Tach Wire
Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=6862
Printed Date: July 30, 2025 at 1:06 AM
Topic: Tach Wire
Posted By: dfiddy
Subject: Tach Wire
Date Posted: December 18, 2002 at 6:59 PM
Just wondering how you'd go about finding a tach wire without probing and risking blowing a module. Thanks in advance for any info...
peace
Replies:
Posted By: jrilla
Date Posted: December 18, 2002 at 8:24 PM
You could just grab the one in the wire diagram as long as you know that you are grabbing the wire you know is exactly the one the diagram is referring to.  ------------- J Rilla
Owner/Installer
Posted By: JWorm
Date Posted: December 18, 2002 at 9:31 PM
yeah....what he just said works, but only when it works 
Posted By: Phatmex
Date Posted: December 18, 2002 at 10:05 PM
That's not always true dude. I've had more than one wire with the same color pattern running through the same place with different functions. Damn that pisses me off....
Posted By: installa
Date Posted: December 18, 2002 at 10:49 PM
you can always get tach at the injectors, ALWAYS!! there are 2 wires on each injecter one will be common color to all the other injecters, and one will be different, at any injecter take the color that isn't common to them all
Posted By: dfiddy
Date Posted: December 18, 2002 at 11:04 PM
Your guys' posts really helped me out...thanks eh!
peace
Posted By: jrilla
Date Posted: December 19, 2002 at 8:19 AM
If you have a particular car in mind I am sure someone on here is familiar with the car and could tell you. But if you are referring to cars in general, there is no reason for anyone not to test using a DMM. I can understand if you have one car and dont want to buy a DMM even though you could buy a $25 radioshack model that isnt great but it works. let us know more information if you have any
-------------
J Rilla
Owner/Installer
Posted By: Velocity Motors
Date Posted: December 19, 2002 at 9:00 AM
Just to add to this post, watch out for those cheap DMM's because they may not always give you the proper voltage in AC mode. Spend a little more and you get a little better quality.
-------------
Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
Posted By: dfiddy
Date Posted: December 19, 2002 at 5:25 PM
I do have a DMM but am not to familiar how to use it entirely...where would I hook it up and what reading should I look for? With the right reading how do I know for sure it is the tach wire?
Thanks...
peace
Posted By: jrilla
Date Posted: December 19, 2002 at 8:43 PM
Put the meter to AC voltage, put the red lead on 12v+ and the black lead on the target wire. you should get a reading between 1 and 6 volts AC and it should increase when the gas is pressed.
-------------
J Rilla
Owner/Installer
Posted By: TTopStang
Date Posted: December 19, 2002 at 10:39 PM
PLEASE TELL ME I’M NOT LOSING MY MIND!! Work with me here. You have two voltage options on a meter AC/DC (also a great band). AC is Alternating Current and DC is Direct Current. DC is used in applications where the current direction is fixed in one direction such as a battery and AC is used in applications where the current is switching directions such as in homes. I’m correct so far, right? Why then, do a lot of people, in numerous places, state to set the meter to AC when working on their car when it should be DC? Are you just playing a little joke on these people? If so, I’m sorry to have spoiled the joke, otherwise, I’ve lost my mind and maybe someone can teach me again.
Posted By: JWorm
Date Posted: December 19, 2002 at 10:52 PM
TTopStang, a tach signal is AC. The output of an amplifier is also AC. A car is not 100% DC.
Posted By: TTopStang
Date Posted: December 19, 2002 at 11:14 PM
Thanks JWorm. It's all starting to come back to me. Now where did I leave my keys?....LOL
Posted By: Velocity Motors
Date Posted: December 20, 2002 at 7:52 AM
Here is a thread from another member about this topic: How to use a DMM ------------- Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
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