I have a 1978 300d and my glow plug light stopped working so i replaced the glowplugs..... still no glow plug light and no power to glow plugs. I hear that there is a strip fuse on some 300ds but not mine....... i just have 2 ice cube relays under the cover on the fender. does anyone know about the 78s because it does not match up with other years.

 

Your fuse should be on the firewall near the brake booster.

 

I just looked and no fuse. I think that my car must be a 1977 that is what it says on the door panel. the only fuse that i see is a sand filled fuse link that goes to one of the little cube relays that is mounted on the top of the fender.