Hi--Thanks for all of the great sharing of information!

One day a couple of weeks ago on my 1980 300D, I had a flashing gp light on the dash and no start--not even crankable.

I took the opportunity to get the pencil style (large body) plugs, but wonder if it's actually the relay. Before I test the new glow plugs, I'd like to make sure I'm clear on a few points:

1. Disconnect the ground strap (at front of engine) from glow plug post
2. Use some heavy insulated wire to make jumpers between plugs (to replace the stiff wires)
3. Replace 50 amp fuse with 80 amp fuse? (necessary?)

And then I guess I'll see if my problem was the plugs or something with the relay; I'm thinking it might be the relay since I didn't get a crank. If that's the case, I'd be interested in a "manual" glow period with a switch on the dash, like Stevo--and so a 15 amp switch will be adequate?

Thanks!