2011 GMC Sierra 2500HD, LML Duramax/Allison 1000.....Auction Rat, But a pretty clean truck! Came in on a hook with a no start (will not run written on the windshield)
Quick scan & view of some data showed a 5 volt reference being pulled low at 1.6 volts....I was visually inspecting the harness trying not to be to aggressive but still inadvertently unsorted the circuit. Finally found the short at the back of the A/C compressor after some more wiggle testing with the engine running (Caused the engine to stall).
2016 Ford F150 3.5L/6R80.....Also a Auction Rat, Runs the battery flat overnight.
I usually start with a amp draw measurement, But I've been trying to use my Thermal Imager more & it certainly saved some time.
The PCM power relay was glowing hot.
Bunch of DTC's in all the modules, Only 1 I felt was related to the issue.....U1012 Invalid data from ABS module. PCM is awake but the ABS module is not.
I took a short cut on this one as I remembered this issue on a different F150 of the same generation caused by corrosion in the Tailgate Harness connector. This one was full of water, But corrosion had not set in.
Cleared the water out & added some dielectric. Fixed!
Don't remember why this would cause the issue....The culprit stuck in my head because how bizarre it was.
Tore down & inspected a 2016 6L80E, Was at the beginning stages of converter clutch failure.
Bellhousing/Pump Body survived, Pump Cover/Stator had some light scoring.....Was able to clean it up in one pass on the lathe (.003" cut)