Turn key and dash goes dark for 5 seconds before engine starts to crank

[Evan Martin]

SOLVED! Turns out it was just the starter relay. Swapped it with the trailer light relay and it fired right up, no hesitation. 

 

2018 3500 duramax LT. 130K

This happened on and off a few months ago, now it's starting to be almost every day. 

Get in, turn key to on for a second, then turn and holt to start. All the dash lights go out and nothing for 2-5 seconds, then the engine cranks over and fires up. A couple times now it has half started and died, then cranked again and started. 

My thinking is the started is having issues, but concerned it could be the ignition switch or something. 

We had problems with the ignition not unlocking with the OEM key (2 replacement keys seem to work fine) but we haven't used that key in over a year. 

Starter looks like kind of a PITA to install, but not terrible. 

Edited June 25, 2024 by Evan Martin
Solution

[CamGTP]

Usually a connection issue if all the dash lights go dark.  A bad starter shouldn't cause everything to go dark.

 

I tend to find problems with the battery cables or grounds. I'd be testing the cables and cleaning all the connection points you can find.

[Evan Martin]

This morning nothing. Turn key and it doesn't even attempt to crank.