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Ok guys, electrical gremlin here. 2009 Mariner w/ 3.0L. 135k miles. Basics: High voltage pull from somewhere. When applying brakes coming to a stop, lights dim/flicker and tac goes a little crazy. While applying brakes and using power windows, can nearly kill the engine coming to the stop sign. Same thing sitting in park. Lights will flicker a little and while using power windows or any electronic with pull, lights dim severely, and engine hesitates quite a lot. I replaced original alternator and 4-year-old Walmart battery since that is likely going to be the problem. No change. Starts great, no codes, battery cable contacts all cleaned and shiny. I thought maybe the ignition switch or module since that is a known faulty area. While sitting in park with the engine running, I turned the ignition to "start" and hold it and low and behold, the electrical gremlin is gone. When I turn the ignition to start, it deactivates the interior lights, the dashboard, and possibly some other electronics, but it makes the car idle proper and the lights that remain on do not flicker. Does this sound like the starter pulling voltage while the car is running? Thanks!
 

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The circuit that is connected when in START also disconnects a bunch of other loads. I think including at least some if not all of those you mentioned. IOW, the flickering / crazy goes away when those items are taken off the circuit.
I think you may have a problem in power distribution. Th flickering when using the windows, lights dimming and engine not running properly could be the lack of electricity coming from one circuit and being supplied by another, or, if there is a disconnect problem, items in circuit can become the pathway for current to operate OTHER things.
I would get a circuit diagram and see the powers and grounds for the individual circuits. For example, using the power windows draws current from its supply, and either the lighting circuit is supplying(dim indicated voltage drop), or the ground is being routed via another route. Using a VOM you can check voltages on the circuit as the load is applied to different parts.
I would not turn the ignition to START when the engine is running unless I like to replace starter pinions or ring gears.
tom
 
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