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post #9 of (permalink) Old 07-03-2019, 06:49 AM
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Join Date: Jul 2014
Location: Concord, NC
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Originally Posted by Nexus9 View Post
Yes, Very helpful.
So the device (in this case, solenoid) is either off or on. The ECU does not vary the voltage or provide an opposing voltage that allows a variable current. The transistor acts as a switch (you said that the first time,I didn't really get it) which provides a path to ground.
So one way of measuring whether the solenoid is being activated (correct me if I'm wrong) would be to measure voltage from the green 12v wire from the "Open Collector Output" to ground. When the solenoid is off (not activated by the ECU), this should read near battery voltage, but when (if) it is being activated, the voltage between the incoming green and ground should drop to near zero, as it is being "grounded" at the ECU. This will definitely answer if I have an ECU problem or a cam installation problem.
Really appreciate both you guys taking time to help me understand this - I never really knew how the ECU controls these devices, and you probably helped a lot of other folks reading this thread as well.
By George, I think he's got it!

Good Luck,
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