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Old 09-10-2008, 12:02 PM   #5 (permalink)
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Join Date: May 2008
Location: South Dakota
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GMC Sonoma - '94 GMC Sonoma
90 day: 36.97 mpg (US)
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Originally Posted by pasadena_commut View Post
Where and how do you plug in a lead to pick up the fuel injector drive voltage?
I did it on my GMC sonoma 4 cyl. by finding the correct wire on the ECM under the dash. You can just use one of the two wires of any fuel injector. One of them will be hot when the engine is running and the other will be switched, i.e. pulled to ground by the controller. It will be a square wave with a varying duty cycle that varies depending on how much fuel is being asked for. It will not be a varying voltage in the direct sense but can easily be turned into a varying voltage for feeding to a comparator or anything else you wish to do with it.

Last edited by Gregte; 09-10-2008 at 12:12 PM..
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