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Does anyone know about the speed signal that feeds the ECU from the dashboard?
To explain, I'm building a Marlin Sportster and trying to find out what type of signal is generated by the original dashboard (Black/White wire. If you know BMW electrics).
There is a reed switch feeding the dash (giving it a 12v square wave) which then comes out to feed the ECU, A/C, Cruise Control, Wipers, Etc.
Because I'm using different dials, and the fact that I've thrown the old dashboard, I've no way of discovering the signal.
Unless someone has an old dashboard going spare that I can rig up.
I'm not sure the dash does anything with it... And I don't recall feeding anything too my ECU relating to speed, as I hadn't hooked the sensor up at that point, and it seems to run just fine.
Could be wrong though, as she hasn't turned a wheel yet!
I can't remeber which engine you're using though... Is it an M20 out an E30?
What I'm trying to find out is the signal from the dash.
I've used the BMW wiper motor and module which needs this signal.
The module needs to know if the car is moving so that the slow speed wipe goes to intermittent when stopped.
At the moment the module thinks that the car is stationary so I've got no slow speed wipe.
This signal also goes to the ECU.
Why?
Haven't a clue.
BMW must have their reasons I suppose.
Maybe the onboard computer??
Perhaps it just a signal that indicates when you are moving or not? In that case just pulling it high or low (use a highish value resistor first) might do the trick. Have you looked inside the BMW ww control module to see what's in it? I guess it can't be too complex as the E36, while newer than the E30, is still quite old.
