1jz jza70 RPM pinout/TACH output

[forey]

firstly i have searched and couldnt find anything

autometer 3 3/4" tacho/VDO 4" Tach in z20 soarer

have looked at the ecu pinouts, tried both rpm outputs - nothing
tried the RPM wire on my greddy emanage - nothing
and also tried the wire on the first coil?? - nothing

cant get any readings, whats my problem?

thanks

[Mos]

Firstly, the tacho output is off the ignitor.
Secondly, are you sure the tacho works? Does it have different settings or inputs for positive or negative pulse, high or low voltage signal, etc?

[CrUZida]

I'm curious as the what these 'RPM' outputs on the ecu are?
Which pins were they?

But anyway, as Mos said, the tacho is driven directly off the ignitor.
Temporarily run a wire from the IG- pin in the diagnostics box to the tacho, see if that works.

[forey]

I'm curious as the what these 'RPM' outputs on the ecu are?
Which pins were they?

But anyway, as Mos said, the tacho is driven directly off the ignitor.
Temporarily run a wire from the IG- pin in the diagnostics box to the tacho, see if that works.

as per http://i2.photobucket.com/albums/y5/...cu_diagram.jpg
i tried both 17 and 23.

which wire on the ignitor do you wire to?

thanks

[CrUZida]

IGF and IFT are not tacho outputs, they are signals between the ECU and Ignitor.
While they may be the same frequency to the tacho signal, they are not the correct signal.

The ignitor tacho wire is the same wire as the IG- pin in the diagnostics box.
It will also come through the firewall with the rest of the wires.
One of maybe 2 black wires.

[forey]

found the diag box, its in a prick of a spot because the lead is really short and with my custom plenum it cant be pulled through the ports.
it seems the IG pin has a spade like connection, any inparticular?

is the wire visable/easier accessed in the engine bay?

[CrUZida]

That wire will go to the ignitor, as well as through the firewall. It may be easiest to get to it from behind the glovebox.

[forey]

thanks a heap +rep

got it working!