TACH WIRE INPUT

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Forum Name: Vehicle Wiring Information & File Requests
Forum Discription: Request Car Alarm, Car Stereo, Cruise Control, Remote Starter, Navigation, Mobile Video, and Other Vehicle Specific Wiring Info, Manuals, Tech Tips
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=4197
Printed Date: October 27, 2025 at 5:28 PM

Topic: TACH WIRE INPUT

Posted By: DL334
Subject: TACH WIRE INPUT
Date Posted: October 05, 2002 at 1:21 AM

Does anyone know about the tach wire input read. Do it read AC volt, AC pluse, and from what level does it read to how high. please help.

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DL

Replies:

Posted By: Montrealler
Date Posted: October 05, 2002 at 1:43 AM

its an alternative square wave

if you may be more specific for the use of this info i could perhaps help.

usually CAR STARTER OR CRUISE controll unit count the number of pulse that is read in a period of time

if your engine have only 1 coil and 4 cylinders and is turning 800 rpm

the tach will probably be 3200 pulses per minutes

1 full turn is 4 explosion so 800 turns x 4 firing = 3200 pulses for 800 rpm

for the voltage it vary a lot so must check to know

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Yes I'm Back 2006...

Posted By: SOUND PRESSURE
Date Posted: October 05, 2002 at 2:36 AM

Your tach wire should read between 1-6 volts.

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Sound Pressure

You know you have the right amount of pressure when your eyes start to water! Now you've got Juice!

Posted By: Glynn
Date Posted: October 05, 2002 at 5:13 AM

We usually set our meter to AC volts. Then look for a wire that sits around 1 to 4 volts around 800rpm. It should then increase smoothly as the rev's increase-as did the one today.

Friends VW Golf today sat at 4volts @800rpm. 7 volts @ 3000rpm.

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