One of the fuse links attached to the bus bar at the front of the underhood fuse box. I forget which one, but it is probably a 40A or 50A fuse link.
Have you checked (third time I have asked this) the glow harness CONNECTOR near the headlight?
It may look like this:
Or like this:
Depending on build date.
This is where the glow plug bridge (the plastic thing that actually snaps on to the plugs) is connected through the engine harness and attaches to the car's wiring, and then in turn goes to the glow control relay under the fuse box. You need to verify this connection is good, and all four wires (again, look at the wires on the harness for the colors... they are all black, with four different colored tracers) are good. This will at least split your potential wire problem areas in two... good/not good from the connector to the bridge, good/not good from the connector to the relay plug.
Check the fuse. Check the wiring to and from this plug. Don't post again until you have checked these things.