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2009 Challenger SRT8
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Discussion Starter #1
I did not see another forum that would be more appropriate to post this question so I will try it here.

I am going to buy a programmable RPM switch to activate something, and it needs a tach input. I am wondering if there is a external tach output somewhere ? 2009 SRT.

Thanks !
 

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There isn't, you'll need to install an adapter to get a tach signal for your device. Seems folks have come up with a couple of different ways to do this. Do a search for "tach signal" or "shift light" to see what's been done. Some have had success tapping into the coil signal (Not sure how since the coil fires twice per cycle) and I think some others have used an OBD-II adapter.

Good luck! :)
 

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2009 Challenger SRT8
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143 Posts
Discussion Starter #3
I looked up Raptor (shift light) and they use #1 coil signal. I have an 09 with 1 coil that fits down over 2 plugs so obviously it fires both plugs at once. You are saying on my 09 that it fires on the exhaust stroke as well (waste spark) as the power stroke? So that would make 1 pulse per revolution and be the same thing as a 2 cylinder 4 stroke motor as far as what I need to tell the RPM switch company. They list 4,6 and 8 cylinder applications. I guess it is not a huge issue as I can set it for a 4 cylinder and will have to do the math and figure out where I need to adjust it get it to respond where I want it to.
Thanks !!
 

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I would assume you'd have to set it up as a 4cyl or something like that, I haven't done this personally but I know the question has popped up in the past and there are a number of threads on this subject. :)
 

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2009 Challenger SRT8
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Discussion Starter #5
I took this (below) off the Raptor web site and it was for a 2011. I'll make it work one way or another.
Thanks

>>The cylinder setting must be set to "1 cylinder" mode since we will be reading from a single coil.>>
 
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