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Tacho output
Posted:
Tue Oct 21, 2008 6:03 pmby Wolf_Tm250
Hello.
In order to make the tacho output work for my Toyota original tachometer ( 20 volts ), I need to know how much is the voltage Aux4 output in an M400: 5v or 12v?
Thanks.
Re: Tacho output
Posted:
Wed Oct 22, 2008 6:38 amby Martin
Wire Aux4 to your Tacho and add a 4.7Kohm, 1/4 watt resistor between 12v and the tacho signal.
Re: Tacho output
Posted:
Wed Oct 22, 2008 6:00 pmby Wolf_Tm250
Martin wrote:Wire Aux4 to your Tacho and add a 4.7Kohm, 1/4 watt resistor between 12v and the tacho signal.
You mean to add that resistor between my tacho output AND a 12v wire of the car ?
There is another thing I can't understand on the M400 manual:
on the Aux Output page, there is no High Side driver for the Aux4 ?
Thanks again Martin !
Re: Tacho output
Posted:
Thu Oct 23, 2008 3:17 amby Martin
Yes.
You wire the resistor between 12v and the tacho signal.
the Mx00 ECU`s only do highside on the following outputs:
Aux1
Aux2
Aux5
Aux6
Aux7
Aux8
Regards
Martin
page 81, m400 m600 m800 manual
Re: Tacho output
Posted:
Thu Oct 23, 2008 5:39 amby Wolf_Tm250
Martin wrote:Yes.
You wire the resistor between 12v and the tacho signal.
the Mx00 ECU`s only do highside on the following outputs:
Aux1
Aux2
Aux5
Aux6
Aux7
Aux8
Regards
Martin
page 81, m400 m600 m800 manual
Ok...
Sorry but probably I haven't understand what high side and low side stand for:
doesn't "low side" stand for "grounded" output ?
In this case I can't use Aux4 as a Positive Tacho output...
Thank you.
Re: Tacho output
Posted:
Thu Oct 23, 2008 8:52 amby RossB
Yes "Low Side Drive" means that the output will switch to ground. You do not use High Side Drive for your tacho output though so you can use AUX4 if you want to.
Re: Tacho output
Posted:
Thu Oct 23, 2008 10:15 amby Wolf_Tm250
Thanks for the reply, RossB...
but i'm still thinking i'm missing something.
As far as i know, my original tacho output from the stock igniter is 20v:
how could i drive it with a low side signal, if it needs positive 20v?
Please help me understand what i'm missing, thank you.
Re: Tacho output
Posted:
Thu Oct 23, 2008 3:19 pmby Martin
Ive worked with a couple of toyota revcounters. Connect it as discribed and it should work. You will also see that if you select tacho signal on an output it will not allow you to do highside. Lowside works just fine.
Cheers
Martin
Re: Tacho output
Posted:
Sat Oct 25, 2008 12:14 pmby M800
In the interest of keeping Tacho related questions in one area, I have an additional question.
Can a tacho output come from a spare IGN?
I realise that Aux 5,6,7,8 have the 200Hz limitation, do the ign outputs?
Continue
Re: Tacho output
Posted:
Sat Oct 25, 2008 11:15 pmby PQatPIT
200 Hz is two hundred signals a second, it is twelve hundred signals a minute and that means 12 000 rpm. Usually it is enough but not always, and it depends on your tacho what kind of signal it wants to see. How high this engine revs and what is the tachometer?
PQ