There's a bug with the GP38-2 Union Pacific locomotive step lights. Switching on the step lights causes the rear left bodyside grille cover to glow, as if it is a light source. HOW TO RECREATE: 1. Start TSW4 > Choose a route > Peninsula Corridor > Timetable > On foot. 2. Select any start location and time. 3. Spawn at the chosen starting location and spawn a GP38-2 UP locomotive. 4. Enter the locomotive cab and switch on the step lights. 5. Switch camera to external view and look at the rear left bodyside grille. You will notice that part of the grille cover is glowing like a light source.
