Where does the RPM signal come from on a 7mgte?

[kemicalx]

G'day all,

Just trying to get my digital tacho to work again after installing my EMS, Does anyone know where the dash gets the RPM signal from? I thought it would get it from the CPS, but having checked the wiring i can see it doesn't. If it gets it from the ignitor how would i wire it back up now that i am using an aftermarket ignitor? I'm finding it a bit annoying having to glance down at my little EMS handcontroller while driving to see where abouts the engine is sitting.

Cheers guys,
Ashlin.

[BeRad]

the signal wire.

from the ecu to the ignitor, why not just use one of the outputs for it.

[CrUZida]

IG- output from the factory ignitor drives the tacho.

[ma61turbo]

You can also drive it from the check connector. That's where I'm driving my autometer tacho from, works a treat. There's just a receptacle(??) for a spade connector on the side of the check connector unit.

[CrUZida]

FYI - Thats all the same wire, it just bridges off.

[kemicalx]

K, so any ideas on how i'd wire it from an aftermarket ignitor?

[CrUZida]

Your EMS should have a tacho output on it.

Failing that you will need to build a circuit to take 3 inputs, and give 1 output.
The 3 inputs are the -ve coil pin on each ignitor (assuming you are using 3 ignitors?)
You should easily find this diagram on the web somewhere

[kemicalx]

Do you know which plug i should be looking at to find the IG- output that drives the tacho?



I'm presuming it'd be the far left one and I traced the IG- from the check connector back to a wire there. But i'm not sure if the tacho output my ecu creates will work with the standard tacho

this is the wiring diagram that came with the ecu

[JustCallMeOrlando]

The EMS doesn't have a tacho output does it? You might have to find that circuit which takes an input from each of the coils.

[ViPeR_NiPPleX]

squarish plug in the middle of that pic i believe.... might need to find a diagram

[kemicalx]

The EMS doesn't have a tacho output does it? You might have to find that circuit which takes an input from each of the coils.

Yep the tacho ouput is pictured above

[urantia]

I'm pretty sure its the one that carries the tacho signal is in the yellow plug on the far left (the long rectangular plug) it is a black wire if memory served me correctly)

[kemicalx]

yep it was a black wire on that plug that i traced back from the Check Connector