What EDIS pins to use
Posted: Wed Mar 29, 2006 1:49 pm
To: Tony2ltr and/or Sevendriver
All EDIS Modules have an output called IDM , it's always pin-2 ,
this is a specialized output for comunicating with the Ford ECU .
It may or may not work depending on your Tachs input requirements .
I would never recomend connecting a Tach directly to your EDIS .
Here's why , the chip inside the EDIS that creates the output on pin-2
was designed to have a specific type of load attached to it and your
Tach has capacitors , resistors and diodes making up it's "Input Filter"
this filter may overload the output of the EDIS and smoke either
just the specific output you are connecting to or the entire Module ,
or it could even work OK , but cause the module to act strange or cut out
or who knows what .
It's better to play it safe and put as small of a load on these outputs as possible ,
which my circuit does , my cicuit also provides exactly what
ANY Tach wants to see on it's input , Plus 12volts or Ground .
I know that my cucuit works perfectly using the PIP Output .
4 cylinder EDIS modules have an output called CTO (Clean Tach Out) ,
I don't know anything about this output as far as directly driving a Tach ,
ALL of the EDIS signal outputs are designed to connect directly to the
Ford ECU , the ECU then provides outputs to other parts like the stock Tach .
I would imagine , because of it's name , that my circuit should work fine with this output ,
but I'm just guessing , I know it works with the PIP Output .
Here's some more info on EDIS :
http://www.dainst.com/info/edis/edis.html
Here's a quote copied from that page :
The IDM signal present on all EDIS modules is used as the factory tach output to the ECU.
This signal is used to determine the welfare of the ignition system.
If a coil primary opens or does not fire, the IDM signal is not emitted,
and thus the coil is faulty.
The IDM signal is triggered by the flyback voltage of the coil being fired.
The EDIS module processes this into a 512us pulse on the IDM line during operation.
When the engine is stopped, but the Key is turned on (KOEOff),
the EDIS module emits a 64us pulse every 262.144ms to indicate proper operation.
Because of this, any tachometer operation from this line must filter out the 64us pulses.
I hope this helps
All EDIS Modules have an output called IDM , it's always pin-2 ,
this is a specialized output for comunicating with the Ford ECU .
It may or may not work depending on your Tachs input requirements .
I would never recomend connecting a Tach directly to your EDIS .
Here's why , the chip inside the EDIS that creates the output on pin-2
was designed to have a specific type of load attached to it and your
Tach has capacitors , resistors and diodes making up it's "Input Filter"
this filter may overload the output of the EDIS and smoke either
just the specific output you are connecting to or the entire Module ,
or it could even work OK , but cause the module to act strange or cut out
or who knows what .
It's better to play it safe and put as small of a load on these outputs as possible ,
which my circuit does , my cicuit also provides exactly what
ANY Tach wants to see on it's input , Plus 12volts or Ground .
I know that my cucuit works perfectly using the PIP Output .
4 cylinder EDIS modules have an output called CTO (Clean Tach Out) ,
I don't know anything about this output as far as directly driving a Tach ,
ALL of the EDIS signal outputs are designed to connect directly to the
Ford ECU , the ECU then provides outputs to other parts like the stock Tach .
I would imagine , because of it's name , that my circuit should work fine with this output ,
but I'm just guessing , I know it works with the PIP Output .
Here's some more info on EDIS :
http://www.dainst.com/info/edis/edis.html
Here's a quote copied from that page :
The IDM signal present on all EDIS modules is used as the factory tach output to the ECU.
This signal is used to determine the welfare of the ignition system.
If a coil primary opens or does not fire, the IDM signal is not emitted,
and thus the coil is faulty.
The IDM signal is triggered by the flyback voltage of the coil being fired.
The EDIS module processes this into a 512us pulse on the IDM line during operation.
When the engine is stopped, but the Key is turned on (KOEOff),
the EDIS module emits a 64us pulse every 262.144ms to indicate proper operation.
Because of this, any tachometer operation from this line must filter out the 64us pulses.
I hope this helps