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1999 LS1 tach voltage

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Old 03-16-2015, 05:07 AM
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Default 1999 LS1 tach voltage

Im installing a fuelpump controller in my car and i have free usable wire from ECM which is suppose to go to tach. I dont need tach, so im planning to put tach wire to the puelpump controller. What kind of voltage tach wire is producing???

I need 0-5v to the controller.
Old 03-16-2015, 07:36 AM
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The tachometer wire is a class 2 serial data circuit and does not carry usable voltage.
Old 03-16-2015, 10:23 AM
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Thanks WhiteBird for information. You confirmed my expectations. Guess i have to pick my voltage from TPS wire. I dont have my harness connected so i cant measure, but i presume throttle closed its 0 voltage and throttle open is 5V. Can someone confirm? Would be nice to know when i soon order my controller.
Old 03-16-2015, 04:44 PM
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The throttle position sensor uses a 5V reference signal from the PCM but its output varies only from about 0.6V at idle to slightly above 4.0V at WOT.
Old 03-17-2015, 03:44 AM
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Oh man, that worrys me if i can get only 80% out of my controller that way.
You seem to have good knowledge about these electronics. Do you know where i can find good voltage to drive the controller and what kind of fuel controllers people are using here with success?
Old 03-17-2015, 06:49 AM
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Sorry, I don't know of any circuit in the car that gives you a full 0-5V range that varies with engine speed.



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