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=40261
Printed Date: May 09, 2025 at 4:02 PM
Topic: Tach wire
Posted By: jkyliej
Subject: Tach wire
Date Posted: October 04, 2004 at 11:00 AM
Hey all, I was verifying the voltage output on my tach sense wire yesterday and found it to be 13.2 volts at idle. I thought tach sense wires were supposed to be reading 1-6 volts. Is this acceptable? I am working on a 98 Chev truck with a 5.7 vortec. White leading from coil. Thanks ------------- JKJ
Replies:
Posted By: jkyliej
Date Posted: October 04, 2004 at 12:32 PM
I also found a white wire leading from the "coil driver" that reads 0.89 volts at idle.????? Can you hear me now??
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JKJ
Posted By: saleen49
Date Posted: October 04, 2004 at 12:44 PM
you want the (-) side of coil for tach sensing or use a (-) injector wire which also works,
Posted By: jkyliej
Date Posted: October 04, 2004 at 12:53 PM
Everything I have read is that the negative side of the coil will read 1-6 volts at idle and on some Ford and Chevy's it is known they will read up to 8 volts. Obviously I am very far above and below those numbers. I will post a picture of the coil and the coil driver here shortly. The wiring diagram for this truck makes it even more confusing because the wire marked as "Tach pulse to gauge cluster" is the one I am getting 13+ volts from. The other white wire coming from the coil driver is labeled as a timing input for the vehicle control module. This one reads .89 volts at idle. I will have to test this wire again while I increase the enigine rpm's to see if it also raises as I did not yesterday.
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JKJ
Posted By: jkyliej
Date Posted: October 05, 2004 at 11:06 AM
The setting on the meter I use actually displays DC volts when testing. I have verified the setting the user's manual and also verified the readings by checking the voltage on the battery. I trust that I am getting the correct readings but just not the desired results. I have a picture of the coild and coil driver that I was trying to up load here but the file size is too large.
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JKJ
Posted By: mo12v
Date Posted: October 05, 2004 at 11:13 AM
U can also get TACH at Driver Front , White, Clear or Gray 32 Pin Connector Position # 9( White wire)
or Driver Front, ECM Red 80 Pin Position 10 (White wire)
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MO
Don't Learn from Others Mistakes
You Might Be the One That Knows.
Posted By: jkyliej
Date Posted: October 05, 2004 at 11:37 AM
I will say it again as well. The user manual has directed me to test this way. See meter. https://us.fluke.com/usen/products/Fluke+78.htm?catalog_name=FlukeUnitedStates If I test using AC volts I get nothing usable from the screen. Mo: can I send you an e-mail with pic and wiring diagram? ------------- JKJ
Posted By: jkyliej
Date Posted: October 05, 2004 at 12:02 PM
Bob: What do you mean. Do I need to go buy another multi meter? Does this thing work backwards or something. If it does I will toss it. There are too many other things to confuse me the last thing I need is a meter that works backwards.
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JKJ
Posted By: jkyliej
Date Posted: October 05, 2004 at 12:27 PM
Ok. I will test again in ac volts. I swear I wasn't getting didly from it when I did it the first time but I will try again. I know I have the right wire from the scematics just having a hard time verifying the correct voltage coming out of it to be 100% sure. I will reply again after I check.
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JKJ
Posted By: jkyliej
Date Posted: October 05, 2004 at 12:33 PM
10-4
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JKJ
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