Hey Ross,
So instead of soldering the negative wire to the positive then just run it to the negative on the battery and ground it somewhere on the engine or chassis. That was my idea, I just thought I had to run it through the positive wire as well as to the battery.
Thanks for the help I think I get it!!
So its + to the 12v source then to the glow plug & -ground to the engine mount.
Think thats it!!
Thanks again for the help and replies guys!
ORIGINAL: Ross Kean
I can't tell what you are planning to do from your diagram. It almost looks like you are running the ground wire back to the main lead. The main lead would have to go from the center post of the plug to one of the battery terminals. The other wire has to go from the other battery terminal to a grounding point on the engine. The circuit is completed across the glow plug element.
Maybe I have mis-interpreted your plan??
Ross