Aftermarket Tachometer in a Sunbird

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Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=30635
Printed Date: July 18, 2025 at 12:13 PM

Topic: Aftermarket Tachometer in a Sunbird

Posted By: Powers
Subject: Aftermarket Tachometer in a Sunbird
Date Posted: April 18, 2004 at 11:23 PM

I just bought a new Power Fist Tach from Princess Auto (It was cheap and my friend has one that works very well) except when I get it all wired up, my car supposedly only idles at 500rpm and when I have the car reved right up the highest it will go is about 2500rpm. I'm pretty sure this isn't right. Does anyone know if I may have done something wrong, or what could be wrong with it that it's not reading right??

Replies:

Posted By: rallysport
Date Posted: April 19, 2004 at 12:46 AM

is your sunbird a v6? if so maybe you have it set to 4 cylinder mode which would read only 2/3 of your acctual idle so hence 500 instead of 700-800 posted_image

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Posted By: Powers
Date Posted: April 19, 2004 at 8:04 AM

No, it's the 4 cyl and it's set on 4 cyl...

Posted By: rallysport
Date Posted: April 19, 2004 at 11:41 AM

i think i had that backwards i meant 4 cyl set to 6 cyl mode, anyway there should be 2 white wires coming out of the ecm, one is "second gear in" and the other is the tach singnal, try swapping to the other white wire.

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Posted By: Powers
Date Posted: April 19, 2004 at 2:28 PM

OK, because I had mine attached to one of the white wires coming out of the ignition module, the same one I have my alarm attached to. Then I switch to the black one, and it's doing the same thing. On my ignition module there are 2 white wires, a black wire and a red and black wire.

I changed it through 4 6 and 8 cylinders, that didn't make a difference.

Posted By: rallysport
Date Posted: April 19, 2004 at 11:29 PM

so you switched from a white wire to a black one? try the other white one if you havent allready

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Posted By: Powers
Date Posted: April 20, 2004 at 11:29 AM

OK, I looked again. There are 2 black wires, 1 white wire, and a red w/ black stripe coming from the ignition module. The white only reads half the actual RPM. I'm sure it has to be a white wire. Someone said that there are two white wires by the ECU. I tried a bunch of wires, but only 1 worked, but still had the half RPM problem.