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Discussion Starter · #1 ·
This is for bikes without a headlight control switch - this fairly simple mod will keep the lights off completely until after it is started.*

* 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 that is the current scheme.

If you want to skip the circuit and theory operation, skip on down to post 16 for a step-by-step process

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), Three* diodes and some wire - that is it!
* If you use a relay that already utilizes suppression resistor or diode, you will only need two diodes
Common or garden automotive style 4-terminal relay without on-board suppression is shown

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) through the diode (D2) back to the input (86).
The diode (D1) in the starter line prevents the current from flowing back to the starter relay, otherwise it would keep the starter relay energized.
i.e. this 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 (D3)* is added across the coil for turn-off spike suppression (good practice when adding relays for ANY purpose)
*D3 not required if using a relay with internal suppression (diode or resistor) already

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.

Edit: Slight modification to initial schematic

The following is actually preferable way to do it

After the initial post, I noted a (fairly minor) 'issue'; Initial circuit had a direct link instead of D2.
With that design,when the start button is pressed, current would conduct through the diode directly to pin 87 of the additional relay, thus 'sharing' the current to the starter relay.
To avoid this condition, you may add another diode in place of the direct jumper link as per below:



Note that you can omit the Suppression Diode (D3) between 85 & 86 completely if you use a relay that has a diode (or resistor) already installed.
The suppression diode is not integral to the actual circuit mod, but good practice when installing any relay in any application (often omitted!)



D3 could probably be connected between 85 & 87 as D2 would complete a series circuit for the reverse suppression condition - may be easier to solder
As drawn is more correct.

This shows the relay integrated into the Carb Bonneville schematic - other carb Twins are similar and the EFI is also very similar
(shown in the block diagram above)

 

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I've just though of another good thing about Ken's mod. It saves the ignition switch contacts suffering from the headlamp current and its initial high surge amps. Incandescent bulbs have a very low resistance when filament is cold and draw a huge current for a millisecond or two.

The ignition switch on Triumphs can do with all the help we can give it, not the greatest component in the world, as shown by many burned-contact examples.
 

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I have just finished installing Ken's mod. Easy to do and it works great.

Here's a pic of the oem relay (Omron G8HN) on the EFI America showing which wires are which (there are 2 RED/WHITE wires and this shows you which one comes FROM THE STARTER BUTTON.

 

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I ordered two suppressor diodes from maplins that came today.
The ones I have been sent dont have the identification band on. It is written P6KE100CA / A46.
It's possible I have ordered the wrong ones or I have been sent the wrong ones as the picture on Maplins is different to the ones I have been sent
http://www.maplin.co.uk/600w-bidirectional-transient-voltage-suppressor-diodes-46421

Can anybody help me with this.....thanks
 

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Discussion Starter · #10 ·
That is bi-directional suppression diode (like two zeners back-back) and can be connected either way for the suppression device
However that will NOT work for the one in the start signal, which needs to be a regular diode. http://www.maplin.co.uk/3a-silicon-rectifiers-46405

Please also note edit in original post for revised alternative that is more properly correct.
 

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That is bi-directional suppression diode (like two zeners back-back) and can be connected either way for the suppression device
However that will NOT work for the one in the start signal, which needs to be a regular diode. http://www.maplin.co.uk/3a-silicon-rectifiers-46405
My local Maplins have those in and only close in 1 hour so on my way to collect now, should have known something was wrong when the first ones I ordered they didn't have in stock :huh:huh:

Thanks Decosse
 

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Ken, this is an excellent mod for our bikes and I will be carrying out sometime over the next few weeks, thank you.

It will be even more valuable to EFI twin owners with the under capacity slim battery that gives some trouble.
 

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Discussion Starter · #13 ·
Appreciated Mike - pretty simple & inexpensive to execute but makes for really nice functional improvement.
And if need to turn lights on without starting, the start button becomes the 'on' switch regardless - just press the button without the clutch lever
(although that is only for EFI's - with carbies if in Neutral it will start, but that can be overcome by having in gear and again no clutch lever action)
 

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Discussion Starter · #16 ·
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 than std. 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.

For diodes (for example)
In US - from Radio Shack Model: 1N5399-S RS Part #: 276-1114 - http://www.radioshack.com/product/index.jsp?productId=2062575 ($2.19 for pack of 3)
In UK - from Maplins - 1N5404 - Part # QL84F (£0.29 ea) or 1N4007 Part # QL79L (£0.24 ea) http://www.maplin.co.uk/rectifier-diode-19079

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

 

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Discussion Starter · #17 ·
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!
 

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The third diode, will that stop my HID light firing on and then off just for a split second as I press the start button ?
 

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Discussion Starter · #20 ·
The third diode, will that stop my HID light firing on and then off just for a split second as I press the start button ?
Possibly - the 'short' instead of the diode means that the start signal is immediately coupled to the input pole of the starter relay, which is seemingly coupled through the N/C pole briefly before the OEM relay has a chance to switch states.
So by employing the diode the new relay will also have to complete its switching action before it applies power to the starter relay pole. This should add a finite time - just as the OEM relay takes time to switch off the headlight pole, the new relay will also have a similar time to switch power through its contacts.
But might still be close

If that doesn't do it, you can go this way
- you can switch the relays around so that the cut relay is after the starter relay instead of before - and you would then run the cut relay coil input off the starter relay switched output, rather than the control signal. This would ensure that the starter relay has already changed states before the cut relay gets its 'on' signal (and then it will also have some propogation time after that)

This is probably the best way to deal with it
- this method should only be required for HIDs.



This one will still also work for non-HID application - the added complexity - albeit just adding one more component- is not necessary - but use it if you wish
The only other 'downside' to this one vs the original is that you can't turn the headlights on with just the start button (needs 'regular' start)


Now the cut relay is after the start relay and it won't receive its 'on' signal until after the start relay switches states;
so there will be no power to the 30 terminal at that point either
But when starter button is released, in order for the relay to latch, the new relay has to delay turning off for long enough so that it can latch off the 87 output once the power is restored to the pin 30 input as the OEM relay turns off also.
So the capacitor across the relay coil will keep it on long enough to achieve that (about 0.25secs but that is enough)
A 470uF capacitor will do it (have tested this) - Maplins part # AT15R
Note that the negative end is indicated - it is polarity sensitive!

As mentioned in the brief note below the diagram, the other difference is that this one requires full 'start' condition in order to turn on the lights
With the original circuit, if you just turn on ignition, then press start button (no clutch) lights will come on without operating the full starter (at least for EFI - carb a little different)
With this revision, it needs the starter relay to actually operate, so needs the ECM interlock satsified (clutch, neutral, sidestand etc) and the starter will actually run before lights can be enabled.
 
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