I just love that glow plug light! Two days ago it was flashing after I started the car. Today, I checked the voltage on all of the glow plugs and all were getting 11 volts delivered while glowing. I checked the resistance on the coupler plug going to the glow plugs, and when I checked number 3 glow plug (actually the number 3 jack of the coupler), I had no reaction on the ohmeter. I pulled the glow plug, checked the resistance from the tip to the screw thread and still nothing. I replaced it, the light no longer flashed and the car once again started smoothly. It had been starting really rough after the light started to flash.

I love that light.