heatshrink over the diode and wire from step 3



Step 5.
Crimp/solder the Anode of the remaining Diode along with an 18 ga wire together to another Terminal.
This terminal will be for the 85 location of the Relay Socket
(This wire will be the Ground wire for the relay coil ultimately connecting to a common ground reference)

* If a relay utilizing built-in suppression is used, connect the ground wire directly to the termnal without the additional D3 diode



Step 6.
Install the three assembled terminals into the 87, 86 & 85 locations of the relay socket.
Of course plan ahead for whatever relay/socket you are using to ensure the correct locations are selcted.



Step 7.
It is critical that the two exposed Anodes do not touch!
These should be physically isolated from each other and coated with something like liquid tape or heatshrink over the idividual components.



Step 8.
Final step can be to tidy with heatshrink sleeve.



Installation:

1. Remove the Blue/Yellow wire/Terminal from the input to the OEM Starter Relay and insert this wire/terminal into the remaining open location (30) in the new relay socket
2. Attach a Terminal to the Blue Wire and insert this in the OEM Starter Relay socket location from which Blue/Yellow was removed in step 1
3. Attach the starter wire from the new relay to the white/red wire of the OEM Starter relay (if your relay has two white/red wires use the one on the input side i.e. from the start switch)
4. Connect the black wire to a ground circuit wire (any) or battery negative.

That should complete the process and ready for test!