VDO Speedometer Signal

[cammmy]

Hi All

Hopefully an easy one. I'm using a v3.0 MS3/X. The factory VDO speedometer in my car is controlled by the ECU. Pulse per mile is completely programmable in the unit, which makes things easy; what I'm not sure about is the signal voltage.

The unit can accept a number of different signals, the one that applies to me is as below:

"4c. If you are using an electronic transmission, connect its
speed signal wire to pin #8."

http://www.nsifleet.com/pdf/ProgrammableSpeedometer.pdf

I can't find any info on the signal voltage it's expecting. I was looking to use Nitrous 1 to drive the unit; this would create a 12v square wave? Would this be okay?

I've found the below which references sending 12v to a VDO speedometer:

"Right, Ive got speed sensing sorted. I've got a TP500 module doing the conversion from the sinusoidal VSSensor output to 12V square wave which is then fed to GPIO as well as the VDO speedo gauge:"

http://www.msextra.com/forums/viewtopic ... do#p447803

Would this be okay?

Ta
Cam

[cammmy]

Hi All.

Managed to contact VDO. They said a 12v square wave is fine.

Last question, I believe Nitrous1 is a suitable output but would like someone to confirm before I start cutting/soldering. Is anyone able to advise?

Thanks
Cam

[dontz125]

Nitrous1 will work fine; you may need to add a 1k pull-up to 12v, if the tach doesn't have one internally.

[cammmy]

Brilliant, thanks Don

[cammmy]

Just for future reference if anyone else is looking for this info. VDO confirmed that no resister is required.

Their support is really good. Quick responses.

Ta