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2001 audi a4 problem started with air intake temp low voltage code. Ohm tested sensor, everything in spec. In Vagcom air intake temp reads 143C. Sensor plug is getting 2.9v to 4v. Checked every other 5v sensor same exact voltage. So my question is if I probe the back of the ECU plug at any 5v sensor pin and get low voltage, is it safe to say the 5v regulator in the ECU is the problem? Thanks
Does a diagram show what is on the 5v circuit where you could unplug all of the sensors one at a time to see if the full 5v is restored? I'm not sure if that situation would result in these numbers though?
Power at ecm almost exact as putting meter directly on battery. Checked grounds with multimeter and power probe. Unplugged sensors one by one voltage doesn't change. Noticed as i was retesting everything key on for more then 5min, voltage is only at 1.93. Is it possible with the ecm having power to it for a length of time cause the voltage to drop?
I like what Paul said in one of his videos on testing ECMs. Something about how you're never 100% sure on condemning a computer so you want to feel confident that you've eliminated all of the other possibilities.
Just cut wire at pcm where 5 volts comes out where you can fix it after. If still low reference voltage. Use test light check powers and grounds if there good pcm is junk
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