Tacho signal from transmission?

[Mitsuru]

Can automatic transmission input speed sensor on a electronicly
controlled transmission be used for tachometer/rev-counter signal?

The reason I ask is on my engine swap the doner car's gauges all
went on a bus system and not separate wires.
The car the engine is going into has the wiring for separate gauges.
The speed sensor is coming off a sensor on the adapter part for the
transmission an will give the correct speed of the car.

But the rev-counter signal where to connect to get a good correct
signal! Someone suggested tapping into the input speed sensor on the
transmission.

The doner Vehicle was a 1998 Chrysler Voyager/Dodge Caravan v6 engine
and a 4 speed automatic transmission (41te)

Any help or suggestions welcome, and thank you in advance.

[Mitsuru]

There are a few different web sites with DIY versions oF the tach adapter.


Tachometer Installation

http://vstar1300.pbworks.com/f/TachAdapter.pdf

I have found after a little research a cheap tach adapter $10 plus postage.
This small board adapts a Tachometer to up to 4 individual coil packs, capable
of handling 4, 6 or 8 cylinder wasted spark applications



Installation is straightforward:

* Connect Coil 1,2,3 and 4 to the drive signals to each coil packs as necessary.
* Connect the tach output to the input of your tachometer.
* Wrap the board with electrical tape or shrink tubing- the board is small enough
to integrate into your wire harness / bundle.

Example Wiring



Here is the the web address
TachAdapter - Autosport Labs

I have purchased one from their website with paypal.
So I will try it when it gets here in about 2 weeks time.

This could be used on other vehicles for engine swaps etc.

[Mitsuru]

Okay as there was no real scale to the photo with the tach adapter.



And that is 15/16 of an inch.

TachAdapter - Autosport Labs

please look at my engine swap to see it get wired up.
Replacing 4pot with V6 in a Neon

[Mr. iNCREDIBLE]

you are trying to attach a tachometer for engine rpm?

typically you tap into an ignition coil for that I believe.

[moparmike610]

you are trying to attach a tachometer for engine rpm?

typically you tap into an ignition coil for that I believe.

tap into a coil or injector is what Ive always done

[Mr. iNCREDIBLE]

tap into a coil or injector is what Ive always done

me too, and transmission tail shaft for speedo, or now you can get a get speedo gears for older (pre 1980 usually) transmissions that convert the speedo gear output to electronic as opposed to a cable setup.

[Mitsuru]

With the above adapter it takes the signal to the ignition coils and turns it into a true rpm signal.
Coil packs are one coil for every 2 cylinders usually, so only tapping into one coul means you're
tach will be only showing a third of the true rpm.

As I have plenty of used insulin pens, and the cap/cover is
the right size I decided to use a bust one as a holder and
protector for the tach adapter.

I show an undamaged insulin pen next to the cap and
snapped off end how it will go together.
(the insulin cartridge was undamaged)





Almost done the below picture is before I used gasket
seal to glue and seal the bits together.