2015 EcoDiesel. Service 4WD message and only get a faint click when I attempt to start

[Zappaddles]

2015 Big Horn EcoDiesel with103k +- miles. New crate motor 5k miles ago. Rarely use 4WD and then only gently. Turn the ignition and only get a faint click. A poorly tightened main engine ground recently left us stranded until the problem was found and fixed. This problem seems to have the same symptoms as the loose main engine ground but I can’t find the ends of the other ground leads to verify their connection. A small red light appears by the service 4WD message. Before this truck is towed I want to exhaust any possible potentially simple solutions such as faulty or loose connections. Any clues? Thanks

 

[rule18]

I moved this thread into the 4th Gen area for you.

 

[indept]

Have you measured the battery to see if it's charged & checked connections on it? Also check connections at the starter. Since it's clicking it sounds like the start signal is getting to the starter so you would think its got to be the battery, cables from battery to starter or the starter itself is bad. That's assuming the grounds you mentioned are good.

 

[crash68]

^^^ what he said
Check the battery voltage with a meter both static and when trying to crank the engine.
If the battery is still the original, it's most likely time for a new one. It's a H8 size AGM type battery with a minimum of 800 CCA.

 

[Zappaddles]

Battery is new and hot as a fire *******. I’ll go back under tomorrow to try and find all of the ground connections. Thanks

 

[Zappaddles]

The code reader that I rented showed a UO100 code. Any thoughts?