Well as the (FNG) .. fricking new guy...I've enjoyed the comments and diagrams with the PCM and glow plug issues. I had the same problems with no power to the glow plugs.
I have a 2001 m1035. I decided to give building the box myself a try. I did make a voltage change to the glow plugs themselves. After reading that some of the glow plug problems were from overheating, I switched my build to a primary 24 volt solenoid and a 12 volt secondary (glow plug only) solenoid. I purchased the G60 glow plugs and a new stand alone glow plug harness from a diesel truck vendor (yes it has the spade connectors, but so do my new glow plugs. My idea was it works great on the chevy trucks why wouldn't it work here. ( I think I will need to hold the button for a few seconds longer but I will do a live glow plug test before I install to figure the optimum glow). Chevys don't seem to have the yearly problems of glow plug replacement, and swollen glow plugs. I do want the original look so I didn't want to add a solenoid under the hood, so I built the box with the wisdom of others. The box I used had circuit boards and wires inside. I saved the wires and trashed the boards. I also used the original wiring harness for the engine and under dash connections so other than the momentary push button it should look normal. I do plan on installing a blade fuses in both 24 and 12 volt wires going to the box, in the engine compartment .....just in case. I still need to add the diodes and wire the push button before a bench test. Not perfect, but hopefully functional .
It, like most things is untested so I will let you know.
What are your thoughts??