SOLVED: JZA80 2JZGE Tacho vs 2JZGTE Tacho (Engine Swap)

[wilbo666]

Does anyone know what the specific differences between the tacho's is? (JZA80)

I've come to the conclusion that the 2JZ-GE tacho works off voltage spike off the coil -ve, but checking the wiring diagrams it doesn't look like is the case, unless the igniter 'tacho output' (EXT) is simply connected to the coil -ve (C-) pin internally...



Does anyone have pictures comparing the rear of NA to Turbo tachos?

I've done a NA -> Turbo engine swap and would like to get the tacho working...

I could just fit the tacho booster I have (Which I've tested, and it does work), but if there is a simpler, more elegant solution (like changing some component values on the PCB etc) I'd rather take that option!

Yeah a 10k TRD tacho is an option too...

I'm pretty electrically savvy btw

Cheers
Wilbo

[CrUZida]

There were a couple of tutorials floating around a couple of years back that detailed how to converted an MX83 tacho to work with 7MGTE.
I'd say someone pulled apart a GX81 (1GGTE) tacho and compared the two.

From memory you needed to change 3 components to get it to work.

[thechuckster]

am stunned that the NA jza80 tacho is not 5v driven?

[wilbo666]

I'm also quite surprised, and annoyed

Btw the igniter output is +12V not 5V

Cruz, I know they one you're talking about, but I'm not having much luck finding it atm

Cheers
Wilbo

[DrNick]

I knew I had seen this somewhere before

Took me a good half an hour to find the thread on clubna-t but here it is. I can't take any credit for this, it was written by 'captdale'. I hope it helps somewhat !

HOw to mod a NA tach to work with a TT ECU/Igniter
Take out the tach and look at the circuit board. See the 33K ? resistor on the top right hand corner. Jumper the resistor with a wire. Put it all back together. Hook up the wire from the TT Igniter A1 terminal (ext) to the blk/wht wire on the Diag connector (tach) and your good to go. Does not cost one dime and works just fine.

Apparently the NA tach takes a high level signal developed by the distributor/Igniter circuit. The TT ECU and Igniter put out a low level signal for the tach. The NA tach current limits its high level signal by putting a 33K ? resistor in series with the input. When you jump the resistor the tach is no longer current limited and the low level signal from either the TT ECU (A16) or the TT Igniter either one will drive the NA tach just fine.

[wilbo666]

Interesting, will have to give it a go...!

Thanks!

Btw supraforums lol

Cheers
Wilbo

[wilbo666]

Reducing the series resistance of the tacho signal input works.

The circuit simply has the 43k resistor leading directly to the F->V converter IC, no voltage divider or filter circuit that I could see as well it is worth mentioning.

My tacho (JZA80 NA) had a 43k Series resistor, I dropped it down to ~100Ohms (100Ohm resistor in parallel). I thought it was safer to at least leave some current limiting.

Tacho works

Haven't checked accuracy, but seems close enough.

Resistor in bottom left of pic



Cheers
Wilbo

[teamdrinkalot]

I could just fit the tacho booster I have (Which I've tested, and it does work), but if there is a simpler, more elegant solution (like changing some component values on the PCB etc) I'd rather take that option!

Yeah a 10k TRD tacho is an option too...

I'm pretty electrically savvy btw

Cheers
Wilbo[/QUOTE]

So a tachco booster will work? My 2jzgte ecu will not drive my hiace na tacho. The microtech did, that was in it.

[wilbo666]

So a tachco booster will work? My 2jzgte ecu will not drive my hiace na tacho. The microtech did, that was in it.

Yep, tacho booster is the other option if you don't want to look at taking apart the dash.



Cheers
Wilbo

[midnight_purple_GA70]

Reducing the series resistance of the tacho signal input works.

The circuit simply has the 43k resistor leading directly to the F->V converter IC, no voltage divider or filter circuit that I could see as well it is worth mentioning.

My tacho (JZA80 NA) had a 43k Series resistor, I dropped it down to ~100Ohms (100Ohm resistor in parallel). I thought it was safer to at least leave some current limiting.

Tacho works

Haven't checked accuracy, but seems close enough.

Resistor in bottom left of pic



Cheers
Wilbo

ok so ive just completed a conversion from a 2jz-ge 5speed to a 1jz-gte 5 speed with a microtech...

just wondering if this resistor is the reason why the tacho doesnt appear to work off the microtech tacho output wire? although at this stage im not certain about my rpm signal wire heading to the dash...

Wilbo do you happen to know which is the tacho signal feed wire in the passenger footwell so i can just connect the 2 in case ive picked the wrong one...

[wilbo666]

just wondering if this resistor is the reason why the tacho doesnt appear to work off the microtech tacho output wire? although at this stage im not certain about my rpm signal wire heading to the dash...

Yep, that'd be the reason...

Wilbo do you happen to know which is the tacho signal feed wire in the passenger footwell so i can just connect the 2 in case ive picked the wrong one...

JZA80 is Pin 29 (Black, white stripe wire) on Plug II1



Cheers
Wilbo

[pandaah]

+ rep cos your a genius... lol good info to know!

[teamdrinkalot]

Hey Wilbo, will this work for me. I tried your PNP, NPN, Zener, Back Emf, Eddy Current gizmo cicuit to no avail. Tacho is the only thing not working - not that I think I need one.

[wilbo666]

Hey Wilbo, will this work for me. I tried your PNP, NPN, Zener, Back Emf, Eddy Current gizmo cicuit to no avail. Tacho is the only thing not working - not that I think I need one.

I'd give it a try for sure.

Just trace the circuit back from the tacho input on the dash and see if there is a series resistor would be the first start.

Cheers
Wilbo

[jzk25]

Epic bumpage. Just tried the resistor bypass method on Millsi's 1UZ Hilux tacho which is receiving a V8 low voltage signal from an M&W CDI. Worked straight up, just had to trim the pot to get the signal spot on. Massive win.