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+--- Thread: Where to tap speed sensor signal? (/showthread.php?tid=8683)
Where to tap speed sensor signal? - egleaves_imp - 07-04-2018
I recently purchased a [url=https://www.revzilla.com/motorcycle/signal-dynamics-brake-hold-module]Back Off module by Signal Dynamics that also includes their Brake Hold feature. Brake Hold will Keep the brake light lit the until it receives a signal from the speed sensor indicating positive acceleration.
Has anyone ever tapped the speed sensor wire for something like this? Where is the best place to tap it? I'm thinking I'll need to get into the instrument cluster to tap it near the tach. I don't want to cut into any factory harnesses.
RE: Where to tap speed sensor signal? - SportsterDoc - 07-04-2018
For a 2014 standard, which does not have an ABS modulator, the post model year 13 schematics show a pink/green wire to position 1 in the instruments. However, tracing that wire on the schematic shows it going nowhere, whereas on the ABS models it goes to the ABS modulator with inputs from both front and rear speed sensors.
Is this your module? http://www.signaldynamics.com/brakehold
The referenced schematics are pages 20-4 and 20-5 of the FSM. I have only a merged scan of those two pages and there may be something missing.
Until you have better info, I would probe the pink/green (position 1 of 10 pin connector) for a 0-5 vdc signal with the bike on the center stand, motor running and in gear. Expect the signal to vary as the speed changes.
RE: Where to tap speed sensor signal? - max - 07-04-2018
Assuming yours has no abs, there is a 10 pole connector inside the headlight which has a pink/green wire.
this carries the ( i think ) low level signal from the rear wheel speed sensor, i would test the voltages with a multi meter ( or ideally an oscilloscope or similar ) to prevent damage to the instrument cluster ( these wires usually connect to a microprocessor input which handles a lot of different functions ) and if the voltage is compatible try to connect to the speedo wire with a suitable resistor in series.
you may need to call in a favour of someone with good electronic knowledge.
( sportsterdoc beat me to it but similar results )
RE: Where to tap speed sensor signal? - peterbaron - 07-04-2018
I like this fair competition
to both of youI looks to me like you both not riding enough...lol..lol
RE: Where to tap speed sensor signal? - max - 07-04-2018
That's right, its 12 degrees here and no sun today so i'm hybernating.
Saw egleaves' question and when i was finished looking for the answers i noticed sd's reply, good to see we've come to the same conclusion, which is the reason i did not delete mine, well said Peter!
RE: Where to tap speed sensor signal? - peterbaron - 07-04-2018
RE: Where to tap speed sensor signal? - egleaves_imp - 07-04-2018
Good info, I'll probe the suggested wires. Seems like my suspicion is confirmed, that I'll need to open the instrument cluster...or maybe the headlight bucket. Didn't think it would lead there, but sounds convenient.
SportsterDoc, that's the one.
A little competition keeps us all on our toes. Thanks guys!
RE: Where to tap speed sensor signal? - SportsterDoc - 07-04-2018
(07-04-2018, 11:13 AM)peterbaron_imp Wrote: I like this fair competition
I looks to me like you both not riding enough...lol..lol
Max may be hibernating, but I am not.
Although probably only a little over 100 miles, tomorrow.
Not at all competition, just team work!
And thank Max and Popgun for my access to a schematic!!
Max, what is your thinking about a resistor, as the Signal Dynamics page makes no reference thereto?
RE: Where to tap speed sensor signal? - max - 07-04-2018
Sorry SD, late response;
warning; tech babble ahead.
Was thinking the input to the sig-dyn unit was hopefully high impedance to not load the ecm output and a 10k 0r 47k resistor would separate the unit in case of a failure, somewhat like a fuse.
it would protect the ecm in case 12 volts were to become present on the white wire and limit the fault current to 1mA or less since i have no idea what the safe input level was to the ecm/instrument cluster and it is possible that the speed sensor has only 100 milivolts output if it is a reluctance sensor ( a small coil that picks up pulses from the abs tone wheel ).
On one diagram it calls the pulse input + and - on the abs unit, not sure what that means, hence the suggestion of an oscilloscope which displays the waveform and value of it rather than an average value on a multimeter, just to be on the safe side and not knowing enough about either unit.
RE: Where to tap speed sensor signal? - peterbaron - 07-04-2018
All I know is a friendly team/work competition = well done