Electrical Problem/Electrical Short
Whenever the ignition set to on there is only enough power to light the cab light.If I try to, for example, roll the window up or down all the power disappears and nothing works, when I release the button what meager power there is returns. When trying to start the engine all there is, is an electrical sounding clicking (not the solenoid). Have plugged in a tester and that doesn't work as it drains the power as before and just starts turning on/off rapidly. We've replaced the battery and it is good but still does this and we've tested all the fuses, all are good.
One peculiarity, don't know if it is supposed to do this, but when the battery is removed and a volt meter is put to the battery cables there is a fluctuating current. Also, with one post connected and we test between it and anything metal in/on the truck there is a steady current.
No idea what else to check. Need help bad as it is our only reliable vehicle.