# Tach wiring issue. 87 z24i



## Pynikal (Dec 11, 2008)

so i have searched on here and looked threw 9 pages of search results and have not found the answer to my question.


what would i tap into for signal to the tach on this thing??? negative of coil??


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## zanegrey (Dec 5, 2005)

is this an after market tach or oem??

if oem take a look at the back of the cluster gauge and look for the plug in behind the tach..

the wiring harnes prollie has a wire for it already..


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## Pynikal (Dec 11, 2008)

its a aftermarket cheapy sunpro out of a old 69 z28 camaro.

free is the best.


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## CMax03 (Jan 17, 2009)

You may have to wire it all the way to the igniters!


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## Pynikal (Dec 11, 2008)

which is fine with me. i just need to know what wire to tap into for signal.


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## CMax03 (Jan 17, 2009)

Pynikal said:


> which is fine with me. i just need to know what wire to tap into for signal.


Break out your VOM and turn the ignition on but don't start it... and find your positive wire between the capactive igniter and the exopy coil. Use the primary coil for the signal which is on 100% of the time, if you use the secondary you will have a intermittent tach.


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## 87D21 (Jul 30, 2008)

Let me know what you find. I'm looking to put one on my 87 too.


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## bongo667 (Mar 2, 2009)

I recently did this on my 89 Z24. I may have done it the bass ackwards way but it is easy and accurate. There is a diagnostic plug behind the drivers side headlight, that has a Blue wire and a beige wire. I took the jumper out and added a plug to the tach read wire (green wire off tach) and plugged it into the diagnostic harness slot for the blue wire. Works like a charm and had it tested, so it is very accurate. I always remembered that most every older car/truck had a blue wire for a diagnotic plug so I looked for that and it worked. VERY EASY!! No problems what so ever. Good luck


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