Speedo Input for a race technology DASH2

[Black_Potato]

Hi,

Does anybody have any experience in how best to get a speedo signal into a Race Tech Dash 2 ?

I have most of the other inputs working but I was hoping to tap into the Brown/red wire in the loom behind the dash but I dont seem to be getting a reading.

Any tips or Gotcha's appreciated.

Cheers

Richard

[Black_Potato]

Hmm..

I'm guessing I may need one of these

http://www.race-technology.com/wheel_speed_2_61.html

[gromgsxr]

What type of signal do you need to feed in to the dash, I used the vss signal that fed the motronic ecu in to my megasquirt quite happily that's a 5v square wave signal. This may help also http://www.e30zone.net/modules.php?name ... a&start=25

[Brianmoooore]

Road speed sensor on an E30 is just a switch that opens and closes a few times per turn of a road wheel. To get a 'signal' from it you need to connect the brown/red to a power source through a resistor. You'll then get a square wave with a voltage range of 0 to the voltage of your power source, assuming the input impedance of your dash is high.

[Black_Potato]

I found this....
For the speed sensor, the BMW diff sensor is basically a switch that closes 9 times per revolution. Think of the dash speed input as a volt meter. It just measures a voltage. So ground one end of the diff sensor and put the other side to the speed input of the dash. Then from that input run a 1K resistor to battery power. You now have a nice 0-12V square wave to measure. You don't need to use Vref for this. Save it for active sensors.

0V -----/diff/----/dash/----/1k/---- 12V

Assuming your tires are about 2m in circumference, you need to program the dash in the menu for 7226 pulses per mile.

which seems to explain a bit further what Brian was saying. , however my electronics understanding is limited so does this drawing make sense ? if not can you help me correct it ?



Thanks.

[Black_Potato]

maybe this is closer ?

[Brianmoooore]

Definitely the second diagram!
You should take the power from an ignition switched source (green/x or purple/x) and the fuse isn't required.

[Black_Potato]

Thanks Brian....

Option 2 worked