Possessed Glow Plug Light-New Relay!
 

I recently had to get a new glow plug relay for my '79 300SD. I now have the strangest problem. I know what it means when the glow plug light flashes for thirty seconds after a start, and the other fault indicators that the light gives, but...

Why on earth is my light flashing randomly for the entire time I'm driving my car???? From once every half an hour, to once every five seconds, to once or twice in a row, you get the picture. I almost thought that it happened only while running the heater, but soon proved myself wrong.

I wonder if I have a defective relay? Any ideas or experiences with this?

It's driving me crazy. Thanks!