someone will know

[spart666]

hi guys
last job left to sort out
need to have some indication of when im going to run out of fuel
using motogadget clocks
from what i can make out busa original clocks have a guage and an led warning light that comes on when you are running out
want to use the led warning light i can rig it up to the hazzard warning led on the motogadget clocks
the issue
looking at the wiring diagram i cant tell what color wires go to the fuel light busa k3/k4
need to know the positive and negative
any help would be a brill:smile:

[RevHead]

google busa with the year ,wiring diagram,

[oldskool]

"Some one will know"
Mr fuckin helpful, bet ya didn't think of that one Al.

[EXBEN]

Unfortunately the stock tank sensor doesn't just use a positve & negative to switch on a led, they use a fucked up load resistance type setup.I've made this type of setup with a relay & a 3.4w globe then wrap it in tape or heatshrink & stick it somewhere under the tank or seat.
http://img4.uploadhouse.com/fileuploads/9366/9366860e429f75f80c583cd94ce33eae35a3cce.jpg

[EXBEN]

Here's the relay wiring diagram,It isn't on much of the time so the globe lasts well, Ive done a few & they are all still working, although if it stops working you know you've blown the globe.
http://img8.uploadhouse.com/fileuploads/9367/9367163-holder-3b58fe5e0f0045594563eceb80bccd0c.jpg (http://www.uploadhouse.com/viewfile.php?id=9367163&showlnk=0)

[EXBEN]

Sorry I can't get the last image to embed properly, the layout is as follows, Red goes to switched power, black goes to the tank sensor wire which is Yellow/black at the dash on the Busa, yellow goes to the positive led lead then connect the negative led lead to ground.

[EXBEN]

The way the circut works is as follows, when the resistance in the tank sensor drops (empty) the globe turns on which switches the relay & allows the power to flow to the LED.
If any electronics experts know a better/easier way to do this I'd love to know because this is the best I can come up with without getting dedicated PCB's made up.

[spart666]

brilliant il have a go at that and let you know
got to order a relay
but what is a globe havent heard that term before?
thanks for the help

[Redmohawk]

Whats the resistance of the tank sensor at full and empty Exben ?

[EXBEN]

quote:spart666 Posted - 13 Apr 2011 : 00:35:34
--------------------------------------------------------------------------------
brilliant il have a go at that and let you know
got to order a relay
but what is a globe havent heard that term before?
thanks for the help
Just an ordinary 12v 3.4w light globe, light bulb whatever you want to call it. Like the one out of an interior light in a car, any 12v 3.4w globe will do though.

[EXBEN]

quote:Redmohawk Posted - 13 Apr 2011 : 06:01:34
--------------------------------------------------------------------------------
Whats the resistance of the tank sensor at full and empty Exben ?
I haven't got one handy, apparently they use a thermistor so it would need to be conected to a bike to test as it passes a current across the thermistor that changes the resistance of the thermistor as it heats up (when the sensor comes out of the fuel).This is how I understand it anyway.

[Gix11]

quote:Originally posted by spart666


but what is a globe havent heard that term before?


As Ben said mate, it's just an Australian term for light bulb.

[Redmohawk]

If you bump into those details and conferm its a thermistor I might be able to help you out with a solid state equivalent , but to be honast prob just as easy to use the setup you have. If you want to make it more robust (removing the light from the equasion) there are possablitys of a diode resistor arangement.

[ozzy1100]

fuck ben you still come out with some shit the surprises me mate top shelf

[el sammo]

quicker to just use a ciggie lighter to inspect the fuel level in the tank

[Dynomutt]

It's a festoon bulb here in the UK. The other option is to add a small resitor in place of the bulb, it will do the same job of increasing the load.

[EXBEN]

No it doesn't work with a resistor.

[Booster]

busa colors.... black with white stripe is gnd, there will be 2 , the light one is sender , heavier one is fuel pump , and powered side is black with green

[Redmohawk]

The reason it works with a globe and wont with a resistor is that the globe resistance and current draw changes with the bulb temp , a resistor doesnt change and so wont work. A special diode called a zener diode of the right voltage and current with a resistor will do basiclly the same thing. But I need to know resistances to work out current flow etc. A relay has a resisstance of around 600 ohms but i need to know full and empty resistance and or current of busa setup to work out right diode to use.