12 volt to 0.5 volt

[frank mc]

hi guys i looking to put something together to replicate this, ign 12v feed switches to 0.5 volts for 10seconds, then switches back to 12volts every time key is turned on.
any help much appreciated

 

[MikeMl]

Why 0.5V (instead of 0V)?

 

[frank mc]

0.5v is what the ecu needs to see before activating another program

 

[MikeMl]

0.5v is what the ecu needs to see before activating another program

would 0.65V (forward voltage of a Silicon diode) do?

 

[frank mc]

thats way above my pee brain, could you explain how it would work

 

[MikeMl]

This should do it. I dont know what the input resistance is to the ECU; I guessed 10KΩ. If it is a lot lower than than, we have to adjust some resistor values. Maybe you could measure it with an Ohmmeter, key off. See what it reads from the ECU input pin to ground.

The input to the circuit is the switched 12V through the key switch. That is on the right side of the schematic. The output is the presumed 10K input to the the ECU, on the left side.

The green trace is the key switch, and the red trace is the input to the ECU. If the input resistance to the ECU is much lower than 10K, then R7 and R2 will have to be adjusted. Let me know.

 

[frank mc]

mike i'm sure its been said before many times, maybe never in irish Go raibh maith agat (THANK YOU)