One day the vehicle wouldn't start, I am a mechanic on the side for the last ten years, figured it would be no problem. Boy was I wrong.
So here is the deal: Cranks but won't start, no fuel pressure, no spark, no communication with scan tool, gauges aren't responding but they do work when you reset them (hold trip reset and turn key on).
All of my relays check good and have been load tested as well, no problems there. I have verified 12 volts and ground to ECM, continuity between grounds are good as well.
Now here is where it gets weird: 5 volt system?
-I am not getting 5 volts out of the PCM with the key on, only about .25 volts.
-If I unplug the sensors on that circuit I will get .63 volts
-When I turn the key off, I am still getting .33 Volts on the 5 volt circuit when I should be getting 0.
Now I know what you are thinking, easy you have a bad ECM, well it is a re-manufactured one that I just put in there because I was 99% sure it was bad too.
Am I missing something easy? Is the new ECM bad as well? Is there something wrong that fried the ECM and the new one?
Any input would be awesome, this vehicle is my dads and I have countless hours in to testing and diagnosing, I just want it fixed and out of my shop! Thank you!
Saturday, September 26th, 2020 AT 12:46 PM