wiring microtech to tacho 1jz

[chris davey]

I have jzx90 chaser dash in my car and my tacho hasn't worked for ages.

I have the tacho output wire from microtech. It reads 12v at idle and drops to 10 or so when I rev it.

I am not sure which is the tacho input wire on the dash. There are 4 plugs each with 10 to 12 pins on them.

I have done this before (when I had the wolf) so I have it plugged it into the one that I used last time. It doesn't seem to do much?

I have checked the voltage at the input when nothing was connected and it was doing all sorts of weird shiznit. The tacho is still not moving at all. How can I get this POS to work?

Thanks

Chris

[Maverick]

Hey champ ,I wired in a jzx90 tacho into my mx83 instrument cluster, as the cressida one was 12V input and the 1jz ecu was 100V (or vice versa, I can`t remember)

on the back of the jzx90 cluster, the tacho circuitry has something like (+ve),( -ve) and (signal) labelled on the circuit board.(you have to pull the cluster apart for this, but its not hard) Make sure the tacho is getting power, i.e. theres 12v going to the +ve and the -ve is grounded. then solder a wire to the signal and this should go to the signal wire of the microtech. i`m pretty sure the signal from the microtech is not the same voltage as the jzx90 tacho, but go down to jaycar and get a signal convertor and from 12V to 100V, solder it into the signal wire and if the tacho is not faulty it will work

[wilbo666]

Chris,

I was under the impression that JZ powered cars took a 12V square wave input to the tacho on the dash, as that is what the tacho signal from the Igniter is.

This is different to older cars which work on the back emf of the coil to drive the tacho, there is a simple circuit involving a relay to converter 12V -> coil type around, but you shouldn't need it! (in short Maverick's advice shouldn't apply to you as the dash should be taking a 12V square wave signal already!)

I'd suggest removing the dash and tracing / finding the correct wire with a multimeter!

Also I'm not sure if the Microtech and Wolf tacho output is the same, perhaps find out if it is?

Cheers
Wilbo

[sideshow]

i make tacho boosters that work on most microtechs

ill be in brissy from june 30th to july 8th
i can bring one up for you if u want to pick it up

there 40 bucks

i have yet to see a microtech or wolf have enough power to work a tacho without needing a booster

[chris davey]

Thanks guys.

Well when I had the wolf the signal that I was sending to the tacho was from the stock igniter as per factory. This didn't work though.

I know that the microtech output is 12v at idle and then drops when you rev it a bit.

Actually the tacho booster may be correct as when I had it connected to the wire that I suspect the tacho is, the needle moved a TINY bit when I started the car but then sat at 0. Would this point to me needing a tacho booster Jim?

Thanks guys

Chris

[wilbo666]

I would have thought that the dash input would be high impedance....it is a modern dash that took a 12V square wave signal from factory....

a simple "buffer" circuit would be if really needed (if below makes any sense!...)

------------------ +12v
|
res (1k say)
|
FET (Drain)
MT signal-----FET (Gate)
FET (Source)
|
GND

Cheers
Wilbo

[sideshow]

not sure

i doubt that the microtechs even have a 12v signal out
as this would be enough to drive some tachos but most tachos will not work thru a microtech

i sold afew of these to dale he does abit of microtechs and he uses these for that purpose

and all the microtechs i wire up i usually have to fit these

new style tachos have such a variety of signals these days
thats y i carry 3 types of tacho boosters

even things like msds have a funny tacho output signal as this is not enough to get
some tachos to work even though they have massiv espark output they dont really have a good tacho output signal
this might be due to not wanting to damage and tacho circuitry

[mUnky-matt]

I'm resurrecting this thread because I have the exact same issue... I've got a 1jz running by microtech and I need the microtech tach output to power a jzx90 dash... i've tried powering the tacho and applying the mtech tach output directly to the signal terminal of the tacho and it does not work. Connecting the tacho sig terminal to one coilpack neg terminal produced a very weak tacho movement "maybe proportional" to the engine revs but only moving with a range of 0-300rpm for 1000-5000rpm shifts.

Any tips? Can't find any information on 'boosting' the signal or alternative methods of generating a tacho signal.