Ishrub

Retired and loving it!
Joined
Feb 18, 2016
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8,317
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Duffy, Canberra, ACT, AUSTRALIA
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R3 Roadster,Sprint ST 1050 ABS, BMW R100RS sidecar
I have just had another look and the signal wire from the ECU is a resistance of 5.5K Ohms - not sure if that changes with the fuel level because the tank is raised so the sender will be in a strange position. The Koso setup options for resistance are 100, 250, 500, 1200 and a custom setting of up 1999 Ohms - none of which are a close match in any way. The confusion continues :unsure: :oops:
I am not sure of your wiring diagram source. Have you read @barbagris and @DEcosse posts in various threads on Koso and Dakota instruments? Don't forget @idk has the manual and wiring diagram links for the pre ABS Rocket IIIs in his signature block too.
 

RazMan

.040 Over
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Mar 31, 2022
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64
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Rocket 3 Classic, Trophy 1200 Bobber
I am not sure of your wiring diagram source. Have you read @barbagris and @DEcosse posts in various threads on Koso and Dakota instruments? Don't forget @idk has the manual and wiring diagram links for the pre ABS Rocket IIIs in his signature block too.
Yep, I spent a lot of time scouring the threads by these guys - very useful info which gave me the confidence to change the clocks in the first place :thumbsup: . Lots of info about the speedo functions but the fuel gauge wasn't really discussed as far as I can see,
I have come to the conclusion that the old signal wire to the std clocks will now have an independent LED, separate from the Koso - so that leaves the original gauge wiring to play with.
 

Frans

Supercharged
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Mar 5, 2021
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220
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2015 Rocket roadster
I guess my thinking is a little off happens sometimes.
The ecu (i think) is sending 5 volts to the tank sensor cant spell it
Then back to ecu reading the lower voltage depending on float level.
Then the ecu will send the signal out of A08 to the gas gauge
I do not know what that signal is ?
Not knowing anything but would the floater in the tank not provide a reverse resistance value? (full = low ohm, empty is high ohm) And the ecu uses some sampling/smoothing to make sure the resistor value to gauge translation is not showing/going up and down erratically and also use it to calculate remaining trip distance? Then the ecu is sending some msg to the gauge which could have nothing to do with the original resistance. If my assumption is correct then imho it would be possible to connect\split the wire from the floater directly to the koso ?
 

TURBO200R4

stand up straight and grab the world by the a$$
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Jan 24, 2013
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7,708
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TUCSON AZ
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07 rocket III classic
Yep, saw that one too - no connection details though - just that 'it works fine'
he says " i connected the wires directly to the accessory plug "
post #3
of coarse u have to question every thing till it works.
 

RazMan

.040 Over
Joined
Mar 31, 2022
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64
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Rocket 3 Classic, Trophy 1200 Bobber
Which takes us back to my first post :roll: asking which wire do I connect to the Koso?
I have tried all three without success
 
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