Tacho signal from alternative source

[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.

[jimmyybob]

Tricky one this as the trans has input and output sensors for the trans and one driven from the driveshaft (as you would expect) but they all go into the gearbox ECU for processing.
You should have three wires on the driveshaft sensor Ground-Power-Signal the signal should be a white/orange wire. i cant find any details for the signal type.

[Mitsuru]

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


http://www.gadgetjq.com/tach_install.htm

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
http://autosportlabs.net/TachAdapter

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.

[jimmyybob]

Looks interesting, i wonder how it knows what kind of input your tacho requires.??? maybe they all work the same.?

[Mitsuru]

The car is made by Chrysler or should I say Dodge if you're American.
If you read the details of manufacturers instructions for aftermarket
rev-counters they usually state that the tach signal is the same if it's
4, 6 or 8 cylinder.

I can only amuse it is for some way of using a standardised unit in all
the cars and trucks, in order to keep costs down.

[Mitsuru]

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



And that is 15/16 of an inch.

http://autosportlabs.net/TachAdapter

please look at my engine swap to see it get wired up.

http://www.practicallyclassics.co.uk/vi ... 829#p15829

[Mitsuru]

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.