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Discussion Starter · #1 · (Edited)
HEADLIGHT CUT MOD

As mentioned earlier, DEcosse designed a headlight cut feature for the ST similar in function to those he has designed for other bikes.

Purpose: To incorporate a feature that powers the headlights after the start button has been enabled and released. This feature could be considered Headlight Cut Until Started.

Background: The ST does not have a separate light switch therefore the headlights are powered when the ignition key switch is enabled. The headlight circuit is powered off while the start button is enabled and the lights remain off during the starting process. That feature could be considered Headlight Cut While Starting.

Mod Function: When the Ignition is first turned on, the new Delay Relay will be "off" inhibiting Ignition Supply to the OEM Headlight Relay coil, so Lights remain 'Off'. When the start button is enabled, the new Delay Relay energizes along with the OEM Starter Relay: the new relay will then in turn will enable the OEM Headlight relay; simultaneously, however, the OEM Start relay will switch power to the starter solenoid., while decoupling power to the OEM Headlight Relay; therefor lights still remain 'OFF' at this stage during the actual engine start. When the start button is released, the new Delay Relay remains on, because it will self-latch due to the connection from its output (87) back to the input coil (86). The Delay Relay therefor remains latched from then, for as long as Ignition is 'on', but but resets (drops the latch) when the ignition is turned 'off'. Concurrently when the start button is released, the OEM Starter Relay de-energizes and switches power back through its 'Normally' Closed contact and directed on to the OEM Headlight Relay (which is already 'on' from the previous stage) and thus out to the headlights.
The diode in the starter signal line prevents current from flowing back to the Starter Relay, otherwise the latched Delay Relay would also keep the start relay energized. The diode across the coil of the new Delay Relay is standard turn-off spike suppression.

Mod Benefit: Minimal drain from the battery each time the ignition switch is turned on. Also useful for maintenance activities, such as TuneEcu operations for example, during which you might need the ignition on but want to avoid battery drain due to the headlights being on.

Headlight Operation, Post Mod: Switch on ignition and the lights remain off. Start the bike by actuating the clutch lever and enabling the start button. Release the start button and the headlights will power up. To power up the lights without starting the bike, enable the start button without actuating the clutch lever.

Note: There are published designs accomplishing this mod utilizing electronic components. This concept has the benefit of being easily understood and constructed by virtue of being a simple relay versus an electronic circuit.

Parts:
New headlight delay relay. It can be, but does not need to be, automotive since only switching <200mA.
2 each, 1N5399 diodes (Radio Shack # 276-1114.
Radio Shack reed relay 275-0233 is an alternative which can be assembled along with the diodes on a circuit board. Block diagram attached.
Hookup wire.
Misc. TyWraps.

Assembly Tips:
If using an automotive type relay, the top/cover can be removed by prying the cover latches on the bottom. Once the cover is removed, the suppression diode and the 87 to 86 link can be soldered in place and the cover snapped back in place making for a neater installation.

Mod Construction Schematic: Attached.

Bonus: An 06ST schematic in which DEcosse has replaced the individual component find numbers with component nomenclature, including ECU pin outs. Not needing to reference the component find listing is very convenient. This schematic also includes some of the electrical mods on my bike.



View attachment Full page fax print.pdf

Text Line Diagram Font Auto part

View attachment Sprint_Modded.pdf
 

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Thanks OldnDumb & D'Ecosse. I can thoroughly recommend this excellent mod having just implemented it on my '06 Speed III. Easy and cheap to build and install, it works like magic!!
 

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Discussion Starter · #3 ·
This upgrade is one of those that will not initially garner much interest, but will be recommended by anyone that actually installs it.

Operationally it is deceptively intuitive and will make the stock lighting control system seem inefficient. If you have more than one bike and do it on one, you will want it on all of them.

On a side note, the bonus attachment in this thread's original post is a very valuable resource for those working on their own bike, and others who only care to have an understanding of their bike and how the electrical components interface. It could even prepare one to understand what their service department is talking about, or to correct them. :D
 

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OnD the attached "full page fax print.pdf" in post #1 appears to be damaged.
Neither Acobat 5.0 nor Adobe Reader 9 will open it
 

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Different numbers terminals on relay??

Well I finally got all my stuff, including a nice compact little relay with built-in suppression.
It's terminals are numbered 1,2,3 & 5. How do these relate to the 30, 85, 86 & 87 numbered terminals on the conventional relays?

Whoops, Dave HELP!!
Wrong thread. Could you shift this to:
http://www.triumphrat.net/sprint-forum/179467-headlight-cut-mod.html
 

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Discussion Starter · #13 ·
1 = 85
2 = 86
3 = 30
4 = 87

This is an assumption, not actually knowing the internal diode orientation. Otherwise, reverse 1 and 2.
 

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Will a 1N4001 (1A load) diode work in place of a 1N5399 (1.5A) as shown? I've had a look at the data sheets for both & I think it'll be OK.

Actually, on closer inspection the Peak Repetitive Reverse Voltage for the 4001 is 50V and the 5399 is 1000V. Hmmm. Getting out of my depth here.

I've got a bunch of the 4001s.
 

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Another question (I've PM'd DEcosse too):

The thumbnail picture of the relay shows one diode connected between 85 & 87 of the new relay, but the description @ item 4 says to connect between 85 & 86. Is there an error here, or am I misreading it?

Cheers
 

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i did this mod a couple of days ago it all went perfect and now there is no double strike on my HIDs,, a big thankyou to all the clever clogs that thought this mod up :):D:):D
 

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Just did this mod today, after buying the relay and diodes last summer. Probably should have been the first mod I did on the bike when I got it 3 years ago.

I did run into couple of issues with the instructions. No fault of OnD or D'Ecosse, I'm sure.

First issue: The instructions in OnD's post #1 are slightly different than the repost of the document in post #7. In the last step (6) of the instructions on the document, you are instructed to connect to a white/red wire in the #1 version, and a black wire in the #7 version. I tested both ways, and both work. Not sure which would be better, so I went with the #1 version, as it seems to be a newer document (includes a pic of a modified relay)

Second issue: Step 1 of the instructions says to "Remove Red/Blue wire from OEM Relay...". So I did. And the mod refused to work. The new relay would activate when the ignition was turned on, which is the opposite of what the mod is supposed to do. After about 5 hours of frustration (including buying some new diodes as I figured I might have blown one up :), and rechecking my work about 15 times, it suddenly became clear. The circuit diagram clearly shows that the Red/Blue wire mentioned is on the 86 terminal of the OEM relay. On my bike, the Red/Blue wire is on the 30 terminal of the relay. MY 86 terminal has two green wires. D'oh!!!! About 30 seconds of work to swap the requisite wires, and the thing works like a charm.

So, anyone considering this - look for the 86 terminal, ignore the wire color :)

Which brings up a question - I wonder how many variants of wiring exist? If not in circuitry, then in wire colors...
 

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Well done Iggy.

I hope you upgraded the wiring guage for the headlights (both active and earth) while you were at it. Gives alot more luminance.
 
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