Glow plug light is not going out on initial start up, but when the engine is started when warm the light doesn't come on.The engine starts fine even when cold. I just drove the truck and when I turned the switch on the lights on the 2w/4w selector all came on momentarily. Any ideas? I bought it new and it has 94k on it. The only other issue I ever had was the speedo lost it's mind and I replaced the instrument cluster. Thanks, Ken