Batteries good, will baaarely crank. Starter/Solonoid/GlowPlug Relay???
So may truck is having a helluva time starting at any temp below 40. The starter will crank for maybe a second before I no longer have juice, then I have to throw a trickle charger on it. I'm in the southeast, so had no real reason to fish out the block heater plug until the last few weeks. If the block heater is plugged up for a few hours prior, it'll start, but only if I haven't attempted to start it already. Otherwise it's block heater + trickle charger, a bit absurd for a single night at 40 degrees. It past winters, it's started without assistance down in the mid teens.
No codes, and I can see the voltage initially drop for a couple seconds for the glow plugs, then return to roughly 12-14. No other electrical issues.
Any ideas? Or more accurately, what should I be checking to narrow it down?