CDD manual glow plug conversion 

I used a similar push button with a glow plug indicator light. It only lights up if the glow plugs are getting power, that's how I realized my stock glow plug relay was still trying to work, but not pushing enough power to trip the solenoid, my light was coming on every few minutes without my button being pushed😂

Classic diesel designs sells overpriced copy cat parts. Junk, spend your $ elsewhere.