Here is my problem. My 93 300D 2.5 Turbo will not start. The glow plug indicator light on the dash does not light when turning on the ignition. I have tested each of the 5 glow plugs with a test light and they are functioning perfectly. I then replaced the glow plug relay with a brand new one ruling out that possibility. I checked the hot line going to the glow plug relay, and it (red wire 12v) is supplying power as expected. I am puzzled.

What could be preventing power from getting from the glow plug relay to the glow plugs?

Any ideas would be greatly appreciated.

Thanks,
Roy