hotwheels000

5.0 build using a FiTech efi system so I no longer have the ford ecu...

I understand the tach wire is yellow/blu at the cluster and also in the diagnostics box. Can I jumper off either of those points straight to the negative side of the coil ?

Is a resistor required ?

Thanks in advance

engineer

Hi,

use the Dakota digital universal tach adapter us ethe fti as the trigger and the Dakota to drive the tacho in the dash. It does the 8 to 4 cyl conversion for you.

It saves a lot of mucking around.

cheers

hotwheels000

engineer

Hi,
Make sure that you are sending the output from the DD Tach Adpater to the correct wire at the cluster.

Wiring plugs at the back of the Mazda instrument cluster can be found as follows. Plug 1 is white, plug 2 is black, and plug 3 on 99-05 cars is small white. The tach wire is as follows:

90-93: 12v is 2K black/yellow, tach is 1H yellow/blue.
94-97: 12v is 2K black/yellow, tach is 1H black/white.
99-05: 12v is 1C black/yellow, tach is 2K green/orange.

Check to make sure that you signal output from DD is going to the correct wire in the cluster as per above.

If it is and its still not working then a pull up resister may be required.

Below is an exert from Flyin Miata on how to set up a pull up resistor into the tacho signal wire, although this is for a GM ECU it illustrates the point:


Tachometer mod. The Miata tachometer is expecting a different voltage input than the GM ecu puts out, so we need to fool it. A 2200 ohm (2.2K) resistor needs to be jumpered in between switched 12 volts (Mazda 12v wire listed below) and the tachometer input lead (white wire in GM bulkhead connector) going from the GM harness to the Mazda instrument cluster.

The white GM wire will connect to the Mazda tach wire going in to your instrument cluster (below). The 12v -> 2200 ohm resistor -> will “T” into this tach wire. An easy way to visualize it is to just think of the 2200 ohm resistor as a jumper wire between the 12v wire and the tach wire where it plugs into the instrument cluster. Make sure you cover the resistor with heat shrink tubing to protect it from shorting! What you’re doing here is “pulling up” the tach signal voltage so the Mazda tach can read it.

hotwheels000

Thank you for the additional info.

For the 92 model I had it hooked up as described less the pull up resistor. As a quick verification I bought a cheap tach and used it instead of the stock one. DD still would not send a signal to the cheap tach. Hooked the cheap tach up directly bypassing the DD box used its 4/6/8 cylinder selector switch and it worked perfect. I took it one step further and hooked up the factory tach bypassing the DD and as expected I saw double the RPM readings.

From all the above findings I came to the conclusion that the DD was defective from the factory. Summit is sending me a new one, I will update the post when it arrives with my findings.

Thanks again for your help

engineer

Ahhh OK...that would explain it...its a bit hard to get things working when you are using a defective device to begin with

Great to hear that Summit are sending you a new one.

The DD unit is pretty awesome....when it is a working model

keep us posted..

cheers