Wheel speed/oil pressure sensor question..

[SantaClaw]

I've got a Dash2, and an AX22 connected together.

Question 1.

I'd like to use a Bosh crank sensor as a wheel speed sensor..

The Bosh sensor, looks identical to the one that Race-Technology sells, at least visually..

3 leads, Two brown and one blue...


According to the car's wiring diagram, the blue one is am RF shield for the two other wires, its connected to something called: GRRT/GRSW..

Whilst the two others go through the sensor..


So just connect the two brown ones to "Wheel speed input 5-12v Brown " and "5v Reference Output 50mA max Grey" on the dash 2 with a 1k ohm resistor between the wires ??



Question 2.

I've got a VDO dual oil pressure sender, it's rated 0-10 bar 0-160 ohm.

Can I use this sensor with the Dash 2 ?

[SantaClaw]

I've fitted the wheel speed(crank) sensor... I have connected an ohm meter to the leads from the sensor.. It reads 552 ohms.

When I spin the wheel, by hand, it drops to about 496 ohms when it passes the bolt I've placed on the brake disk. I don't have that 1k resistance in place, but should it work once I do ??

I've calculated that there would be 884 pulses per mile..

As the diameter of the tire is 1.82 meters, and there's 1609 meters per mile, sound correct ?

[osborni]

I think you may have better luck getting some purpose made speed sensors with a VDC output. Cherry has decent ones from Digikey for about ~$25 IIRC.

The knowledge base has decent instructions on how to convert a resistance based sensor to a voltage.

[Support]

here is the page in the Knowledge Base that refers to how different types of sensors are wired, that might be of help: http://www.race-technology.com/wiki/ind ... WireSensor

With regards to the VDO oil pressure sender, this can be used with the DASH2 as long as you have the correct calibration to configure the DASH2.

[SantaClaw]

Thanx, I've been looking for that page

[GMS Racing]

This is from an old post of mine, but the data is still valid. This is the bar versus resistance data you need for the VDO 10 bar sensor. you will need to convert it to voltage by adding a pull-up resistor to +12v to create a voltage divider.

Bar Resistance
0 = 7.2
0.5 = 18.2
1 = 28.2
1.5 = 39.2
2 = 49.2
3 = 68.2
4 = 87.2
5 = 104.2
6 = 121.2
7 = 137.2
8 = 153.2
8.5 = 160.2
9 = 167.2
10 = 181.2

If you need info on how to calculate the voltage divider then have a look here:

http://www.race-technology.com/forum/vi ... light=audi

[SantaClaw]

This is from an old post of mine, but the data is still valid. This is the bar versus resistance data you need for the VDO 10 bar sensor. you will need to convert it to voltage by adding a pull-up resistor to +12v to create a voltage divider.

Bar Resistance
0 = 7.2
0.5 = 18.2
1 = 28.2
1.5 = 39.2
2 = 49.2
3 = 68.2
4 = 87.2
5 = 104.2
6 = 121.2
7 = 137.2
8 = 153.2
8.5 = 160.2
9 = 167.2
10 = 181.2

If you need info on how to calculate the voltage divider then have a look here:

http://www.race-technology.com/forum/vi ... light=audi

So in other words I need a resistor that's approx 180 ohms. ?

[GMS Racing]

I used a 15 Ohm resistor as it gives a wider voltage spread.



Note that I measured 4.98V on the +5V reference out from the DL1. You just input the voltage against the corresponding pressure value into the table provided to get your quadratic equation.

My equation is shown at the bottom of the pic (with grey background).

The calculation for Vout is:

Vout = Vin*((R2)/(R1+R2))

[SantaClaw]

I used a 15 Ohm resistor as it gives a wider voltage spread.



Note that I measured 4.98V on the +5V reference out from the DL1. You just input the voltage against the corresponding pressure value into the table provided to get your quadratic equation.

My equation is shown at the bottom of the pic (with grey background).

The calculation for Vout is:

Vout = Vin*((R2)/(R1+R2))

I've measured my refferance to 4,88v

I see what you mean..

But then I know what I need. I already did that calculation using 4,88v and a 180 ohm, resistance, that would mean 0.45 v @ 0 bar..

[pault]

Just a reminder, using 15 ohms at 1 BAR you have a current draw of 116mA. According to the technical specs for the DL-1 the 5V output is only good for 100mA.

http://www.race-technology.com/wiki/ind ... cification

Paul

[GMS Racing]

Good point, I never considered the current drawer. It's been working like that since 2006, so I will leave well alone.

[osborni]

It's pretty simple to make a separate power supply out of a linear voltage regulator. $5-10 or so.