tach signal maybe wrong forum

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08-18-2003, 06:43 AM

wrx_pacman

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tach signal maybe wrong forum

does anyone know how the tach signal is outputted from engine?

is it an increasing voltage from say xx volt - 12 v?

or does the tach get it's reading in another fashion?

thanks

08-18-2003, 06:59 AM

Mulder

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Join Date: Nov 2002

Location: NYC

Posts: 1,646

Car Info: 02 WRX WRB

It's a pulsed signal, not a continuous voltage. The pulse frequency will vary with the engine speed. The tach signal is not available directly from the engine but only as an output from the ECU.

08-18-2003, 09:38 AM

wrx_pacman

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ah
i know my conquest w/ msd did a 12v square wave

wasn't sure about how subaru ran... one of my dad's old gms did it in a ramping voltage... aiight thanks