2011 gt500 swap tach signal

HCOR

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I've searched the sight the web and talked with MSD and Autometer to no avail. I swapped a 2011 gt500 engine and stock pcm into my 1986 notch, build the harness and it runs fine, tuned and almost everything works. I can not figure out how to get the tach to work. I tried an MSD DIS tach adapter it didn't do anything( I assume its good no one knows how to test them) tried the #25 pin on center plug of pcm thats posted for the 08/09 shelbys and that didn't work. does anyone know for sure how to make the stock 86 tach work with this engine/pcm?


OK UPDATE ----------------

PIN 25 does nothing on my pcm. not sure if that was earlier pcms or what. I hooked up MSD DIS tach adapter to neg side of coil and factory tach works at idle and upto 3000 rpms. once at 3000 it drops to zero until engine rpms fall back. any ideas? I, hooked off passenger side coil pack harness.
 
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SnakeBitten07

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Clean tach output. How did you add a wire, since the pin is missing? For the record, I did this and it works great.
 

SnakeBitten07

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No, I was able to run the wire directly to a tach and later a shift light. The output is setup for an 8-cylinder, so make sure your tach settings are set to that. Otherwise, you should confirm that the wire is getting signal from the PCM - you'd need an multimeter that can read signals, though.
 

69b302

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I hooked up MSD DIS tach adapter to neg side of coil and factory tach works at idle and upto 3000 rpms. once at 3000 it drops to zero until engine rpms fall back. any ideas? I, hooked off passenger side coil pack harness.

Give MSD a call on this issue. I had a similar issue(not on a GT500 however) and they sent me a inductive winding to put in series to make sure the tach could still see the ignition pulses. Fixed my issues anyway. Good luck.
 

HCOR

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Latest update 2/26 - retried #25 with and without tach adapter no signal for tach operation. i connected the red/green wire from the dis adapter to the purple wire on #4 coil and red wire to 12v ign source and the autometer tach works perfect, factory 86 tach still drops off at around 3k. called MSD agai and say it needs another adapter to amplify signal for stock tach. I should have that in a day ot two and will update after installing it.
 

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