Tacho output

[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.

[Martin]

Wire Aux4 to your Tacho and add a 4.7Kohm, 1/4 watt resistor between 12v and the tacho signal.

[Wolf_Tm250]

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 !

[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

[Wolf_Tm250]

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.

[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.

[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.

[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

[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

[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