By ground signal, I mean the PCM activates a path to ground. Thats common PCL logic control used everywhere from manufacturing industry to aircraft to in this case automotive. Post activation switching (activation after the load) reduces the total wattage flowing thru the logic board thus reducing heat. But what would I know, only went to 6 years of schooling for electronics and Navistar International master tech certification and have an office full of diagnostic manuals direct from IH including the posted diagrams above. So unless IH decided to wire the powerstroke *** backwards from the DT444E, its a ground activation system.

Any yes that ground provided is the same ground as every other PCM supplied ground.

 

I think I need to clarify my "ground signal" so we don't have anymore disagreements.

When I said "ground signal", I meant that it switched the ground thru the pcm. Kinda like flipping a switch so to say.

I hope that makes sense.

 

first off i have to say you guys are great. this is my first post... or question. i have a 97 F350 7.3 and i am having glow plug issues. i tested my plugs and then noticed that my gpr was not pushing the 12v though. 8 some volts (closest to the firewall) but i was getting 12 some closest to the radiator. then i read to disconnect and test. (Duh...) what was i thinkin... so then i get my 8v and nothing on the other. just now starting to track from there and i hope that someone can offer some direction. thanks

Jerry

 

Update...kinda late. I had to remove the turbo and a bunch of other things to replace the injector cups. While I had everything apart, I check continuity on the glow plug wire to the harness. Where the plug is just over the valve cover, there was continuity there. Past that, I just gave the wire a little tug. Guess what! It was loose. I then just split the wire loom and reattached the corroded wire. It now works as it should.

I had another one, same thing. Just in a different place.

Typically when you see reduced voltage, it may have something to do with corrosion somewhere. Even in the middle of the wire loom.

I just wanted to post the fix as I see a lot of people ask for help...fix the problem...and never post back what fixed it because...well...they got their fix and forget everything else. Forum only is helpful when a solution is found...and posted.