I don't know ~ I've had one glow plug fail and cause the lamp to blink, another time the light didn't come on at all for one glow plug gone open circuit .

This presumes parallel glow plugs ~ the series ones you loose one plug it's the same as all = open circuit .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better