No WTS (Wait to start) light

Hi, just started to have this problem. It wouldn’t start one night then started that next morning and now, it started the other day and I drove it to the gas station back and did fine. It will try and crank over but nothing. The glow plugs aren’t heating up and I do not know what else to do. I’ve checked all fused and secured my grounds on my battery and firewall tight to remove any corruption.
Thanks for all help ahead!

Best regards, Mason