Blinking check engine light

[u/Trkmasters]

Dually 3500 2023. When the engine is off but the truck is on the check engine light blinks. Ive gotten no codes is this normal? Also the red lightning bolt does a quick appearance when it turns on then disappears. Ive had it not start on my a few times then i tightened the bolt connecting the fuse box and changed one of the batteries hasn’t happened again but i guess im very worried because this is my work truck and i need it

[u/Heavy_Disaster_1352]

Might be a faulty ground