I have my glow plugs on push button and I like it that way instead of with the key. But there was one time I lost all of my glow plugs they all burnt out. Stuck on solenoid?? don't know. But after I replaced all my glow plugs I added a little LED light in the dash board right above the WTS light. When there is power to the plugs there is power to the light, kinda like a warning light. Two days ago i went to start truck ran the glow plugs started truck and my LED light was still on, I hit the button again and it shut off. I think my $8 LED light saved a set of glow plugs.