Hello. I have a 94 f350 7.3 idi I have the glow plug solenoid whit wire unhooked and a wire going from the post to a switch to ground in the cab. Went to start today and had no glow plugs. Checked and every one is burnt out. They are only 5 months old. The solenoid still clicks when I push the button. What would have caused this? I don't want to replace them and have them burn out again. Any help appreciated?

 

What brand of plugs do you have?