old thread but relevant to what I am dealing with.
on my current rendition of my 7.3 i totally ditched the controller, I had just the relay to the zd9 glowplugs, and a home made harness made out of 4 awg that tplits to two 8 awg feeder wires. ANyway the relay always made a squealing noise, tired 2 otehr ones same thing. truck always started funny (was fine before this whole experimentation).
tried wellmans-garbage they swelled 6/8 plugs
put a new western relay in last night, no squealing, but truck woudl not start this morning. tried shorting the GP feed wire to battery for 10 seconds, still nothing. ither my harness is crap or my 7 month old berus crapped out.
THey are under warranty so i ordered 8 new ones, as well as 1 autolite 1109, which will be here tomorro.
I have one old beru that reads about 8ohm, I will test it on teh battery charger with the 1109 tomorrow for 45 seconds see what happens. If the autolite passes, I will order the AC delco ones (if i can find them, )or more 1109s..

Maybe with my huge gauge wires, and proper relay I only need to glow the berus for 5 seconds or so in 30F weather?

PS started fine with no plugs last night with the block heater on for 1.5 hours. Few cranks and it was off.

the constant duty ones would be great as you can leave them on for 2 minutes to build more heat, and get less smoke out the pipe during cold starts..