Hi Jim, my name is ***** ***** you for asking your question, I will try and help you out.
ECM's having intermittent issues like this do occur but most times its the truck wiring issue not supplying key power to wake up the ecm and allow engine to start,,,this is confirmed by no codes in system and light not coming on.
The 40 degrees temps won't be the issue so we can eliminate that now.
This sounds like a ignition switch or the wiring from ignition switch to the ecm.
The most common areas that create this problem are the pass through connectors going from inside cab to engine fire wall,
I take and disconnect all plugs on engine side since all are exposed to the weather and the ones that corrode first,look at each pin for any damage or green corrosion,,if you find any green on pins the pins need replaced,,,you can clean for now to get you going but the seals are bad on plug so replacement is needed.
Since this is a intermittent issue it makes it hard to duplicate but if you could get a test ecm from a dealer to swap out when you are having this issue is the only way to know for sure its a ecm issue,,I would hate for you to spend the money and have the same issue. So clean all plugs first then replace ignition switch since cost is cheap before getting a test ecm.
You can use any 60 series ecm that has the same plugs for testing,, so even a scrap yard one will work for testing.
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The question will still remain open for follow up questions if needed.