2015 Silverado. Sometimes it starts fine, sometimes it won't. I have to turn the key off and on and it will start after 5-10 tries but it acts like the battery is low. Had it tested and it tested good. Any ideas? Hasn't started the last 3 mornings.

Check battery connections and ground connections, as a start.

Does it turn over at all or just a click?

Starter brushes would be my guess!

It only has 177000 miles on it!
It doesn't do anything. Not even click. But then it starts cranking and starts.

Starter may be going, could be an issue with the ignition switch also. Need to start checking what is and is not getting voltage.

Loose nut behind the wheel.

I'd guess a bad connection to the starter or bad switch.

This. I'm going through it now too, mine is no crank no start. Got the multimeter out and start with the battery, the ground, then working through the circuit. I'm terrible with the electrical stuff so I'm slow lol.

I took out the starter relay and it checked good. Then I made sure I had power to the relay and I did. So I made a jumper wire that I used in place of the relay which should have bypassed the ignition system and neutral switch and the starter should have turned over but didn't. So next I'll run a hot line down to the starter and I think that should tell the tale. But, like I said, I'm certainly not that great with the electrical side.

Yup. I'll start by cleaning battery connections.

Starter or bad connection.

Do you have another key to try- I had an ignition issue where it was hit or miss and ended up being anti-theft ignition switch not recognizing the key

They do have a problem with starters.

Just put an OEM starter in my 2015 GMC 2500 165 k

Original battery crapped out ..right at 5 years old..

And JUST changed the original brake pads (165k )

Might be a safety switch. either in the column or clutch if it has one.

Have a 2010 Colorado that will do that sometimes. Wait 10 minutes and it will start. Service garage had it for a couple days and said it was a security issue and to just wait 10 minutes if it don’t start and it will and has always started 😡

Pretty sure you know the reason. Was used too much when new.

Check the ground strap between the engine block and the body.

Wonder why they couldn't clear that in the computer. I just decided to teach myself how to understand the computerized vehicles and both the starting, charging systems. Got a fancy code scanner lol. When my old truck went down it took 5 minutes to diagnose it and 25 minutes to remove and replace the starter. These newer ones ain't so simple lol.

All the dang actuators, relays, sensors, it's ridiculous and I figure I best learn the circuits. By 2026 I should have a grasp lol.

I had a 1995 Chevy pickup, that did same thing.
It was the ignition switch, had new put in and was just fine after that.

Do trucks still have starter relay switches. Had one go out in the 70s.