No light for glow plugs usually means you have glow plugs that are burned out. You should check several things.
1. You need to test all your plugs with a ohm meter. Test them for resistance. If you get much resistance on one put in a new one.
2. You also need to check that the relay is getting juice from the battery.
3. Check the strip fuse in the relay. Make sure it has no cracks. Check the resistance on it too.
4. Check all the wires going to each glowplug fro resistance, to make sure they are all getting juice.

That hopefully will solve the issue.

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