This video covers some key fundamentals that every single technician needs to learn.
What do you do when you find 0 volts on a position sensor signal? How do you force an output solenoid to energize? What is the purpose of the 5v reference and what to do when it is missing?
Are you confident enough in your troubleshooting to make a call on a bad engine computer? Even if that computer costs thousands of dollars?

00:00 - P1406 EGR Valve Position Sensor Circuit Problem
00:20 - EVP signal is fixed at 0 volts
01:10 - how to identify a power or ground side controlled output circuit with a voltmeter
02:20 - energizing an output with an ammeter
03:25 - how to force an electronic EGR valve to open to verify flow and EVP signal changes
04:40 - testing the EVP sensor (potentiometer) with a voltmeter
05:18 - missing a 5v reference to this sensor
06:52 - using a wiring diagram to identify the 5v reference circuit design
08:00 - measuring the 5v reference at the ECM
09:30 - how to check for a spread apart computer connector terminal (pin drag test)
12:27 - jumping the 5v reference circuit to fix our open circuit
14:30 - retesting the EVP sensor with a repaired 5v reference circuit
16:00 - bad engine computer confirmed

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For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
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Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.