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Tach wire problems!!!!

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Old Mar 23, 2013 | 11:33 PM
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Default Tach wire problems!!!!

I lost my tach the other day in my 99 camaro after taking out the old LS1 and putting in a 408 LS2. Where does the #10 white pin wire lead to for the tach? My tach went in and out and now it just doesn't work but when i am tuning with my HP Tuners it shows my tach on the screen working. I was wondern if something has come loose or do i have a break in the wire. Please help!!
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Old Mar 24, 2013 | 11:40 AM
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Probably a break in the wire or a faulty connection..
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Old Mar 24, 2013 | 12:32 PM
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Can you just bypass the old wire by bridging a new one near pin #10, then connecting it to the tach?
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Old Mar 24, 2013 | 12:44 PM
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Originally Posted by gMAG
Can you just bypass the old wire by bridging a new one near pin #10, then connecting it to the tach?
I want to bypass it but don't know where the end leads to. I will Repin it but then need to know where that white wire goes to so I can hook it up.
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Old Mar 24, 2013 | 02:05 PM
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Moving from Gen3.
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Old Mar 24, 2013 | 02:14 PM
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The Tach Output Wire is PCM Red Connector, Pin 10, it goes through Connector C105 Pin G, that is the 8-pin Connector on the Wheel Well. Unplug both and use a Multimeter to check continuity, then go from there.

HP Tuners will show it cause it's running through the PCM.
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Old Mar 24, 2013 | 03:45 PM
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Mine did this as well I just switched to a ls3, with no wiring changes. Am going to look into it this week
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Old Mar 24, 2013 | 07:19 PM
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Thanks guys for the help
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Old Mar 25, 2013 | 03:10 PM
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Ok so i found the C105 connector. I have a white wire in the G pin coming in then nothing coming out the other side of the connector. From the factory it has been plugged. It's suppose to be another white wire coming out but it's not. How was i getting a tach signal before?
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Old Mar 25, 2013 | 03:20 PM
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the blank tach wire on the c105 connector goes to the traction control unit if you have one I believe. In my conversion I actually put a wire in that blank spot and ran a new wire into the dash harness and it works perfect.
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Old Mar 25, 2013 | 03:39 PM
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Originally Posted by six2eight
the blank tach wire on the c105 connector goes to the traction control unit if you have one I believe. In my conversion I actually put a wire in that blank spot and ran a new wire into the dash harness and it works perfect.
When u ran it into the dash harness what color wire do u remember hooking it to? Or how did u find where to hook it to? I will do that so i have my tach back again,
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Old Mar 25, 2013 | 04:48 PM
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The wire it seems to be is a gray wire by the IPC pin B6 Class 2 serial data is that seem right? But after I hook it to that wire still no luck...but my tach moves down when key is turned on
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Old Mar 25, 2013 | 05:09 PM
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my diagrams are at home, im work.... however, i just realized you are on a 99 and have a serial data wire. I did that to a 98 body with a 99 pcm. not sure if the tach wire is standalone or runs through the serial data wire. have you checked the wiring elsewhere to be sure it is intact?
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Old Mar 25, 2013 | 06:15 PM
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Ya I have tried to trace it down best I could. My PCM right now is a 2001 but my harness is a 2000-2001 cause a had a V6 and swapped it over to a V8. The weird thing is it worked on and off till just a few days ago
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Old Mar 25, 2013 | 11:18 PM
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That's the only Tach output..I've broken down a few of these. It may go into the BCM and then go from there..given how the factory programming is set to a 4cyl pulse.
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Old Mar 27, 2013 | 12:29 PM
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Switch the outer 2 wires on the cam sensor harness. If they are wrong the tach will not work or work intermittenly
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Old Mar 27, 2013 | 08:23 PM
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Forgot to put, that is exactly what I did and the car runs great and the tach works perfect
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