How to test a Hilux 4wd Tacho ?

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How to test a Hilux 4wd Tacho ?

Postby OZ38 » Sun Sep 18, 2016 12:49 pm

Gidday,

Ok not sure if this is in the right place (move it if needed).
I have a '90 Hilux extra cab 4wd which originally had a 4 cylinder petrol engine (22r I think they called it). The Hilux has had a Marks 4wd adapters V6 ecotec conversion done on it.
I am still trying to get the Tacho working. As the Marks adapter box for tacho doesn't seem to be happening for me.

When logging with TunerPro I have a tacho readout so the V6 engine side seems fine.

So I have found the black wire that the original single coil from the 22R engine used to send its signal to tacho.
Now my question (finally some would say).

Is there some sort of test device/equipment that could be hooked up to this wire so I can test if the original Hilux tacho is still working ?
Auto Sparkies ?

Cheers

Deek

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Re: How to test a Hilux 4wd Tacho ?

Postby immortality » Sun Sep 18, 2016 1:19 pm

You would need some sort of signal generator switching from 12v to 0v should do it.

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Re: How to test a Hilux 4wd Tacho ?

Postby OZ38 » Mon Sep 19, 2016 2:59 am

Yeah, hoping someone will chime in with info about such a set up for testing.

Cheers

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Re: How to test a Hilux 4wd Tacho ?

Postby psyolent » Mon Sep 19, 2016 6:51 am

normally tachs are negative pulse, my 5 litre hilux still has the 22R tach in it but reads double ironically.
like immo mentioned, you'll need something to switch negative to the tach

i found this ; before you go ahead someone with more electronics nouse than me needs to sanity check this please. so don't go ahead yet.
ps: if you need a spare I think i have a spare hilux tach at home from a heap of shit i wrecked out - can't confirm if it worked though mate.

How to Check Your Tachometer

I was doubting my tach and was wondering how to test it to see if it is actually accurate. On the alt.autos.rod-n-custom newsgroup from 2001 (used www.dejanews.com to search), I found a discussion that talked about using a 12 volt battery charger to check the tach. So what the heck, I tried it.

The theory goes that a 120 Vac 60 Hz battery charger puts out an imperfect DC voltage. It is actually a pulsating DC voltage that corresponds to

* 1800 rpm for an 8 cylinder,
* 2400 for a 6 cylinder
* 3600 for a 4 cylinder

Well it works! When I hooked it up to my tach's input (+ve to tach +ve and -ve to gnd), it showed exactly 1800 rpm. The technical theory goes like this. The battery charger doesn't put out a DC signal, it is a 120 Hz full rectified waveform. When a battery charger is connected to a battery, the battery acts like a huge capacitor and smoothes out the waveform (simple explanation). I used a frequency counter to verify that the battery charger was putting out 120 Hz.

Here's the math:

120 Hz = 120 cycles/sec

120 cycles/sec * 60 = 7200 cycles/min

There are 8 cylinders, so 7200 / 8 = 900 cycles/min

but it is a 4 stroke engine which only fires on 1 firing stroke (combustion)

It fires once every 2 cycles

So 900 cycles/min *( 4 strokes/1 firing stroke) * (1 firing stroke/2 cycles) = 1800 cycles/min or 1800 rpm
Cheers,
Greg aka Sir Burnie Tanington

VX1 Berlina V6, VT1 Berlina V6 (Track), VN1 S V6, Hilux RN105 GMV8, Ford XP 170.

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Re: How to test a Hilux 4wd Tacho ?

Postby immortality » Mon Sep 19, 2016 7:51 am

Interesting theory but don't we use 220 volt 50hz in Australasia?

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Re: How to test a Hilux 4wd Tacho ?

Postby psyolent » Mon Sep 19, 2016 7:58 am

we do but the theory still holds......remember they are using a battery charger outputting 12vDC...........
Cheers,
Greg aka Sir Burnie Tanington

VX1 Berlina V6, VT1 Berlina V6 (Track), VN1 S V6, Hilux RN105 GMV8, Ford XP 170.

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Re: How to test a Hilux 4wd Tacho ?

Postby MAGP » Mon Sep 19, 2016 8:18 am

immortality wrote:Interesting theory but don't we use 220 volt 50hz in Australasia?
Australia has moved to the European 230 +/- 5% Volts in order to enable Australian consumers to safely use electrical goods made for other markets. Manufacturers don't make the old 240 volt parts for Australia anymore.

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Re: How to test a Hilux 4wd Tacho ?

Postby immortality » Mon Sep 19, 2016 8:27 am

It wasn't so much the voltage but rather the frequency of which I was fairly sure was 50Hz instead of the US 60Hz.

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Re: How to test a Hilux 4wd Tacho ?

Postby Dylan » Mon Sep 19, 2016 8:34 am

Yeah 50hz over here.

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Re: How to test a Hilux 4wd Tacho ?

Postby OZ38 » Mon Sep 19, 2016 9:47 am

psyolent wrote:normally tachs are negative pulse, my 5 litre hilux still has the 22R tach in it but reads double ironically.
like immo mentioned, you'll need something to switch negative to the tach

i found this ; before you go ahead someone with more electronics nouse than me needs to sanity check this please. so don't go ahead yet.
ps: if you need a spare I think i have a spare hilux tach at home from a heap of shit i wrecked out - can't confirm if it worked though mate.

How to Check Your Tachometer

I was doubting my tach and was wondering how to test it to see if it is actually accurate. On the alt.autos.rod-n-custom newsgroup from 2001 (used http://www.dejanews.com to search), I found a discussion that talked about using a 12 volt battery charger to check the tach. So what the heck, I tried it.

The theory goes that a 120 Vac 60 Hz battery charger puts out an imperfect DC voltage. It is actually a pulsating DC voltage that corresponds to

* 1800 rpm for an 8 cylinder,
* 2400 for a 6 cylinder
* 3600 for a 4 cylinder

Well it works! When I hooked it up to my tach's input (+ve to tach +ve and -ve to gnd), it showed exactly 1800 rpm.

Ok so positive to tacho positive & negative to ground ?
I am assuming the one little black wire that the 22R coil was sending its signal is what we're calling the tach positive ?

Can I possibly fry the whole hilux dash or more trying this in the ute ?
Even if it shows a different rpm level to what is above, at least it will tell me it is a working tach correct ?

Cheers

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